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Barry J. Beaty - One of the best experts on this subject based on the ideXlab platform.
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Heterologous reassortment of bunyaviruses in Aedes triseriatus mosquitoes and transovarial and oral transmission of newly evolved genotypes
2016Co-Authors: Barry J. Beaty, Gerald D. Baldridge, David H. L. Bishop, Martinez J. HewlettAbstract:Aedes triseriatus mosquitoes were orally infected with two different California serogroup bunyaviruses (La Crosse and snowshoe hare viruses) and high frequency reassortment occurred in these mosquitoes. Increased viral replication and subsequent gene segment reassort-ment was noted in the ovaries of mosquitoes that had ingested multiple blood-meals. To determine whether newly generated reassortant viruses could be trans-mitted transovaria[ly to progeny mosquitoes, adult female mosquitoes were inoculated with the two temperature-sensitive (ts) parental viruses, and allowed to blood-feed and oviposit. Of 58 infected progeny mosquitoes assayed, six (10%) contained non-ts viruses, and three of these transmitted non-ts viruses to a susceptible host. Selected viruses of the non-ts phenotype, which were isolated from mosquitoes and from mice fed upon by the mosquitoes, were demon-strated to be reassortant viruses by oligonucleotide fingerprinting
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ral ssBioMed CentVirology Journal Open AcceResearch Potential for La Crosse virus segment reassortment in nature
2015Co-Authors: Sara M. Reese, Bradley J. Blitvich, Carol D. Blair, Barry J. Beaty, Dave Geske, William C. BlackAbstract:The evolutionary success of La Crosse virus (LACV, family Bunyaviridae) is due to its ability to adapt to changing conditions through intramolecular genetic changes and segment reassortment. Vertical transmission of LACV in mosquitoes increases the potential for segment reassortment. Studies were conducted to determine if segment reassortment was occurring in naturally infected Aedes triseriatus from Wisconsin and Minnesota in 2000, 2004, 2006 and 2007. Mosquito eggs were collected from various sites in Wisconsin and Minnesota. They were reared in the laboratory and adults were tested for LACV antigen by immunofluorescence assay. RNA was isolated from the abdomen of infected mosquitoes and portions of the small (S), medium (M) and large (L) viral genome segments were amplified by RT-PCR and sequenced. Overall, the viral sequences from 40 infected mosquitoes and 5 virus isolates were analyzed. Phylogenetic and linkage disequilibrium analyses revealed that approximately 25 % of infected mosquitoes and viruses contained reassorted genome segments, suggesting that LACV segment reassortment is frequent in nature. Background In the 1970s, La Crosse virus (LACV family Bunyaviridae
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transovarially infected mosquitoes
2015Co-Authors: Monica K. Borucki, Carol D. Blair, Beulah M. Parker, Barry J. BeatyAbstract:Rapid evolution of bunyaviruses may occur by RNA segment reassortment between closely related viruses. Reassortment between viruses occurs in dually infected mosquitoes when two different viruses are simultaneously ingested or when the second virus is ingested within 2 days of the first virus. By 3 days after oral infection, interference to superinfection occurs, thus limiting the potential for evolution. Aedes triseriatus mosquitoes can also be transovarially infected (TIM) with LaCrosse (LAC) virus. In these studies, the potential for oral superinfection of TIM mosquitoes was assessed. Approximately 20 % of mosquitoes TIM with either a temperature-sensitive LAC virus or wild-type (wt) LAC virus became superinfected by ingesting blood meals containing wt LAC or snowshoe hare (SSH) viruses. LAC virus TIM mosquitoes superinfected with SSH virus were detected by blot hybridization or RT–PCR. Viruses from these mosquitoes were plaque purified and genotyped using RT–PCR. Reassortant genomes were detected in 2–3 % of the viruses genotyped, and 4–0 % of the genomes tested were diploid for one genome segment
