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Mosquito Diversity, Range-Expanding Species, and Host-Feeding Patterns Across Virginia's Heterogeneous Landscapes

Understanding how mosquito community, host use, and environmental drivers vary across landscapes is critical for predicting vector‑borne disease risk. Virginia spans multiple ecoregions and broad elevational gradient, yet statewide surveillance remains limited and concentrated near urban centers. To address surveillance gaps, we surveyed mosquitoes across four ecologically distinct sites in Virginia during 2022 to evaluate species diversity, bloodfeeding patterns, and environmental predictors of occurrence. Using CDC light traps, gravid traps, and supplemental aspiration, we collected 7,781 mosquitoes representing 34 species. Community composition varied significantly among sites: the Coastal Plain exhibited the greatest abundance and richness, while montane and urban sites supported lower but distinct assemblages. Several medically important and invasive species—including Aedes albopictus (Skuse), Aedes japonicus (Theobald), Culex pipiens/quinquefasciatus, Culiseta inornata (Williston), and the range-expanding Culex coronator (Dyar & Knab) and Culex nigripalpus (Theobald) were detected, providing new regional records beyond previously documented localities. Bloodmeal analysis from 18 specimens revealed predominantly mammalian feeding, with white‑tailed deer (Odocoileus virginianus [Zimmermann]) comprising over 80% of identified hosts across taxa. Avian and amphibian hosts occurred at lower frequencies, indicating diverse host–vector interactions relevant to enzootic transmission. Random forest models identified elevation and trap type as the strongest predictors of species-specific occurrence, with climatic factors exerting secondary effects. Together, these findings show that mosquito distribution and host selection in Virginia are shaped by interacting ecological and environmental drivers, underscoring the need for expanded, ecologically informed surveillance to improve assessments of vector‑borne disease risk in the region.

RESEARCH NOTE: Exploring the Competence of Various Poultry Species for Cache Valley virus InfectionCache Valley virus (CVV) belongs to the genus Orthobunyavirus, and is known to cause severe disease in ruminants, including spontaneous abortions and …

Humoral and T-cell-mediated responses to an insect-specific flavivirus-based Zika virus vaccine candidate - PubMedFlaviviruses represent a significant global health threat and relatively few licensed vaccines exist to protect against them. Insect-specific flaviviruses (ISFVs) are incapable of replication in humans and have emerged as a novel and promising tool for flavivirus vaccine development. ISFV-based flav …

Ecology and geography of Cache Valley virus assessed using ecological niche modeling

Cache Valley virus (CVV) is an understudied Orthobunyavirus with a high spillover transmission potential due to its wide geographical distribution and large number of associated hosts and vectors. Although CVV is known to be widely distributed throughout North America, no studies have explored its geography or employed computational methods to explore the mammal and mosquito species likely participating in the CVV sylvatic cycle. We used a literature review and online databases to compile locality data for CVV and its potential vectors and hosts. We linked location data points with climatic data via ecological niche modeling to estimate the geographical range of CVV and hotspots of transmission risk. We used background similarity tests to identify likely CVV mosquito vectors and mammal hosts to detect ecological signals from CVV sylvatic transmission. CVV distribution maps revealed a widespread potential viral occurrence throughout North America. Ecological niche models identified areas with climate, vectors, and hosts suitable to maintain CVV transmission. Our background similarity tests identified Aedes vexans, Culiseta inornata, and Culex tarsalis as the most likely vectors and Odocoileus virginianus (white-tailed deer) as the most likely host sustaining sylvatic transmission. CVV has a continental-level, widespread transmission potential. Large areas of North America have suitable climate, vectors, and hosts for CVV emergence, establishment, and spread. We identified geographical hotspots that have no confirmed CVV reports to date and, in view of CVV misdiagnosis or underreporting, can guide future surveillance to specific localities and species.

Exploring the immunogenicity of an insect-specific virus vectored Zika vaccine candidate

Zika virus (ZIKV) is an important re-emerging flavivirus that presents a significant threat to human health worldwide. Despite its importance, no vaccines are approved for use in humans. Insect-specific flaviviruses (ISFVs) have recently garnered attention as an antigen presentation platform for vaccine development and diagnostic applications. Here, we further explore the safety, immunogenicity, and efficacy of a chimeric ISFV-Zika vaccine candidate, designated Aripo-Zika (ARPV/ZIKV). Our results show a near-linear relationship between increased dose and immunogenicity, with 1011 genome copies (i.e., 108 focus forming units) being the minimum dose required for protection from ZIKV-induced morbidity and mortality in mice. Including boosters did not significantly increase the short-term efficacy of ARPV/ZIKV-vaccinated mice. We also show that weanling mice derived from ARPV/ZIKV-vaccinated dams were completely protected from ZIKV-induced morbidity and mortality upon challenge, suggesting efficient transfer of maternally-derived protective antibodies. Finally, in vitro coinfection studies of ZIKV with Aripo virus (ARPV) and ARPV/ZIKV in African green monkey kidney cells (i.e., Vero-76) showed that ARPV and ARPV/ZIKV remain incapable of replication in vertebrate cells, despite the presence of active ZIKV replication. Altogether, our data continue to support ISFV-based vaccines, and specifically the ARPV backbone is a safe, immunogenic and effective vaccine strategy for flaviviruses.

