The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Julie Overbaugh - One of the best experts on this subject based on the ideXlab platform.
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Disruption of Thiamine Uptake and Growth of Cells by Feline Leukemia Virus Subgroup A
Journal of Virology, 2012Co-Authors: Ramón Mendoza, A D Miller, Julie OverbaughAbstract:ABSTRACT Feline Leukemia Virus (FeLV) is still a major cause of morbidity and mortality in domestic cats and some wild cats despite the availability of relatively effective vaccines against the Virus. FeLV subgroup A (FeLV-A) is transmitted in natural infections, and FeLV subgroups B, C, and T can evolve directly from FeLV-A by mutation and/or recombination with endogenous retroViruses in domestic cats, resulting in a variety of pathogenic outcomes. The cell surface entry receptor for FeLV-A is a putative thiamine transporter (THTR1). Here, we have addressed whether FeLV-A infection might disrupt thiamine uptake into cells and, because thiamine is an essential nutrient, whether this disruption might have pathological consequences. First, we cloned the cat ortholog of the other of the two known thiamine transporters in mammals, THTR2, and we show that Feline THTR1 (feTHTR1) and feTHTR2 both mediate thiamine uptake, but feTHTR2 does not function as a receptor for FeLV-A. We found that feTHTR1 is widely expressed in cat tissues and in cell lines, while expression of feTHTR2 is restricted. Thiamine uptake mediated by feTHTR1 was indeed blocked by FeLV-A infection, and in Feline fibroblasts that naturally express feTHTR1 and not feTHTR2, this blockade resulted in a growth arrest at physiological concentrations of extracellular thiamine. The growth arrest was reversed at high extracellular concentrations of thiamine. Our results show that FeLV-A infection can indeed disrupt thiamine uptake with pathological consequences. A prediction of these experiments is that raising the plasma levels of thiamine in FeLV-infected cats may ameliorate the pathogenic effects of infection.
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Feline Leukemia Virus t entry is dependent on both expression levels and specific interactions between cofactor and receptor
Virology, 2007Co-Authors: Heather H Cheng, Maria M Anderson, Julie OverbaughAbstract:Feline Leukemia Virus (FeLV) subgroup T uses both a multiple membrane-spanning receptor, FePit1, and a soluble cofactor, FeLIX, to enter Feline cells. FeLIX is expressed from endogenous FeLV-related sequence and resembles the receptor binding domain (RBD) of the viral envelope protein. It remains unclear whether FeLV-T receptor activity requires specific residues within FePit1 and FeLIX and/or a threshold level of receptor/cofactor expression. To address this, we examined FeLV-T infection of cells expressing variable levels of FePit1 and other gammaretroviral receptors in the presence of variable amounts of soluble cofactor, either RBD or the envelope surface subunit (SU). Cofactor-receptor pairs fall into three groups with regard to mediating FeLV-T infection: those that are efficient at all concentrations tested, such as FePit1 and FeLIX; those requiring high expression of both cofactor and receptor; and those that are non-functional as receptors even at high expression. This suggests that both expression levels and specific interactions with receptor and cofactor are critical for mediating entry of FeLV-T.
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a putative thiamine transport protein is a receptor for Feline Leukemia Virus subgroup a
Journal of Virology, 2006Co-Authors: Ramón Mendoza, Maria M Anderson, Julie OverbaughAbstract:Feline Leukemia Virus (FeLV) is a horizontally transmitted Virus that causes a variety of proliferative and immunosuppressive diseases in cats. There are four subgroups of FeLV, A, B, C, and T, each of which has a distinct receptor requirement. The receptors for all but the FeLV-A subgroup have been defined previously. Here, we report the identification of the cellular receptor for FeLV-A, which is the most transmissible form of FeLV. The receptor cDNA was isolated using a gene transfer approach, which involved introducing sequences from a Feline cell line permissive to FeLV-A into a murine cell line that was not permissive. The Feline cDNA identified by this method was approximately 3.5 kb, and included an open reading frame predicted to encode a protein of 490 amino acids. This Feline cDNA conferred susceptibility to FeLV-A when reintroduced into nonpermissive cells, but it did not render these cells permissive to any other FeLV subgroup. Moreover, these cells specifically bound FeLV-A-pseudotyped Virus particles, indicating that the cDNA encodes a binding receptor for FeLV-A. The Feline cDNA shares ∼93% amino acid sequence identity with the human thiamine transport protein 1 (THTR1). The human THTR1 receptor was also functional as a receptor for FeLV-A, albeit with reduced efficiency compared to the Feline orthologue. On the basis of these data, which strongly suggest the Feline protein is the orthologue of human THTR1, we have named the Feline receptor feTHTR1. Identification of this receptor will allow more detailed studies of the early events in FeLV transmission and may provide insights into FeLV pathogenesis.
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identification of a cellular cofactor required for infection by Feline Leukemia Virus
Science, 2000Co-Authors: Maria M Anderson, Adam S Lauring, Cara C Burns, Julie OverbaughAbstract:Retroviral infection involves continued genetic variation, leading to phenotypic and immunological selection for more fit Virus variants in the host. For retroViruses that cause immunodeficiency, pathogenesis is linked to the emergence of T cell-tropic, cytopathic Viruses. Here we show that an immunodeficiency-inducing, T cell-tropic Feline Leukemia Virus (FeLV) has evolved such that it cannot infect cells unless both a classic multiple membrane-spanning receptor molecule (Pit1) and a second coreceptor or entry factor are present. This second receptor component, which we call FeLIX, was identified as an endogenously expressed protein that is similar to a portion of the FeLV envelope protein. This cellular protein can function either as a transmembrane protein or as a soluble component to facilitate infection.