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SHORT REPORT: DIAPAUSE, TRANSOVARIAL TRANSMISSION, AND FILIAL INFECTION RATES IN GEOGRAPHIC STRAINS OF LA CROSSE VIRUS-INFECTED Aedes triseriatus
2013Co-Authors: Jennifer Woodring, Carol D. Blair, M M Mcgaw, Laura J Chandler, Cynthia T Oray, Barry J. BeatyAbstract:Abstract. La Crosse (LAC) virus is transmitted horizontally to vertebrates and vertically to progeny by Aedes triseriatus mosquitoes, and in northern midwestern states, this virus overwinters in diapausing eggs of the vector. In Florida, the vector remains active throughout the year and does not diapause. To determine if there is an association between diapause and vertical transmission efficiency of LAC virus, transovarial transmission (TOT), and filial infection (FI) rates were determined for geographic strains of Ae. triseriatus. The TOT rates were not significantly different for Ae. triseriatus originating from Florida (78%) and those from Wisconsin (85%). The FI rates did differ significantly between the two groups (33 % and 45%, respectively, for the Florida and Wisconsin mosquitoes). Furthermore, a line of mosquitoes was selected from a Wisconsin colony that had a reduced diapause phenotype (the AD � strain). While this strain displayed TOT rates that were the same as the other Wisconsin mosquitoes (85%), the FI rates were significantly lower (34%), indicating a reduction in TOT efficiency. The role of vertical transmission capacity in LAC virus endemicity remains to be determined. Aedes triseriatus is the principal vector of La Crosse (LAC) virus, the leading cause of pediatric arboviral encephalitis in the United States. 1 This virus is efficiently vertically transmitted in Ae. triseriatus; transovarial transmissio
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Potential for La Crosse virus segment reassortment in nature.
Virology journal, 2008Co-Authors: Sara M. Reese, Bradley J. Blitvich, Carol D. Blair, Barry J. Beaty, Dave Geske, William C. BlackAbstract:The evolutionary success of La Crosse virus (LACV, family Bunyaviridae) is due to its ability to adapt to changing conditions through intramolecular genetic changes and segment reassortment. Vertical transmission of LACV in mosquitoes increases the potential for segment reassortment. Studies were conducted to determine if segment reassortment was occurring in naturally infected Aedes triseriatus from Wisconsin and Minnesota in 2000, 2004, 2006 and 2007. Mosquito eggs were collected from various sites in Wisconsin and Minnesota. They were reared in the laboratory and adults were tested for LACV antigen by immunofluorescence assay. RNA was isolated from the abdomen of infected mosquitoes and portions of the small (S), medium (M) and large (L) viral genome segments were amplified by RT-PCR and sequenced. Overall, the viral sequences from 40 infected mosquitoes and 5 virus isolates were analyzed. Phylogenetic and linkage disequilibrium analyses revealed that approximately 25% of infected mosquitoes and viruses contained reassorted genome segments, suggesting that LACV segment reassortment is frequent in nature.
Edward D. Walker - One of the best experts on this subject based on the ideXlab platform.
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genome sequence of flavobacteriaceae strain w22 isolated from a tree hole mosquito habitat
Microbiology resource announcements, 2020Co-Authors: Shicheng Chen, Edward D. WalkerAbstract:ABSTRACT The bacterium Flavobacteriaceae strain W22 was isolated from the water column of a tree hole larval habitat of the mosquito Aedes triseriatus. The draft genome contained 3,796,379 bp, a G+C content of 35.4%, and several genes encoding enzymes functioning in polysaccharide degradation, gliding motility, and the type IX protein secretion system (T9SS).
