scholarly journals Investigation of Biological Factors Contributing to Individual Variation in Viral Titer after Oral Infection of Aedes aegypti Mosquitoes by Sindbis Virus

Viruses ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 131
Author(s):  
Peter Hodoameda ◽  
Linus Addae ◽  
Rollie J. Clem
Keyword(s):  
Aedes Aegypti ◽  
Sindbis Virus ◽  
Vector Competence ◽  
High Titer ◽  
Mosquito Species ◽  
Virus Titer ◽  
Laboratory Strain ◽  
Virus Concentration ◽  
Biological Factors ◽  
Single Experiment

The mechanisms involved in determining arbovirus vector competence, or the ability of an arbovirus to infect and be transmitted by an arthropod vector, are still incompletely understood. It is well known that vector competence for a particular arbovirus can vary widely among different populations of a mosquito species, which is generally attributed to genetic differences between populations. What is less understood is the considerable variability (up to several logs) that is routinely observed in the virus titer between individual mosquitoes in a single experiment, even in mosquitoes from highly inbred lines. This extreme degree of variation in the virus titer between individual mosquitoes has been largely ignored in past studies. We investigated which biological factors can affect titer variation between individual mosquitoes of a laboratory strain of Aedes aegypti, the Orlando strain, after Sindbis virus infection. Greater titer variation was observed after oral versus intrathoracic infection, suggesting that the midgut barrier contributes to titer variability. Among the other factors tested, only the length of the incubation period affected the degree of titer variability, while virus strain, mosquito strain, mosquito age, mosquito weight, amount of blood ingested, and virus concentration in the blood meal had no discernible effect. We also observed differences in culture adaptability and in the ability to orally infect mosquitoes between virus populations obtained from low and high titer mosquitoes, suggesting that founder effects may affect the virus titer in individual mosquitoes, although other explanations also remain possible.

scholarly journals Colonized Sabethes cyaneus, a Sylvatic New World Mosquito Species, Shows a Low Vector Competence for Zika Virus Relative to Aedes aegypti

Viruses ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 434 ◽  
Author(s):  
Ajit K. Karna ◽  
Sasha R. Azar ◽  
Jessica A. Plante ◽  
Rumei Yun ◽  
Nikos Vasilakis ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Yellow Fever ◽  
Zika Virus ◽  
New World ◽  
Yellow Fever Virus ◽  
Vector Competence ◽  
Mosquito Species ◽  
Sylvatic Cycle ◽  
Post Feeding ◽  
Body Compartments

The introduction of Zika virus (ZIKV) to the Americas raised concern that the virus would spill back from human transmission, perpetuated by Aedes aegypti, into a sylvatic cycle maintained in wildlife and forest-living mosquitoes. In the Americas, Sabethes species are vectors of sylvatic yellow fever virus (YFV) and are therefore candidate vectors of a sylvatic ZIKV cycle. To test the potential of Sabethes cyaneus to transmit ZIKV, Sa. cyaneus and Ae. aegypti were fed on A129 mice one or two days post-infection (dpi) with a ZIKV isolate from Mexico. Sa. cyaneus were sampled at 3, 4, 5, 7, 14, and 21 days post-feeding (dpf) and Ae. aegypti were sampled at 14 and 21 dpf. ZIKV was quantified in mosquito bodies, legs, and saliva to measure infection, dissemination, and potential transmission, respectively. Of 69 Sa. cyaneus that fed, ZIKV was detected in only one, in all body compartments, at 21 dpf. In contrast, at 14 dpf 100% of 20 Ae. aegypti that fed on mice at 2 dpi were infected and 70% had virus in saliva. These data demonstrate that Sa. cyaneus is a competent vector for ZIKV, albeit much less competent than Ae. aegypti.

scholarly journals Rapid selection against arbovirus-induced apoptosis during infection of a mosquito vector