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lymphokines modulate the growth and survival of thymic tumor cells containing a novel Feline Leukemia Virus notch2 variant
Veterinary Immunology and Immunopathology, 1999Co-Authors: Michael L Linenberger, J Rohn, Ta Deng, Stephanie Ellissmith, Richard Ingber, Julie OverbaughAbstract:Tumorigenesis occurs through a multistep process initiated by genetic lesions and facilitated by endogenous and external growth/survival signals. In many malignancies, specific oncogenic mutations correlate with phenotypic characteristics, inferring lineage-specific pathogenic mechanisms. To characterize these relationships in a unique Feline tumor, we studied primary cells and two-cell lines independently-derived from a thymic lymphoma that contained and actively expressed a novel Feline Leukemia Virus (FeLV) recombinant with transduced host Notch2 sequences. All three tumor cell populations contained similar FeLV/Notch2 proviral variants and phenotypically resembled mature thymocytes. Multiple Notch2 transcripts were expressed in the cell lines, including species that correspond to viral genomes and spliced subgenomic viral mRNA. Tumor cell line FeLV/Notch2 Virus was packaged into virions; however, the variant was not efficiently transmitted to Feline cells in vitro. Primary tumor cells constitutively expressed mRNA for interleukin-4 (IL-4), IL-6 and the p40 subunit of IL-12. Lymphokine mRNA was not detected in established tumor cell lines nor was T-cell growth-promoting activity found in culture supernatants. Exogenous IL-4 enhanced primary tumor cell survival, but inhibited proliferation of the cell lines. Interleukin-4 abrogated hydrocortisone-induced apoptosis in all three populations and had divergent effects on cell line clonogenic colony formation. Exogenous IL-7 and, to a lesser degree, IL-6 also had variable positive effects on the growth and viability of the tumor cell populations. Collectively, these data suggest that thymocytes are susceptible to the transforming potential of dysregulated Notch2 and that thymopoietic factors could, through overlapping and distinct mechanisms, promote the survival and outgrowth of FeLV/Notch2-containing neoplastic cells.
Kazuo Nishigaki - One of the best experts on this subject based on the ideXlab platform.
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reduced folate carrier an entry receptor for a novel Feline Leukemia Virus variant
Journal of Virology, 2019Co-Authors: Ariko Miyake, Isaac Makundi, Junna Kawasaki, Ha Ngo, Yutaro Muto, Arshad H Khan, Desmond J Smith, Kazuo NishigakiAbstract:Feline Leukemia Virus (FeLV) is horizontally transmitted among cats and causes a variety of hematopoietic disorders. Five subgroups of FeLV, A to D and T, each with distinct receptor usages, have been described. Recently, we identified a new FeLV Env (TG35-2) gene from a pseudotyped Virus that does not belong to any known subgroup. FeLV-A is the primary Virus from which other subgroups have emerged via mutation or recombination of the subgroup A env gene. RetroVirus entry into cells is mediated by the interaction of envelope protein (Env) with specific cell surface receptors. Here, phenotypic screening of a human/hamster radiation hybrid panel identified SLC19A1, a Feline reduced folate carrier (RFC) and potential receptor for TG35-2-phenotypic Virus. RFC is a multipass transmembrane protein. Feline and human RFC cDNAs conferred susceptibility to TG35-2-pseudotyped Virus when introduced into nonpermissive cells but did not render these cells permissive to other FeLV subgroups or Feline endogenous retroVirus. Moreover, human cells with genomic deletion of RFC were nonpermissive for TG35-2-pseudotyped Virus infection, but the introduction of Feline and human cDNAs rendered them permissive. Mutation analysis of FeLV Env demonstrated that amino acid substitutions within variable region A altered the specificity of the Env-receptor interaction. We isolated and reconstructed the full-length infectious TG35-2-phenotypic proVirus from a naturally FeLV-infected cat, from which the FeLV Env (TG35-2) gene was previously isolated, and compared the replication of the Virus in hematopoietic cell lines with that of FeLV-A 61E by measuring the viral RNA copy numbers. These results provide a tool for further investigation of FeLV infectious disease.IMPORTANCE Feline Leukemia Virus (FeLV) is a member of the genus GammaretroVirus, which causes malignant diseases in cats. The most prevalent FeLV among cats is FeLV subgroup A (FeLV-A), and specific binding of FeLV-A Env to its viral receptor, thiamine transporter feTHTR1, is the first step of infection. In infected cats, novel variants of FeLV with altered receptor specificity for viral entry have emerged by mutation or recombination of the env gene. A novel FeLV variant arose from a subtle mutation of FeLV-A Env, which altered the specific interaction of the Virus with its receptor. RFC, a folate transporter, is a potential receptor for the novel FeLV variant. The perturbation of specific retroVirus-receptor interactions under selective pressure by the host results in the emergence of novel Viruses.
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Novel Feline Leukemia Virus Interference Group Based on the env Gene.