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toxicity of sulfide and ammonium to Aedes triseriatus larvae diptera culicidae in water filled tree holes and tires
Journal of Medical Entomology, 2016Co-Authors: Edward D. WalkerAbstract:Ammonium and sulfide in water of tree hole and tire habitats of Aedes triseriatus Say larvae could accumulate to toxic levels, limiting growth and production of larvae and adults. Both ions were detected in water samples taken in longitudinal series over 11 dates from 10 habitats of each type during the larval growth season, at concentrations suggestive of reducing conditions in these habitats. Ammonium was more concentrated overall in water of both habitat types, while sulfide was more concentrated in tires than in tree holes. Water of tree holes was more acidic, whereas water in tires tended to be more basic, an important difference relative to the tendency of ammonium to form the more toxic ammonia moiety under basic conditions. Oxygen saturation was low in both habitat types, indicative of hypoxic conditions such that aerobic respiration would be limited. First-and fourth-instar larvae were sensitive to ammonium and sulfide in acute dose-response assays, but LC50 values were above maximum concentrations observed under field conditions, suggesting that toxic effects of ammonium and sulfide on larvae are not acute, but could be chronic.
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elizabethkingia anophelis molecular manipulation and interactions with mosquito hosts
Applied and Environmental Microbiology, 2015Co-Authors: Shicheng Chen, Michael Bagdasarian, Edward D. WalkerAbstract:Flavobacteria (members of the family Flavobacteriaceae) dominate the bacterial community in the Anopheles mosquito midgut. One such commensal, Elizabethkingia anophelis, is closely associated with Anopheles mosquitoes through transstadial persistence (i.e., from one life stage to the next); these and other properties favor its development for paratransgenic applications in control of malaria parasite transmission. However, the physiological requirements of E. anophelis have not been investigated, nor has its capacity to perpetuate despite digestion pressure in the gut been quantified. To this end, we first developed techniques for genetic manipulation of E. anophelis, including selectable markers, reporter systems (green fluorescent protein [GFP] and NanoLuc), and transposons that function in E. anophelis. A flavobacterial expression system based on the promoter PompA was integrated into the E. anophelis chromosome and showed strong promoter activity to drive GFP and NanoLuc reporter production. Introduced, GFP-tagged E. anophelis associated with mosquitoes at successive developmental stages and propagated in Anopheles gambiae and Anopheles stephensi but not in Aedes triseriatus mosquitoes. Feeding NanoLuc-tagged cells to A. gambiae and A. stephensi in the larval stage led to infection rates of 71% and 82%, respectively. In contrast, a very low infection rate (3%) was detected in Aedes triseriatus mosquitoes under the same conditions. Of the initial E. anophelis cells provided to larvae, 23%, 71%, and 85% were digested in A. stephensi, A. gambiae, and Aedes triseriatus, respectively, demonstrating that E. anophelis adapted to various mosquito midgut environments differently. Bacterial cell growth increased up to 3-fold when arginine was supplemented in the defined medium. Furthermore, the number of NanoLuc-tagged cells in A. stephensi significantly increased when arginine was added to a sugar diet, showing it to be an important amino acid for E. anophelis. Animal erythrocytes promoted E. anophelis growth in vivo and in vitro, indicating that this bacterium could obtain nutrients by participating in erythrocyte lysis in the mosquito midgut.
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Beetle (Coleoptera: Scirtidae) Facilitation of Larval Mosquito Growth in Tree Hole Habitats is Linked to Multitrophic Microbial Interactions
Microbial Ecology, 2011Co-Authors: Kirsten Pelz-stelinski, Michael G. Kaufman, Edward D. WalkerAbstract:Container-breeding mosquitoes, such as Aedes triseriatus, ingest biofilms and filter water column microorganisms directly to obtain the bulk of their nutrition. Scirtid beetles often co-occur with A. triseriatus and may facilitate the production of mosquito adults under low-resource conditions. Using molecular genetic techniques and quantitative assays, we observed changes in the dynamics and composition of bacterial and fungal communities present on leaf detritus and in the water column when scirtid beetles co-occur with A. triseriatus. Data from terminal restriction fragment polymorphism analysis indicated scirtid presence alters the structure of fungal communities in the water column but not leaf-associated fungal communities. Similar changes in leaf and water bacterial communities occurred in response to mosquito presence. In addition, we observed increased processing of leaf detritus, higher leaf-associated enzyme activity, higher bacterial productivity, and higher leaf-associated fungal biomass when scirtid beetles were present. Such shifts suggest beetle feeding facilitates mosquito production indirectly through the microbial community rather than directly through an increase in available fine particulate organic matter.