2015 ◽  
Vol 112 (10) ◽  
pp. E1152-E1161 ◽  
Author(s):  
Katelyn O’Neill ◽  
Bradley J. S. C. Olson ◽  
Ning Huang ◽  
Dave Unis ◽  
Rollie J. Clem
Keyword(s):  
Sindbis Virus ◽  
Vector Competence ◽  
Mosquito Species ◽  
Infected Mosquito ◽  
Nucleotide Sequencing ◽  
Mosquito Vector ◽  
Antiviral Defense ◽  
Mosquito Cells ◽  
Arbovirus Infection ◽  
Induced Apoptosis

Millions of people are infected each year by arboviruses (arthropod-borne viruses) such as chikungunya, dengue, and West Nile viruses, yet for reasons that are largely unknown, only a relatively small number of mosquito species are able to transmit arboviruses. Understanding the complex factors that determine vector competence could facilitate strategies for controlling arbovirus infections. Apoptosis is a potential antiviral defense response that has been shown to be important in other virus–host systems. However, apoptosis is rarely seen in arbovirus-infected mosquito cells, raising questions about its importance as an antiviral defense in mosquitoes. We tested the effect of stimulating apoptosis during arbovirus infection by infectingAedes aegyptimosquitoes with a Sindbis virus (SINV) clone called MRE/Rpr, in which the MRE-16 strain of SINV was engineered to express the proapoptotic genereaperfromDrosophila. MRE/Rpr exhibited an impaired infection phenotype that included delayed midgut infection, delayed virus replication, and reduced virus accumulation in saliva. Nucleotide sequencing of thereaperinsert in virus populations isolated from individual mosquitoes revealed evidence of rapid and strong selection against maintenance of Reaper expression in MRE/Rpr-infected mosquitoes. The impaired phenotype of MRE/Rpr, coupled with the observed negative selection against Reaper expression, indicates that apoptosis is a powerful defense against arbovirus infection in mosquitoes and suggests that arboviruses have evolved mechanisms to avoid stimulating apoptosis in mosquitoes that serve as vectors.

scholarly journals Anopheles Mosquitoes May Drive Invasion and Transmission of Mayaro Virus across Geographically Diverse Regions

2018 ◽  
Author(s):  
Marco Brustolin ◽  
Sujit Pujhari ◽  
Cory A. Henderson ◽  
Jason L. Rasgon
Keyword(s):  
South America ◽  
Aedes Aegypti ◽  
Culex Quinquefasciatus ◽  
Vector Competence ◽  
Mosquito Species ◽  
Anopheles Mosquitoes ◽  
The World ◽  
The Caribbean ◽  
Geographic Regions ◽  
Mayaro Virus

AbstractThe Togavirus (Alphavirus) Mayaro virus (MAYV) was initially described in 1954 from Mayaro County (Trinidad) and has been responsible for outbreaks in South America and the Caribbean. Imported MAYV cases are on the rise, leading to invasion concerns similar to Chikungunya and Zika viruses. Little is known about the range of mosquito species that are competent MAYV vectors. We tested vector competence of 2 MAYV genotypes for six mosquito species (Aedes aegypti, Anopheles gambiae, An. stephensi, An. quadrimaculatus, An. freeborni, Culex quinquefasciatus). Ae. aegypti and Cx. quinquefasciatus were poor MAYV vectors, and either were poorly infected or poorly transmitted. In contrast, all Anopheles species were able to transmit MAYV, and 3 of the 4 species transmitted both genotypes. The Anopheles species tested are divergent and native to widely separated geographic regions, suggesting that Anopheles may be important in the invasion and spread of MAYV across diverse regions of the world.

scholarly journals Temperature and Sugar Feeding Effects on the Activity of a Laboratory Strain of Aedes aegypti

Insects ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 347 ◽  
Author(s):  
Irvin Forde Upshur ◽  
Elizabeth Annadel Bose ◽  
Cameron Hart ◽  
Chloé Lahondère
Keyword(s):  
Aedes Aegypti ◽  
Mosquito Species ◽  
Thermal Conditions ◽  
Laboratory Strain ◽  
Blood Feeding ◽  
Effect Of Temperature ◽  
Total Carbohydrate ◽  
Sugar Feeding ◽  
Host Seeking ◽  
Invasive Mosquito