Journal of virology, 2016Co-Authors: Ariko Miyake, Minh Ha Ngo, Shinya Watanabe, Takahiro Hiratsuka, Jumpei Ito, Isaac Makundi, Junna Kawasaki, Yasuyuki Endo, Hajime Tsujimoto, Kazuo NishigakiAbstract:Feline Leukemia Virus (FeLV) subgroups have emerged in infected cats via the mutation or recombination of the env gene of subgroup A FeLV (FeLV-A), the primary Virus. We report the isolation and characterization of a novel env gene, TG35-2, and report that the TG35-2 pseudotype can be categorized as a novel FeLV subgroup. The TG35-2 envelope protein displays strong sequence identity to FeLV-A Env, suggesting that selection pressure in cats causes novel FeLV subgroups to emerge.
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genetic diversity in the Feline Leukemia Virus gag gene
Virus Research, 2015Co-Authors: Maki Kawamura, Shinya Watanabe, Yasuyuki Endo, Hajime Tsujimoto, Yuka Odahara, So Nakagawa, Kazuo NishigakiAbstract:Feline Leukemia Virus (FeLV) belongs to the GammaretroVirus genus and is horizontally transmitted among cats. FeLV is known to undergo recombination with endogenous retroViruses already present in the host during FeLV-subgroup A infection. Such recombinant FeLVs, designated FeLV-subgroup B or FeLV-subgroup D, can be generated by transduced endogenous retroviral env sequences encoding the viral envelope. These recombinant Viruses have biologically distinct properties and may mediate different disease outcomes. The generation of such recombinant Viruses resulted in structural diversity of the FeLV particle and genetic diversity of the Virus itself. FeLV env diversity through mutation and recombination has been studied, while gag diversity and its possible effects are less well understood. In this study, we investigated recombination events in the gag genes of FeLVs isolated from naturally infected cats and reference isolates. Recombination and phylogenetic analyses indicated that the gag genes often contain endogenous FeLV sequences and were occasionally replaced by entire endogenous FeLV gag genes. Phylogenetic reconstructions of FeLV gag sequences allowed for classification into three distinct clusters, similar to those previously established for the env gene. Analysis of the recombination junctions in FeLV gag indicated that these variants have similar recombination patterns within the same genotypes, indicating that the recombinant Viruses were horizontally transmitted among cats. It remains to be investigated whether the recombinant sequences affect the molecular mechanism of FeLV transmission. These findings extend our understanding of gammaretroVirus evolutionary patterns in the field.
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Notch2 transduction by Feline Leukemia Virus in a naturally infected cat.
The Journal of veterinary medical science, 2013Co-Authors: Shinya Watanabe, Masaharu Hisasue, Takahiro Hiratsuka, Jumpei Ito, Hajime Tsujimoto, Takuya Baba, Kyohei Kuse, Haruyo Ochi, Yukari Anai, Kazuo NishigakiAbstract:Feline Leukemia Virus (FeLV) induces neoplastic and nonneoplastic diseases in cats. The transduction of cellular genes by FeLV is sometimes observed and associated with neoplastic diseases including lymphoma and sarcoma. Here, we report the first natural case of Feline Notch2 transduction by FeLV in an infected cat with multicentric lymphoma and hypercalcemia. We cloned recombinant FeLVs harboring Notch2 in the env gene. Notch2 was able to activate expression of a reporter gene, similar to what was previously reported in cats with experimental FeLV-induced thymic lymphoma. Our findings suggest that the transduction of Notch2 strongly correlates with FeLV-induced lymphoma.
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phylogenetic and structural diversity in the Feline Leukemia Virus env gene
PLOS ONE, 2013Co-Authors: Shinya Watanabe, Yasuyuki Endo, Hajime Tsujimoto, Haruyo Ochi, Yukari Anai, Maki Kawamura, Yuka Odahara, So Nakagawa, Kazuo NishigakiAbstract:Feline Leukemia Virus (FeLV) belongs to the genus GammaretroVirus, and causes a variety of neoplastic and non-neoplastic diseases in cats. Alteration of viral env sequences is thought to be associated with disease specificity, but the way in which genetic diversity of FeLV contributes to the generation of such variants in nature is poorly understood. We isolated FeLV env genes from naturally infected cats in Japan and analyzed the evolutionary dynamics of these genes. Phylogenetic reconstructions separated our FeLV samples into three distinct genetic clusters, termed Genotypes I, II, and III. Genotype I is a major genetic cluster and can be further classified into Clades 1–7 in Japan. Genotypes were correlated with geographical distribution; Genotypes I and II were distributed within Japan, whilst FeLV samples from outside Japan belonged to Genotype III. These results may be due to geographical isolation of FeLVs in Japan. The observed structural diversity of the FeLV env gene appears to be caused primarily by mutation, deletion, insertion and recombination, and these variants may be generated de novo in individual cats. FeLV interference assay revealed that FeLV genotypes did not correlate with known FeLV receptor subgroups. We have identified the genotypes which we consider to be reliable for evaluating phylogenetic relationships of FeLV, which embrace the high structural diversity observed in our sample. Overall, these findings extend our understanding of GammaretroVirus evolutionary patterns in the field, and may provide a useful basis for assessing the emergence of novel strains and understanding the molecular mechanisms of FeLV transmission in cats.
Hajime Tsujimoto - One of the best experts on this subject based on the ideXlab platform.