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an acute trophic cascade among microorganisms in the tree hole ecosystem following removal of omnivorous mosquito larvae
Community Ecology, 2010Co-Authors: Edward D. Walker, Michael G. Kaufman, Richard W MerrittAbstract:Results of two field experiments showed that selective removal of omnivorous mosquito larvae (Aedes triseriatus (Say)) functioning as top predators in the food web of a temperate, tree hole ecosystem resulted rapidly in increased abundance of flagellate and then ciliate populations. Flagellate density increased from 103 per ml within 4 days of omnivore removal, followed shortly thereafter by an increase in ciliate density from 102 per ml, after which flagellate density declined, and flagellate and ciliate densities stabilized. Rod-shaped bacteria increased slightly in density after removal of larval mosquitoes, then declined as protist density increased. Cocciform bacteria did not vary in density with these changes, thus the trophic cascade dampened at the remotest trophic level. Concomitant with the increase in protist densities, some bacteria formed elongated filaments >10 μm in length, likely an anti-predation, morphological response stimulated by suddenly intensified grazing as protozoan density rose. Results suggest that feeding by omnivorous mosquito larvae exhibited strong top-down effects on flagellate and ciliate populations, depressing them to below their equilibrium densities and nearly to extinction in tree hole ecosystems.
Steven A Juliano - One of the best experts on this subject based on the ideXlab platform.
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the demographic and life history costs of fear trait mediated effects of threat of predation on Aedes triseriatus
Ecology and Evolution, 2019Co-Authors: Geoffrey D Ower, Steven A JulianoAbstract:: Predators alter prey populations via direct lethality (density-mediated effects), but in many taxa, the indirect nonlethal threat of predation may be almost as strong an effect, altering phenotypically plastic traits such as prey morphology, behavior, and life history (trait-mediated effects). There are costs to antipredator defenses and the strength of prey responses to cues of predation likely depends on both the perceived level of risk and food availability.The goal of this study was to test the hypothesis that the costs of nonlethal trait-mediated interactions impacting larvae can have carryover effects that alter life-history traits, adult characteristics, and ultimately population dynamics.The effects of Toxorhynchites rutilus kairomones and chemical alarm cues on Aedes triseriatus were assessed in a two-level factorial design manipulating nutrient level (low or high) and chemical cues of predation (present or absent).Nonlethal chemical cues of predation significantly decreased female survivorship and significantly decreased female size. Females emerged as adults significantly earlier when exposed to predation cues when there was high nutrient availability. When raised in the low nutrient treatment and exposed to predator cues, adult females had 2.1 times the hazard of death compared to high nutrient-no predator cues. Females raised in the high nutrient and predator cue treatment blood fed sooner than did females from other combinations.Fear of predation can substantially alter prey life-history traits and behavior, which can cascade into dramatic population, community, and ecosystem effects. Exposure to predator cues significantly decreased the estimated cohort rate of increase, potentially altering the expected population density of the next generation.