Aedes aegypti is an invasive mosquito species that is expected to expand its global distribution through climate change. As poikilotherms, mosquitoes are greatly affected by the temperature of the environment which can impact host-seeking, blood-feeding, and flight activity as well as survival and ability to transmit pathogens. However, an important aspect of mosquito biology on which the effect of temperature has not been investigated is water and sugar-feeding and how access to a sugar source might affect the insect’s activity and survival under different thermal conditions. To close this knowledge gap, we relied on actometer experiments to study the activity of both female and male Ae. aegypti at 20 °C, 25 °C, and 30 °C, providing either water or 10% sucrose to the insects. We then measured the total carbohydrate contents of alive mosquitoes using the anthrone protocol. Survival was assessed and compared between all groups. Results from this study will inform on the thermal biology of Ae. aegypti mosquitoes and how access to sugar affects their activity.

scholarly journals Evaluation of Mosquito Attractant Candidates Using a High-Throughput Screening System for Aedes aegypti (L.), Culex quinquefasciatus Say. and Anopheles minimus Theobald (Diptera: Culicidae)

Insects ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 528
Author(s):  
Dae-Yun Kim ◽  
Theerachart Leepasert ◽  
Michael J. Bangs ◽  
Theeraphap Chareonviriyaphap
Keyword(s):  
Lactic Acid ◽  
Aedes Aegypti ◽  
High Throughput ◽  
Culex Quinquefasciatus ◽  
High Throughput Screening ◽  
Mosquito Species ◽  
Laboratory Strain ◽  
Screening System ◽  
Anopheles Minimus ◽  
Significant Difference

Several types of olfactometers have been used to evaluate mosquito responses to agents that mimic natural volatiles that repel or attract. The Y-tube olfactometer has been widely used to study repellents and attractants, while the high-throughput screening system assay has only been used to study repellents. Whether the high-throughput screening system assay is suitable for evaluating attractants is unknown. We evaluated the responses to four lactic-acid-based mixtures and two non-lactic-acid-based chemical lure candidates using the high-throughput screening system (HITSS) for three mosquito species (laboratory strains and field populations of both Aedes aegypti (L.) and Culex quinquefasciatus Say.; laboratory strain of Anopheles minimus Theobald) under laboratory-controlled conditions. HITSS assay results showed that KU-lure #1 elicited the greatest percent attraction for pyrethroid-resistant and -susceptible Ae. aegypti. KU-lure #6 elicited the strongest attractive response for pyrethroid-susceptible and -resistant Cx. quinquefasciatus and pyrethroid-susceptible An. minimus. The response to the lures from each species was independent of the pyrethroid susceptibility status (Ae. aegypti, p = 0.825; Cx. quinquefasciatus, p = 0.056). However, a significant difference in attraction to KU-lure #6 was observed between diurnal and nocturnal mosquitoes (Cx. quinquefasciatus vs. Ae. aegypti, p = 0.014; An. minimus vs. Ae. aegypti, p = 0.001). The laboratory-level HITSS assay effectively selects potential lure candidates. Because the host-seeking behavior differs between mosquito species, further studies are needed to develop species-specific attractants. Additional studies in semi-field screen houses using commercial traps are necessary to evaluate the accuracy of these laboratory assay results.

scholarly journals Transmission potential of Floridian Aedes aegypti mosquitoes for dengue virus serotype 4: Implications for estimating local dengue risk

2021 ◽  
Author(s):  
Caroline J. Stephenson ◽  
Heather Coatsworth ◽  
Seokyoung Kang ◽  
John A. Lednicky ◽  
Rhoel R. Dinglasan
Keyword(s):  
Aedes Aegypti ◽  
Dengue Virus ◽  
Vector Competence ◽  
Field Isolate ◽  
Laboratory Strain ◽  
The State ◽  
Transmission Risk ◽  
Transmission Potential ◽  
Virus Serotype ◽  
Index Cases