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Novel Feline Leukemia Virus Interference Group Based on the env Gene.
Journal of virology, 2016Co-Authors: Ariko Miyake, Minh Ha Ngo, Shinya Watanabe, Takahiro Hiratsuka, Jumpei Ito, Isaac Makundi, Junna Kawasaki, Yasuyuki Endo, Hajime Tsujimoto, Kazuo NishigakiAbstract:Feline Leukemia Virus (FeLV) subgroups have emerged in infected cats via the mutation or recombination of the env gene of subgroup A FeLV (FeLV-A), the primary Virus. We report the isolation and characterization of a novel env gene, TG35-2, and report that the TG35-2 pseudotype can be categorized as a novel FeLV subgroup. The TG35-2 envelope protein displays strong sequence identity to FeLV-A Env, suggesting that selection pressure in cats causes novel FeLV subgroups to emerge.
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genetic diversity in the Feline Leukemia Virus gag gene
Virus Research, 2015Co-Authors: Maki Kawamura, Shinya Watanabe, Yasuyuki Endo, Hajime Tsujimoto, Yuka Odahara, So Nakagawa, Kazuo NishigakiAbstract:Feline Leukemia Virus (FeLV) belongs to the GammaretroVirus genus and is horizontally transmitted among cats. FeLV is known to undergo recombination with endogenous retroViruses already present in the host during FeLV-subgroup A infection. Such recombinant FeLVs, designated FeLV-subgroup B or FeLV-subgroup D, can be generated by transduced endogenous retroviral env sequences encoding the viral envelope. These recombinant Viruses have biologically distinct properties and may mediate different disease outcomes. The generation of such recombinant Viruses resulted in structural diversity of the FeLV particle and genetic diversity of the Virus itself. FeLV env diversity through mutation and recombination has been studied, while gag diversity and its possible effects are less well understood. In this study, we investigated recombination events in the gag genes of FeLVs isolated from naturally infected cats and reference isolates. Recombination and phylogenetic analyses indicated that the gag genes often contain endogenous FeLV sequences and were occasionally replaced by entire endogenous FeLV gag genes. Phylogenetic reconstructions of FeLV gag sequences allowed for classification into three distinct clusters, similar to those previously established for the env gene. Analysis of the recombination junctions in FeLV gag indicated that these variants have similar recombination patterns within the same genotypes, indicating that the recombinant Viruses were horizontally transmitted among cats. It remains to be investigated whether the recombinant sequences affect the molecular mechanism of FeLV transmission. These findings extend our understanding of gammaretroVirus evolutionary patterns in the field.
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Notch2 transduction by Feline Leukemia Virus in a naturally infected cat.
The Journal of veterinary medical science, 2013Co-Authors: Shinya Watanabe, Masaharu Hisasue, Takahiro Hiratsuka, Jumpei Ito, Hajime Tsujimoto, Takuya Baba, Kyohei Kuse, Haruyo Ochi, Yukari Anai, Kazuo NishigakiAbstract:Feline Leukemia Virus (FeLV) induces neoplastic and nonneoplastic diseases in cats. The transduction of cellular genes by FeLV is sometimes observed and associated with neoplastic diseases including lymphoma and sarcoma. Here, we report the first natural case of Feline Notch2 transduction by FeLV in an infected cat with multicentric lymphoma and hypercalcemia. We cloned recombinant FeLVs harboring Notch2 in the env gene. Notch2 was able to activate expression of a reporter gene, similar to what was previously reported in cats with experimental FeLV-induced thymic lymphoma. Our findings suggest that the transduction of Notch2 strongly correlates with FeLV-induced lymphoma.
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phylogenetic and structural diversity in the Feline Leukemia Virus env gene
PLOS ONE, 2013Co-Authors: Shinya Watanabe, Yasuyuki Endo, Hajime Tsujimoto, Haruyo Ochi, Yukari Anai, Maki Kawamura, Yuka Odahara, So Nakagawa, Kazuo NishigakiAbstract:Feline Leukemia Virus (FeLV) belongs to the genus GammaretroVirus, and causes a variety of neoplastic and non-neoplastic diseases in cats. Alteration of viral env sequences is thought to be associated with disease specificity, but the way in which genetic diversity of FeLV contributes to the generation of such variants in nature is poorly understood. We isolated FeLV env genes from naturally infected cats in Japan and analyzed the evolutionary dynamics of these genes. Phylogenetic reconstructions separated our FeLV samples into three distinct genetic clusters, termed Genotypes I, II, and III. Genotype I is a major genetic cluster and can be further classified into Clades 1–7 in Japan. Genotypes were correlated with geographical distribution; Genotypes I and II were distributed within Japan, whilst FeLV samples from outside Japan belonged to Genotype III. These results may be due to geographical isolation of FeLVs in Japan. The observed structural diversity of the FeLV env gene appears to be caused primarily by mutation, deletion, insertion and recombination, and these variants may be generated de novo in individual cats. FeLV interference assay revealed that FeLV genotypes did not correlate with known FeLV receptor subgroups. We have identified the genotypes which we consider to be reliable for evaluating phylogenetic relationships of FeLV, which embrace the high structural diversity observed in our sample. Overall, these findings extend our understanding of GammaretroVirus evolutionary patterns in the field, and may provide a useful basis for assessing the emergence of novel strains and understanding the molecular mechanisms of FeLV transmission in cats.