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a multifaceted trophic cascade in a detritus based system density trait or processing chain mediated effects
Ecosphere, 2015Co-Authors: Daniel Albenysimoes, Evaldo F Vilela, Ebony G Murrell, Steven A JulianoAbstract:We investigated three pathways by which predators on an intermediate trophic level may produce a trophic cascade in detritus-based systems. Predators may increase lower trophic levels (bacteria) by reducing density of bacteriovores, by altering behavior of bacteriovores, and by processing living bacteriovores into carcasses, feces, and dissolved nutrients that are substrates for bacteria. We tested these pathways in laboratory experiments with mosquitoes in water-filled containers. Larval Toxorhynchites rutilus prey on larval Aedes triseriatus, which feed on bacteria. Using containers stocked with oak leaf infusion as a bacterial substrate, we compared bacterial productivity at 7 and 14 days for: prey alone; prey with a predator; and prey with predation cues but no predator. Controls contained no larvae, either with predation cues or without cues. Predation cues in the control treatment increased bacterial abundance at 7 days, but this effect waned by 14 days. Aedes triseriatus larvae reduced bacterial abundance significantly at 14 days. Predator cues and real predation both eliminated the negative effect of A. triseriatus on bacterial abundance. Predation cues reduced survivorship of A. triseriatus larvae at 14 days, however this effect was smaller than the effect of real predation. We further tested effects of residues from predation as cues or as detritus in a second experiment in which A. triseriatus were killed at similar rates by: real predators; mechanical damage without the predator and carcasses left as detritus; or mechanical damage and carcasses removed. No prey larvae were killed in controls. Bacterial productivity was greater with real predation than in all other treatments and greater when prey larvae were killed or killed and removed, than in controls. Thus we find evidence that all three pathways contribute to the trophic cascade from T. rutilus to bacteria in tree hole systems.
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Predation and the evolution of prey behavior: an experiment with tree hole mosquitoes
2015Co-Authors: Steven A Juliano, Marc E. GravelAbstract:We tested for facultative changes in behavior of an aquatic insect in response to cues from predation and for evolution of prey behavior in response to experimental predation regimes. Larvae of the tree hole mosquito Aedes triseriatus reduced filtering, browsing, and time below the surface in response to water that had held a feeding larva of the predator Toxorhynchites rutilus. We subjected experimental A. triseriatus populations to culling of 50 % of the larval population, either by T. rutilus predation or by random removal. After two generations of laboratory culling, behavior of the two treatment groups diverged. Aedes triseriatus in control-culled lines retained their facultative shift from filtering to resting, but tended to lose the response of reduced browsing below the surface in water that had held a feeding predator. Predator-culled lines lost their facultative response of reduced filtering in water that had held a feeding predator and evolved toward more time resting and less time filtering in both water that had held a feeding predator and water that had held only A. triseriatus. Predator-culled lines retained their facultative response of reduced browsing below the surface in water that had held a feeding predator. Two field populations and their reciprocal hybrids responded similarly to cues from predation and did not differ in their evolutionary response to experimental culling. We conclude that consistent presence or absence of predation can select rapidly for divergence in prey behavior, including facultative behavioral responses to predators. Key words: activity, Aedes triseriatus, behavioral responses, constitutive behavior, facultative antipredator behavior, feeding behavior, predation, predator avoidance behavior, Toxorhynchites rutilus. [Behav Ecol 13:301–311 (2002)
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effects of developmental asynchrony between Aedes triseriatus diptera culicidae and its predator toxorhynchites rutilus diptera culicidae
Journal of Medical Entomology, 1997Co-Authors: Michael A Nannini, Steven A JulianoAbstract:Newly hatched Toxorhynchites rutilus (Coquillet) were added to experimental populations of Aedes triseriatus (Say) at varying days after prey hatch to test the hypothesis that a developmental asynchrony of Ae. triseriatus and Tx. rutilus leads to escape from predation by Ae. triseriatus in small water bodies. Presence of Tx. rutilus significantly affected prey survivorship. Regression of survivorship [log10 (x + 1) transformed] versus days head start for prey yielded a small, but significant positive slope, indicating that survivorship increased slightly with an increasing number of days head start. For females, mean weight at emergence was not significantly affected by treatments; however, median days to emergence differed significantly between the treatments, with females taking significantly longer to emerge with Tx. rutilus absent than when the predator was present. For males, neither mean mass nor median days to emergence was significantly affected by treatments. Treatments had no significant effect on the frequency of deaths or on mean weight of Tx. rutilus. Thus, a developmental asynchrony between Tx. rutilus and Ae. triseriatus appears to have no effects on the predator, but does have a weak effect on prey performance at high hatch densities.