AbstractDengue virus serotype 4 (DENV-4) circulated in Aedes aegypti in 2016 and 2017 in Florida in the absence of human index cases, compelling a full assessment of local mosquito vector competence and DENV-4 risk. To better understand DENV-4 transmission risk in Florida, we used an expanded suite of tests to measure and compare the vector competence of both an established colony of Ae. aegypti (Orlando strain [ORL]) and a field-derived colony from Collier County, Florida in 2018 (COL) for a Haitian DENV-4 human field isolate and a DENV-4 laboratory strain (Philippines H241). We immediately noted that ORL saliva-positivity was higher for the field versus laboratory DENV-4 strains. In a subsequent comparison with the recent COL mosquito colony we also observed significantly higher midgut susceptibility of COL and ORL for the Haitian DENV-4 field strain, and significantly higher saliva-positivity rate for COL, although overall saliva virus titers were similar between the two. These data point to a potential midgut infection barrier for the DENV-4 laboratory strain for both mosquito colonies and that the marked difference in transmission potential estimates hinge on virus-vector combinations. Our study highlights the importance of leveraging an expanded suite of testing methods with emphasis on utilizing local mosquito populations and field relevant dengue serotypes and strains to accurately estimate transmission risk in a given setting.ImportanceDENV-4 was found circulating in Florida (FL) Ae. aegypti mosquitoes in the absence of human index cases in the state (2016-2017). How DENV-4 was maintained locally is unclear, presenting a major gap in our understanding of DENV-4 public health risk. We determined the baseline arbovirus transmission potential of laboratory and field colonies of Ae. aegypti for both laboratory and field isolates of DENV-4. We observed high transmission potential of field populations of Ae. aegypti and evidence of higher vertical transmission of the DENV-4 field isolate, providing clues to the possible mechanism of undetected DENV-4 maintenance in the state. Our findings also move the field forward in the development of best practices for evaluating arbovirus vector competence, with evidence that transmission potential estimates vary depending on the mosquito-virus combinations. These data emphasize the poor suitability of lab-established virus strains and the high relevance of field-derived mosquito populations in estimating transmission risk.

scholarly journals Vector competence of selected North AmericanAnophelesandCulexmosquitoes for Zika virus

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4324 ◽  
Author(s):  
Brittany L. Dodson ◽  
Sujit Pujhari ◽  
Jason L. Rasgon
Keyword(s):  
North America ◽  
Aedes Aegypti ◽  
Zika Virus ◽  
Vector Competence ◽  
Mosquito Species ◽  
Culex Tarsalis ◽  
Anopheles Quadrimaculatus ◽  
Vector Borne ◽  
Serious Disease ◽  
Blood Meals

Zika virus (ZIKV) is a vector-borne flavivirus that has caused recent outbreaks associated with serious disease in infants and newborns in the Americas.Aedesmosquitoes are the primary vectors for ZIKV, but little is known about the diversity of mosquitoes that can transmit ZIKV in North America. We chose three abundant North American mosquito species (Anopheles freeborni,Anopheles quadrimaculatus, andCulex tarsalis) and one known vector species (Aedes aegypti), fed them blood meals supplemented with a recent outbreak ZIKV strain, and tested bodies, legs, and saliva for infectious ZIKV. ZIKV was able to infect, disseminate, and be transmitted byAedes aegypti. However,Anopheles freeborni,Anopheles quadrimaculatus, andCulex tarsaliswere unable to be infected. We conclude that these species are unlikely to be involved in ZIKV transmission in North America. However, we should continue to examine the ability for other mosquito species to potentially act as ZIKV vectors in North America.

scholarly journals Variation in Tomato spotted wilt virus Titer in Frankliniella occidentalis and Its Association with Frequency of Transmission