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identification of a novel common proviral integration site flit 1 in Feline Leukemia Virus induced thymic lymphoma
Virology, 2009Co-Authors: Yasuhito Fujino, Hajime Tsujimoto, Koichi Ohno, Kathleen A Hayes, Chunpeng Liao, Yan Shi Zhao, Judong Pan, Lawrence E Mathes, Pradip RoyburmanAbstract:A new proviral integration site for Feline Leukemia Virus (FeLV), termed flit-1, was identified from Feline thymic lymphoma. Among 35 FeLV-related tumors examined, 5 of 25 thymic lymphomas demonstrated proviral insertion within flit-1 locus whereas none of four alimentary and five multicentric lymphomas and one T-lymphoid Leukemia examined had rearrangement in this region. Extensive sequence analysis has shown that flit-1, which is noncoding, is conserved on human chromosome 12 and mouse chromosome 15. The human and murine homologs of flit-1 are positioned approximately 30-kb upstream to activin-A receptor type II-like 1 (ACVRL1/ALK1) gene. Expression of ACVRL1 mRNA was examined in two of five lymphomas with flit-1 rearrangement and detected in both of the two whereas normal thymuses and seven lymphoid tumors without flit-1 rearrangement had no detectable expression. Therefore, flit-1 appears to represent a novel FeLV proviral common integration domain that may influence lymphomagenesis as insertional mutagenesis.
Sue Vandewoude - One of the best experts on this subject based on the ideXlab platform.
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Feline Leukemia Virus felv endogenous and exogenous recombination events result in multiple felv b subtypes during natural infection
Journal of Virology, 2021Co-Authors: Katelyn Erbeck, Elliott S Chiu, Simona Kraberger, Roderick B Gagne, Melody E Roelkeparker, Sue VandewoudeAbstract:Feline Leukemia Virus (FeLV) is associated with a range of clinical signs in felid species. Differences in disease processes are closely related to genetic variation in the envelope (env) region of the genome of six defined subgroups. The primary hosts of FeLV are domestic cats of the Felis genus that also harbor endogenous FeLV (enFeLV) elements stably integrated in their genomes. EnFeLV elements display 86% nucleotide identity to exogenous, horizontally transmitted FeLV (FeLV-A). Variation between enFeLV and FeLV-A is primarily in the long terminal repeat (LTR) and env regions, which potentiates generation of the FeLV-B recombinant subgroup during natural infection. The aim of this study was to examine recombination behavior of exogenous FeLV (exFeLV) and enFeLV in a natural FeLV epizootic. We previously described that of 65 individuals in a closed colony, 32 had productive FeLV-A infection, and 22 of these individuals had detectable circulating FeLV-B. We cloned and sequenced the env gene of FeLV-B, FeLV-A, and enFeLV spanning known recombination breakpoints and examined between 1-13 clones in 22 animals with FeLV-B to assess sequence diversity and recombination breakpoints. Our analysis revealed that FeLV-A circulating in the population, as well as enFeLV env sequences, are highly conserved. We documented many recombination breakpoints resulting in the production of unique FeLV-B genotypes. More than half of the cats harbored more than one FeLV-B variant, suggesting multiple recombination events between enFeLV and FeLV-A. We concluded that FeLV-B was predominantly generated de novo within each host, though we could not definitively rule out horizontal transmission, as nearly all cats harbored FeLV-B sequences that were genetically highly similar to those identified in other individual. This work represents a comprehensive analysis of endogenous-exogenous retroviral interactions with important insights into host-viral interactions that underlie disease pathogenesis in a natural setting. Importance Feline Leukemia Virus (FeLV) is a felid retroVirus with a variety of disease outcomes. Exogenous FeLV-A is the Virus subgroup almost exclusively transmitted between cats. Recombination between FeLV-A and endogenous FeLV analogues in the cat genome may result in emergence of largely replication-defective, but highly virulent subgroups. FeLV-B is formed when the 3' envelope (env) region of endogenous FeLV (enFeLV) recombines with that of the exogenous FeLV (exFeLV) during viral reverse transcription and integration. Both domestic cats and wild relatives of the Felis genus harbor enFeLV, which has been shown to limit FeLV-A disease outcome. However, enFeLV also contributes genetic material to the recombinant FeLV-B subgroup. This study evaluates endogenous-exogenous recombination outcomes in a naturally infected closed-colony of cats to determine mechanisms and risk of endogenous retroviral recombination during exogenous Virus exposure that leads to enhanced virulence. While FeLV-A and enFeLV env regions were highly conserved from cat to cat, nearly all individuals with emergent FeLV-B had unique combinations of genotypes, representative of a wide range of recombination sites within env. The findings provide insight into unique recombination patterns for emergence of new pathogens and can be related to similar Viruses across species.