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the relationship between vulnerability to predation and behavior of larval treehole mosquitoes geographic and ontogenetic differences
Oikos, 1992Co-Authors: Steven A Juliano, Lauren RemingerAbstract:We tested predictions of the hypothesis that behavioral differences are the proximate cause of interpopulation differences in vulnerability to predation in Aedes triseriatus. The predictions were : 1) A. triseriatus from sites where the predator Toxorhynchites rutilus is abundant vs rare differ in types of activities and positions occupied, or the degree to which they change behavior in the presence of T. rutilus; 2) Some activities or positions entail greater risks of predation than others; 3) High-risk behaviors are more common among larvae from sites where T. rutilus is rare vs sites where T. rutilus is common. Behavior was quantified by direct observation of individual larvae with T. rutilus present or absent. Riskiness of behaviors was quantified by recording the frequency with which different behaviors led to capture
Carol D. Blair - One of the best experts on this subject based on the ideXlab platform.
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ral ssBioMed CentVirology Journal Open AcceResearch Potential for La Crosse virus segment reassortment in nature
2015Co-Authors: Sara M. Reese, Bradley J. Blitvich, Carol D. Blair, Barry J. Beaty, Dave Geske, William C. BlackAbstract:The evolutionary success of La Crosse virus (LACV, family Bunyaviridae) is due to its ability to adapt to changing conditions through intramolecular genetic changes and segment reassortment. Vertical transmission of LACV in mosquitoes increases the potential for segment reassortment. Studies were conducted to determine if segment reassortment was occurring in naturally infected Aedes triseriatus from Wisconsin and Minnesota in 2000, 2004, 2006 and 2007. Mosquito eggs were collected from various sites in Wisconsin and Minnesota. They were reared in the laboratory and adults were tested for LACV antigen by immunofluorescence assay. RNA was isolated from the abdomen of infected mosquitoes and portions of the small (S), medium (M) and large (L) viral genome segments were amplified by RT-PCR and sequenced. Overall, the viral sequences from 40 infected mosquitoes and 5 virus isolates were analyzed. Phylogenetic and linkage disequilibrium analyses revealed that approximately 25 % of infected mosquitoes and viruses contained reassorted genome segments, suggesting that LACV segment reassortment is frequent in nature. Background In the 1970s, La Crosse virus (LACV family Bunyaviridae
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transovarially infected mosquitoes
2015Co-Authors: Monica K. Borucki, Carol D. Blair, Beulah M. Parker, Barry J. BeatyAbstract:Rapid evolution of bunyaviruses may occur by RNA segment reassortment between closely related viruses. Reassortment between viruses occurs in dually infected mosquitoes when two different viruses are simultaneously ingested or when the second virus is ingested within 2 days of the first virus. By 3 days after oral infection, interference to superinfection occurs, thus limiting the potential for evolution. Aedes triseriatus mosquitoes can also be transovarially infected (TIM) with LaCrosse (LAC) virus. In these studies, the potential for oral superinfection of TIM mosquitoes was assessed. Approximately 20 % of mosquitoes TIM with either a temperature-sensitive LAC virus or wild-type (wt) LAC virus became superinfected by ingesting blood meals containing wt LAC or snowshoe hare (SSH) viruses. LAC virus TIM mosquitoes superinfected with SSH virus were detected by blot hybridization or RT–PCR. Viruses from these mosquitoes were plaque purified and genotyped using RT–PCR. Reassortant genomes were detected in 2–3 % of the viruses genotyped, and 4–0 % of the genomes tested were diploid for one genome segment
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SHORT REPORT: DIAPAUSE, TRANSOVARIAL TRANSMISSION, AND FILIAL INFECTION RATES IN GEOGRAPHIC STRAINS OF LA CROSSE VIRUS-INFECTED Aedes triseriatus