2009 ◽  
Vol 99 (4) ◽  
pp. 404-410 ◽  
Author(s):  
Dorith Rotenberg ◽  
Nallur K. Krishna Kumar ◽  
Diane E. Ullman ◽  
Mauricio Montero-Astúa ◽  
David K. Willis ◽  
...  
Keyword(s):  
Time Course ◽  
Tomato Spotted Wilt Virus ◽  
Frankliniella Occidentalis ◽  
Vector Competence ◽  
High Titer ◽  
Virus Titer ◽  
Quantitative Relationship ◽  
Adult Eclosion ◽  
Tomato Spotted Wilt ◽  
Wilt Virus

Tomato spotted wilt virus (TSWV) is transmitted in a persistent propagative manner by Frankliniella occidentalis, the western flower thrips. While it is well established that vector competence depends on TSWV acquisition by young larvae and virus replication within the insect, the biological factors associated with frequency of transmission have not been well characterized. We hypothesized that the number of transmission events by a single adult thrips is determined, in part, by the amount of virus harbored (titer) by the insect. Transmission time-course experiments were conducted using a leaf disk assay to determine the efficiency and frequency of TSWV transmission following 2-day inoculation access periods (IAPs). Virus titer in individual adult thrips was determined by real-time quantitative reverse transcriptase-PCR (qRT-PCR) at the end of the experiments. On average, 59% of adults transmitted the virus during the first IAP (2 to 3 days post adult-eclosion). Male thrips were more efficient at transmitting TSWV multiple times compared with female thrips of the same cohort. However, females harbored two to three times more copies of TSWV-N RNA per insect, indicating that factors other than absolute virus titer in the insect contribute to a successful transmission event. Examination of virus titer in individual insects at the end of the third IAP (7 days post adult-eclosion) revealed significant and consistent positive associations between frequency of transmission and virus titer. Our data support the hypothesis that a viruliferous thrips is more likely to transmit multiple times if it harbors a high titer of virus. This quantitative relationship provides new insights into the biological parameters that may influence the spread of TSWV by thrips.

scholarly journals Expressing the pro-apoptotic Reaper protein via insertion into the structural open reading frame of Sindbis virus reduces the ability to infect Aedes aegypti mosquitoes

2022 ◽  
Author(s):  
Alexis Carpenter ◽  
Rollie J Clem
Keyword(s):  
Aedes Aegypti ◽  
Sindbis Virus ◽  
Cultured Cells ◽  
Virus Titer ◽  
Open Reading Frame ◽  
Infection Prevalence ◽  
Reading Frame ◽  
Disseminated Infection ◽  
Control Virus ◽  
Induced Apoptosis

Arboviruses continue to threaten a significant portion of the human population, and a better understanding is needed of the determinants of successful arbovirus infection of arthropod vectors. Avoiding apoptosis has been shown to be one such determinant. Previous work showed that a Sindbis virus (SINV) construct called MRE/rpr that expresses the pro-apoptotic protein Reaper via a duplicated subgenomic promoter had a reduced ability to orally infect Aedes aegypti mosquitoes at 3 days post-blood meal (PBM), but this difference diminished over time as virus variants containing deletions in the inserted reaper gene rapidly predominated. The goal of this study was to generate a SINV construct that more stably expressed Reaper, in order to further clarify the effect of midgut apoptosis on disseminated infection in Ae. aegypti. We did this by inserting reaper as an in-frame fusion into the structural open reading frame (ORF) of SINV. This construct, MRE/rprORF, successfully expressed Reaper, replicated similarly to MRE/rpr in cell lines, and induced apoptosis in cultured cells and in mosquito midgut tissue. Mosquitoes that fed on blood containing MRE/rprORF developed less midgut and disseminated infection when compared to MRE/rpr or a control virus up to at least 7 days PBM, when less than 50% of mosquitoes that ingested MRE/rprORF had detectable disseminated infection, compared with around 80% or more of mosquitoes fed with MRE/rpr or control virus. However, virus titer in mosquitoes infected with MRE/rprORF was not significantly different from control virus, suggesting that induction of apoptosis by expression of Reaper by this method can reduce infection prevalence, but if infection is established then apoptosis induced by this method has limited ability to continue to suppress replication.

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