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Feline Leukemia Virus felv endogenous and exogenous recombination events result in multiple felv b subtypes during natural infection
bioRxiv, 2021Co-Authors: Katelyn Erbeck, Elliott S Chiu, Simona Kraberger, Roderick B Gagne, Melody E Roelkeparker, Sue VandewoudeAbstract:Abstract Feline Leukemia Virus (FeLV) is associated with a range of clinical signs in felid species. The primary hosts of FeLV are domestic cats of the Felis genus that also harbor endogenous FeLV (enFeLV) elements stably integrated in their genomes. EnFeLV elements display 86% nucleotide identity to exogenous, horizontally transmitted FeLV (FeLV-A). Variation between enFeLV and FeLV-A is primarily in the long terminal repeat (LTR) and env regions, which potentiates generation of FeLV-B recombinant subtypes during natural infection with enhanced virulence. The aim of this study was to examine exogenous FeLV (exFeLV) and enFeLV recombination events in a natural FeLV epizootic. We previously described that of 32 individuals in a closed colony with productive FeLV-A infection, 22 had detectable circulating FeLV-B. We cloned and sequenced the env gene of FeLV-B, FeLV-A, and enFeLV spanning known recombination breakpoints, examining between 1-13 clones per individual to assess sequence diversity and recombination sites. We documented multiple recombination breakpoints resulting in the production of unique FeLV-B genotypes. At least half of the cats harbored more than one FeLV-B variant, and almost all animals had variants similar to those recovered from at least one other individual in the colony. This analysis reveals that FeLV-B is predominantly generated de novo within each host, though horizontal transmission may be inferred based upon FeLV-B sequence identities between individuals. This work represents a comprehensive analysis of endogenous-exogenous retroviral interactions with important insights into host-viral interactions that underlie disease pathogenesis in a natural setting. Importance Feline Leukemia Virus (FeLV) is a felid retroVirus associated with a variety of disease outcomes. Exogenous FeLV-A is the most common horizontally transmitted Virus subgroup. Domestic cats (Felis catus) harbor endogenous copies of FeLV (enFeLV) in their genomes. Recombination between FeLV-A and enFeLV may result in emergence of largely replication-defective, but highly virulent recombinant strains. FeLV-B, the most common recombinant form, results when enFeLV env recombines with FeLV-A during FeLV replication. This study evaluated endogenous-exogenous recombination outcomes in a naturally-infected closed colony of domestic cats to determine recombination sites and FeLV-B genotypic heterogeneity associated with enhanced disease virulence. While FeLV-A and enFeLV genotypes were highly conserved, a large number of unique FeLV-B variants were identified in association with predicted recombination hotspots. The findings provide insight into recombination events between viral and host genomes that result in new, and potentially more pathogenic, viral strains.
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endogenous Feline Leukemia Virus sirna transcription may interfere with exogenous felv infection
bioRxiv, 2021Co-Authors: Elliott S Chiu, Sue VandewoudeAbstract:Endogenous retroViruses (ERVs) are increasingly recognized for biological impacts on host cell function and susceptibility to infectious agents, particularly in relation to interactions with exogenous retroviral progenitors (XRVs). ERVs can simultaneously promote and restrict XRV infections using different mechanisms that are Virus- and host-specific. The majority of endogenous-exogenous retroviral interactions have been evaluated in experimental mouse or chicken systems which are limited in their ability to extend findings to naturally infected outbred animals. Feline Leukemia Virus (FeLV) has a relatively well-characterized endogenous retroVirus with a coexisting virulent exogenous counterpart and is endemic worldwide in domestic cats. We have previously documented an association between endogenous FeLV LTR copy number and abrogated exogenous FeLV in naturally infected cats and experimental infections in tissue culture. Analyses described here examine limited FeLV replication in experimentally infected peripheral blood mononuclear cells. We further examine NCBI Sequence Read Archive RNA transcripts to evaluate enFeLV transcripts and RNA interference precursors. We find that lymphoid-derived tissues, which are experimentally less permissive to exogenous FeLV infection, transcribe higher levels of enFeLV under basal conditions. Transcription of enFeLV-LTR segments is significantly greater than other enFeLV genes. We documented transcription of a 21-nt miRNA just 3' to the enFeLV 5'-LTR in the Feline miRNAome of all datasets evaluated (n=27). Our findings point to important biological functions of enFeLV transcription linked to solo LTRs distributed within the domestic cat genome, with potential impacts on domestic cat exogenous FeLV susceptibility and pathogenesis. ImportanceEndogenous retroViruses (ERVs) are increasingly implicated in host cellular processes and susceptibility to infectious agents, specifically regarding interactions with exogenous retroviral progenitors (XRVs). Exogenous Feline Leukemia Virus (FeLV) and its endogenous counterpart (enFeLV) represent a well characterized, naturally occurring XRV-ERV dyad. We have previously documented an abrogated FeLV infection in both naturally infected cats and experimental fibroblast infections that harbor higher enFeLV proviral loads. Using an in silico approach, we provide evidence of miRNA-transcription that are produced in tissues most important for FeLV infection, replication, and transmission. Our findings point to important biological functions of enFeLV transcription linked to solo-LTRs distributed within the Feline genome, with potential impacts on domestic cat exogenous FeLV susceptibility and pathogenesis. This body of work provides additional evidence of RNAi as a mechanism of viral interference and is a demonstration of ERV exaptation by the host to defend against related XRVs.