2013Co-Authors: Jennifer Woodring, Carol D. Blair, M M Mcgaw, Laura J Chandler, Cynthia T Oray, Barry J. BeatyAbstract:Abstract. La Crosse (LAC) virus is transmitted horizontally to vertebrates and vertically to progeny by Aedes triseriatus mosquitoes, and in northern midwestern states, this virus overwinters in diapausing eggs of the vector. In Florida, the vector remains active throughout the year and does not diapause. To determine if there is an association between diapause and vertical transmission efficiency of LAC virus, transovarial transmission (TOT), and filial infection (FI) rates were determined for geographic strains of Ae. triseriatus. The TOT rates were not significantly different for Ae. triseriatus originating from Florida (78%) and those from Wisconsin (85%). The FI rates did differ significantly between the two groups (33 % and 45%, respectively, for the Florida and Wisconsin mosquitoes). Furthermore, a line of mosquitoes was selected from a Wisconsin colony that had a reduced diapause phenotype (the AD � strain). While this strain displayed TOT rates that were the same as the other Wisconsin mosquitoes (85%), the FI rates were significantly lower (34%), indicating a reduction in TOT efficiency. The role of vertical transmission capacity in LAC virus endemicity remains to be determined. Aedes triseriatus is the principal vector of La Crosse (LAC) virus, the leading cause of pediatric arboviral encephalitis in the United States. 1 This virus is efficiently vertically transmitted in Ae. triseriatus; transovarial transmissio
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EFFECT OF LA CROSSE VIRUS INFECTION ON OVERWINTERING OF Aedes triseriatus
2013Co-Authors: M M Mcgaw, Carol D. Blair, Laura J Chandler, L P Wasieloski, J. BeatyAbstract:Abstract. The effect of La Crosse (LAC) virus infection on Aedes triseriatus overwintering success was determined. Eggs from LAC virus transovarially infected (LAC TOT�) and uninfected (LAC TOT�) Ae. triseriatus colonies were induced into diapause, held in natural conditions, and returned to the laboratory at predetermined times for assay of diapause, mortality, and filial infection rates, and to examine viral transcription and replication during diapause. Embryos from the LAC TOT � colony exhibited greater cumulative mortality (16.7%) than the LAC TOT� eggs (7.3%) throughout the overwintering periods. The increased mortality rate in LAC TOT � eggs corresponded with a decrease in filial infection rates. Eggs from the LAC TOT � colony terminated diapause more readily than the LAC TOT � colony. An RNA strand-specific reverse transcriptase–polymerase chain reaction technique was used to monitor viral transcription and replication in mosquito eggs during overwintering, and to compare viral replication in diapausing and nondiapausing embryos. Viral messenger and replicative form RNA were present in eggs in all sample periods, suggesting that some virus replication occurred during diapause. 168 La Crosse (LAC) virus is a member of the Bunyavirus genus in the family Bunyaviridae. 1 This mosquito-borne virus is an important cause of pediatric arboviral encephaliti
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Quantitative Analysis of La Crosse Virus Transcription and Replication
2013Co-Authors: Brian J Kempf, Carol D. Blair, J. BeatyAbstract:Abstract. La Crosse (LAC) virus (family Bunyaviridae, genus Orthobunyavirus) small (S) segment negative-sense RNA genome (vRNA), positive-sense full-length RNA complement (vcRNA), and subgenomic mRNA were assayed in infected cell cultures and female Aedes (Ochlerotatus) triseriatus mosquito tissues using quantitative PCR (Q-PCR). During persistent infection of C6/36 (Aedes albopictus) and MAT (Aedes triseriatus) cultured cells and cytolytic infection of BHK-21 cultured cells, LAC vRNA was the most abundant RNA species, followed by mRNA and vcRNA. RNA copy numbers per cell were quantified and vRNA correlated to virus titer in cell culture medium. The Q-PCR assay proved more sensitive than reverse transcription (RT)-PCR and immunofluorescence assays (IFA) for detecting LAC virus infection of mosquitoes. After infection of female mosquitoes orally, quantities of LAC RNA increased in ovaries for 6 days, and as ovarian biosynthetic activity quiesced, LAC RNA quantities decreased then remained detectable at a low level. After a second, noninfectious blood meal, quantities of LAC RNA in ovaries increased significantly, quantitatively confirming correlation of LAC virus RNA synthesis with vector metabolic activity. Coregulation of viral replication and mosquito ovary metabolic activity may condition efficient transovarial transmission
William C. Black - One of the best experts on this subject based on the ideXlab platform.