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presence of endogenous viral elements negatively correlates with Feline Leukemia Virus susceptibility in puma and domestic cat cells
Journal of Virology, 2020Co-Authors: Elliott S Chiu, Sue VandewoudeAbstract:While Feline Leukemia Virus (FeLV) has been shown to infect felid species other than the endemic domestic cat host, differences in FeLV susceptibility among species has not been evaluated. Previous reports have noted a negative correlation between endogenous FeLV (enFeLV) copy number and exogenous FeLV (exFeLV) infection outcomes in domestic cats. Since felids outside the genus Felis do not harbor enFeLV genomes, we hypothesized absence of enFeLV results in more severe disease consequences in felid species lacking these genomic elements. We infected primary fibroblasts isolated from domestic cats (Felis catus) and pumas (Puma concolor) with FeLV and quantitated proviral and viral antigen loads. Domestic cat enFeLV env and long terminal repeat (LTR) copy numbers were determined for each individual and compared to FeLV viral outcomes. FeLV proviral and antigen levels were also measured in 6 naturally infected domestic cats and 11 naturally infected Florida panthers (P. concolor coryi). We demonstrated that puma fibroblasts are more permissive to FeLV than domestic cat cells, and domestic cat FeLV restriction was highly related to enFeLV-LTR copy number. Terminal tissues from FeLV-infected Florida panthers and domestic cats had similar exFeLV proviral copy numbers, but Florida panther tissues have higher FeLV antigen loads. Our work indicates that enFeLV-LTR elements negatively correlate with exogenous FeLV replication. Further, Puma concolor samples lacking enFeLV are more permissive to FeLV infection than domestic cat samples, suggesting that endogenization can play a beneficial role in mitigating exogenous retroviral infections. Conversely, presence of endogenous retroelements may relate to new host susceptibility during viral spillover events.IMPORTANCE Feline Leukemia Virus (FeLV) can infect a variety of felid species. Only the primary domestic cat host and related small cat species harbor a related endogenous Virus in their genomes. Previous studies noted a negative association between the endogenous Virus copy number and exogenous Virus infection in domestic cats. This report shows that puma cells, which lack endogenous FeLV, produce more Virus more rapidly than domestic cat fibroblasts following cell culture challenge. We document a strong association between domestic cat cell susceptibility and FeLV long terminal repeat (LTR) copy number, similar to observations in natural FeLV infections. Viral replication does not, however, correlate with FeLV env copy number, suggesting that this effect is specific to FeLV-LTR elements. This discovery indicates a protective capacity of the endogenous Virus against the exogenous form, either via direct interference or indirectly via gene regulation, and may suggest evolutionary outcomes of retroviral endogenization.
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multiple introductions of domestic cat Feline Leukemia Virus in endangered florida panthers1
Emerging Infectious Diseases, 2019Co-Authors: Elliott S Chiu, Mark W. Cunningham, Simona Kraberger, Lara Cusack, Melody E Roelke, Sue VandewoudeAbstract:The endangered Florida panther (Puma concolor coryi) had an outbreak of infection with Feline Leukemia Virus (FeLV) in the early 2000s that resulted in the deaths of 3 animals. A vaccination campaign was instituted during 2003-2007 and no additional cases were recorded until 2010. During 2010-2016, six additional FeLV cases were documented. We characterized FeLV genomes isolated from Florida panthers from both outbreaks and compared them with full-length genomes of FeLVs isolated from contemporary Florida domestic cats. Phylogenetic analyses identified at least 2 circulating FeLV strains in panthers, which represent separate introductions from domestic cats. The original FeLV Virus outbreak strain is either still circulating or another domestic cat transmission event has occurred with a closely related variant. We also report a case of a cross-species transmission event of an oncogenic FeLV recombinant (FeLV-B). Evidence of multiple FeLV strains and detection of FeLV-B indicate Florida panthers are at high risk for FeLV infection.
Hans Lutz - One of the best experts on this subject based on the ideXlab platform.
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Survey of the Feline Leukemia Virus infection status of cats in Southern Germany.
Journal of feline medicine and surgery, 2012Co-Authors: Theresa Englert, Hans Lutz, Carola Sauter-louis, Katrin HartmannAbstract:Most studies that investigate the prevalence of infections with Feline Leukemia Virus (FeLV) are based on the detection of p27 antigen in blood, but they do not detect proviral DNA to identify the ...
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Feline Leukemia Virus infection a threat for the survival of the critically endangered iberian lynx lynx pardinus
Veterinary Immunology and Immunopathology, 2010Co-Authors: Marina L. Meli, Valentino Cattori, F. Martínez, G. López, A. Vargas, Regina Hofmannlehmann, Francisco Palomares, Jose Vicente Lopezbao, Hans LutzAbstract:The Iberian lynx (Lynx pardinus) is considered the most endangered felid species in the world. To date, less than 200 animals remain in the wild. Low numbers and genetic uniformity may contribute to render this species particularly susceptible to infectious diseases. Different pathogens have been identified in Iberian lynxes; including several Feline bacterial and viral agents. Within a 6-month period starting in December 2006, 12 lynxes living in the northern part of the Donana area were found to be infected with Feline Leukemia Virus (FeLV). Eleven of these animals were antigenemic, and four of them died in the wild in less than 6 months since the first infected animal had been discovered. The remaining viremic lynxes were captured and allocated to a quarantine center to stop the spread of the infection. An additional three animals died shortly in the quarantine center due to acute anemic disease. Sequencing of the envelope surface unit gene revealed a common origin for the FeLV found in all lynxes. The sequences were closely related to FeLV-A/61E, originally isolated from cats in the USA. Our data demonstrate that, similarly to FeLV, the introduction of a new or particularly pathogenic infection brought into the small population of Iberian lynxes by other wild carnivores or feral cats and dogs roaming in the same habitats have severe consequences. It could result in epidemics that have the potential to eradicate the entire lynx population.
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role of latent Feline Leukemia Virus infection in nonregenerative cytopenias of cats
Journal of Veterinary Internal Medicine, 2010Co-Authors: Bianca Stutzer, Hans Lutz, F Muller, M Majzoub, Craig E Greene, W Hermanns, Katrin HartmannAbstract:Background: Nonregenerative cytopenias such as nonregenerative anemia, neutropenia, and thrombocytopenia in cats with Feline Leukemia Virus (FeLV) antigen are assumed to be caused by the underlying FeLV infection. In addition, cats with negative FeLV antigen-test results that have cytopenias of unknown etiology often are suspected to suffer from latent FeLV infection that is responsible for the nonregenerative cytopenias. Objective: The purpose of this study was to assess the role of latent FeLV infection by polymerase chain reaction (PCR) in bone marrow of cats with nonregenerative cytopenias that had negative FeLV antigen test results in blood. Animals: Thirty-seven cats were included in the patient group. Inclusion criteria were (1) nonregenerative cytopenia of unknown origin and (2) negative FeLV antigen test result. Antigenemia was determined by detection of free FeLV p27 antigen by ELISA in serum. Furthermore, 7 cats with positive antigen test results with nonregenerative cytopenia were included as control group I, and 30 cats with negative antigen test results without nonregenerative cytopenia were included as control group II. Methods: Whole blood and bone marrow samples were tested by 2 different PCR assays detecting sequences of the envelope or long terminal repeat genes. FeLV immunohistochemistry was performed in bone marrow samples. Results: Two of the 37 cats (5.4%) in the patient group were positive on the bone marrow PCR results and thus were latently infected with FeLV. Conclusions and Clinical Importance: The findings of this study suggest that FeLV latency is rare in cats with nonregenerative cytopenias.
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fecal shedding of infectious Feline Leukemia Virus and its nucleic acids a transmission potential
Veterinary Microbiology, 2009Co-Authors: M A Gomeskeller, Ravi Tandon, Enikő Gonczi, B Grenacher, R Hofmanlehmann, Hans LutzAbstract:Although it is assumed that fecal shedding of Feline Leukemia Virus (FeLV) constitutes a transmission potential, no study has been performed showing that feces of infected cats can be a source of infection. In this study, we investigated fecal viral shedding of FeLV and its role in viral pathogenesis with the goal to improve infection control. FeLV RNA and DNA levels were determined in rectal swabs of experimentally infected cats by real-time PCR, and the results were correlated with proviral and viral loads in whole blood and plasma, respectively, and plasma p27 levels. All antigenemic cats shed FeLV RNA and DNA in feces. To determine whether the viral RNA detected was infectious, Virus isolation from feces was also performed. Infectious Virus was isolated from feces of antigenemic cats, and these results perfectly correlated with the isolation of Virus from plasma. Naive cats exposed to these feces seroconverted, showing that infection through feces took place, but remained negative for the presence of FeLV proVirus and p27 in blood, an outcome so far not described. Some of the organs collected after euthanasia were proVirus positive at low copy numbers. From these results it is concluded that fecal shedding of FeLV plays a role in transmission, but it is probably of secondary importance in viral pathogenesis. Nevertheless, sharing of litter pans by susceptible and viremic cats could increase the environmental infectious pressure and appropriate measures should be taken to avoid unnecessary viral exposure.
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real time pcr investigation of Feline Leukemia Virus proviral and viral rna loads in leukocyte subsets
Veterinary Immunology and Immunopathology, 2008Co-Authors: Valentino Cattori, Barbara Riond, Hans Lutz, Ravi Tandon, Andrea C. Pepin, Marina L. Meli, Barbara Willi, Regina HofmannlehmannAbstract:Cats exposed to Feline Leukemia Virus (FeLV), a naturally occurring gammaretroVirus develop either progressive or regressive infection. Recent studies using analyses with enhanced sensitivity have correlated loads throughout FeLV with the clinical outcome, though remarkably, during the acute phase of infection, proviral and viral RNA burdens in the peripheral blood do not differ between groups. We hypothesized that viral loads in specific leukocyte subsets influence the infection outcome. Using a method established to determine the proviral and cell-associated viral RNA loads in specific leukocyte subsets, we evaluated viral loads in eleven FeLV-exposed specific pathogen-free (SPF) cats 2.5 years post-infection. Six cats had undergone regressive infection whereas five were persistently viremic. Aviremic cats had lower total proviral blood loads than the persistently infected cats and FeLV proviral DNA was shown to be integrated into genomic DNA in four out of four animals. Lymphocytes were predominantly infected vs. moncytes and granulocytes in aviremic cats. In contrast, persistently viremic cats were proVirus-positive in all leukocyte subsets. The acute phase kinetics of FeLV infection were analyzed in two additional cats; an early lymphoreticular phase with productive infection in lymphocytes in both cats and in monocytes in one cat was followed by infection of the granulocytes; both cats became persistently infected. These results indicate that FeLV persistent viremia is associated with secondary viremia of bone marrow origin, whereas regressive cats only sustain a non-productive infection in low numbers of lymphocytes.