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ral ssBioMed CentVirology Journal Open AcceResearch Potential for La Crosse virus segment reassortment in nature
2015Co-Authors: Sara M. Reese, Bradley J. Blitvich, Carol D. Blair, Barry J. Beaty, Dave Geske, William C. BlackAbstract:The evolutionary success of La Crosse virus (LACV, family Bunyaviridae) is due to its ability to adapt to changing conditions through intramolecular genetic changes and segment reassortment. Vertical transmission of LACV in mosquitoes increases the potential for segment reassortment. Studies were conducted to determine if segment reassortment was occurring in naturally infected Aedes triseriatus from Wisconsin and Minnesota in 2000, 2004, 2006 and 2007. Mosquito eggs were collected from various sites in Wisconsin and Minnesota. They were reared in the laboratory and adults were tested for LACV antigen by immunofluorescence assay. RNA was isolated from the abdomen of infected mosquitoes and portions of the small (S), medium (M) and large (L) viral genome segments were amplified by RT-PCR and sequenced. Overall, the viral sequences from 40 infected mosquitoes and 5 virus isolates were analyzed. Phylogenetic and linkage disequilibrium analyses revealed that approximately 25 % of infected mosquitoes and viruses contained reassorted genome segments, suggesting that LACV segment reassortment is frequent in nature. Background In the 1970s, La Crosse virus (LACV family Bunyaviridae
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Potential for La Crosse virus segment reassortment in nature.
Virology journal, 2008Co-Authors: Sara M. Reese, Bradley J. Blitvich, Carol D. Blair, Barry J. Beaty, Dave Geske, William C. BlackAbstract:The evolutionary success of La Crosse virus (LACV, family Bunyaviridae) is due to its ability to adapt to changing conditions through intramolecular genetic changes and segment reassortment. Vertical transmission of LACV in mosquitoes increases the potential for segment reassortment. Studies were conducted to determine if segment reassortment was occurring in naturally infected Aedes triseriatus from Wisconsin and Minnesota in 2000, 2004, 2006 and 2007. Mosquito eggs were collected from various sites in Wisconsin and Minnesota. They were reared in the laboratory and adults were tested for LACV antigen by immunofluorescence assay. RNA was isolated from the abdomen of infected mosquitoes and portions of the small (S), medium (M) and large (L) viral genome segments were amplified by RT-PCR and sequenced. Overall, the viral sequences from 40 infected mosquitoes and 5 virus isolates were analyzed. Phylogenetic and linkage disequilibrium analyses revealed that approximately 25% of infected mosquitoes and viruses contained reassorted genome segments, suggesting that LACV segment reassortment is frequent in nature.
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Selection of Refractory and Permissive Strains of Aedes triseriatus (Diptera: Culicidae) for Transovarial Transmission of La Crosse Virus
Journal of medical entomology, 1999Co-Authors: D. H. Graham, Barry J. Beaty, J. L. Holmes, S. Higgs, William C. BlackAbstract:The genetic basis of transovarial transmission of La Crosse virus in Aedes triseriatus (Say) was investigated through selection experiments on 2 mosquito strains. One strain was subject to selection for transovarial transmission refractoriness, the other for permissiveness to transovarial transmission. Response to selection for a low filial infection rate was rapid, decreasing from 18 to 3% in 3 generations. However, no response to selection for permissiveness was observed in the other strain; the average filial infection rates through 4 generations fluctuated between 25 and 40%. By contrast, the transovarial transmission rate in both strains showed a consistent response to selection in both directions. These patterns are consistent with a model in which transovarial transmission is controlled by a single genetic locus and permissiveness is conditioned by dominant alleles; whereas the filial infection rate is nongenetic and influenced by stochastic factors in the mosquito and virus.