Phylogenetic characterization of Orthobunyaviruses isolated from Trinidad shows evidence of natural reassortment - Virus GenesThe genus Orthobunyavirus is a diverse group of viruses in the family Peribunyaviridae, recently classified into 20 serogroups, and 103 virus species. Although most viruses within these serogroups are phylogenetically distinct, the absence of complete genome sequences has left several viruses incompletely characterized. Here we report the complete genome sequences for 11 orthobunyaviruses isolated from Trinidad, French Guiana, Guatemala, and Panama that were serologically classified into six serogroups and 10 species. Phylogenetic analyses of these 11 newly derived sequences indicate that viruses belonging to the Patois, Capim, Guama, and Group C serocomplexes all have a close genetic origin. We show that three of the 11 orthobunyaviruses characterized (belonging to the Group C and Bunyamwera serogroups) have evidence of histories of natural reassortment through the M genome segment. Our data also suggests that two distinct lineages of Group C viruses concurrently circulate in Trinidad and are transmitted by the same mosquito vectors. This study also highlights the importance of complementing serological identification with nucleotide sequencing when characterizing orthobunyaviruses.

Dynamics of parasite growth in genetically diverse Plasmodium falciparum isolatesMultiple parasite lineages with different proliferation rates or fitness may coexist within a clinical malaria isolate, resulting in complex growth in…

A Gamma-adapted recombinant subunit vaccine induces broadly neutralizing antibodies against SARS-CoV-2 variants and protects mice from infectionThe COVID-19 pandemic continues with the emergence of successive new variants of concern (VOC). One strategy to prevent breakthrough infections is developing safe and effective broad-spectrum vaccines. Here, we present preclinical studies of a RBD recombinant vaccine candidate derived from the Gamma SARS-CoV-2 variant adjuvanted with alum. Gamma RBD-derived antigen elicited better neutralizing antibody and T cell responses than formulation containing ancestral RBD antigen. The Gamma-adapted subunit vaccine elicited a long-lasting antibody response with cross-neutralizing activity against different VOC including the Omicron variant. Additionally, Gamma variant RBD-adapted vaccine elicited robust T cells responses with induction of Th1 and CD8+ T cell responses in spleen and lung. Vaccine-induced immunity protected K18-hACE2 mice from intranasal challenge with SARS-CoV-2 increasing survival, reducing body weight loss and viral burden in the lungs and brain. Importantly, the subunit vaccine demonstrated a potent effect as heterologous booster of different vaccine platforms including the non-replicating adenovirus vaccine ChAdOx1-S, the mRNA vaccine BNT162b2 and the inactivated SARS-CoV-2 vaccine BBIBP-CorV, increasing cross-reactive antibody responses. Our study indicates that the adjuvanted Gamma RBD vaccine is highly immunogenic and a broad-spectrum vaccine candidate to combat SARS-CoV-2 variants including Omicron. ### Competing Interest Statement J.M.R., A.C.HI., F.M.Z. are salaried employees of Fundacion Pablo Cassara. S.A.DP., I.G.K., A.V.DN., V.K., I.D., C.J.P., J.A.B., J.E.S., M.LC J.M.F. and J.C.V. are salaried employees of Laboratorio Pablo Cassara. L.M.C., J.C., K.A.P., D.E.A., A.D., C.P.C., L.A.B, L.M.S., L.P., M.R.M., E.F.C. A.J.A. and W.B.S. declare no competing interests relevant to this article.

A Novel Bacterial Protease Inhibitor Adjuvant in RBD-Based COVID-19 Vaccine Formulations Containing Alum Increases Neutralizing Antibodies, Specific Germinal Center B Cells and Confers Protection Against SARS-CoV-2 Infection in MiceIn this work, we evaluated recombinant receptor binding domain (RBD)-based vaccine formulation prototypes with potential for further clinical development. We assessed different formulations containing RBD plus alum, AddaS03, AddaVax, or the combination of alum and U-Omp19: a novel Brucella spp. protease inhibitor vaccine adjuvant. Results show that the vaccine formulation composed of U-Omp19 and alum as adjuvants has a better performance: it significantly increased mucosal and systemic neutralizing antibodies in comparison to antigen plus alum, AddaVax, or AddaS03. Antibodies induced with the formulation containing U-Omp19 and alum not only increased their neutralization capacity against the ancestral virus but also cross-neutralized alpha, lambda, and gamma variants with similar potency. Furthermore, the addition of U-Omp19 to alum vaccine formulation increased the frequency of RBD-specific geminal center B cells and plasmablasts. Additionally, U-Omp19+alum formulation induced RBD-specific Th1 and CD8+ T-cell responses in spleens and lungs. Finally, this vaccine formulation conferred protection against an intranasal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) challenge of K18-hACE2 mice.

La Crosse Virus Shows Strain-Specific Differences in PathogenesisLa Crosse virus (LACV) is the leading cause of pediatric viral encephalitis in North America, and is an important public health pathogen. Historically, studies involving LACV pathogenesis have focused on lineage I strains, but no former work has explored the pathogenesis between or within lineages. Given the absence of LACV disease in endemic regions where a robust entomological risk exists, we hypothesize that some LACV strains are attenuated and demonstrate reduced neuroinvasiveness. Herein, we compared four viral strains representing all three lineages to determine differences in neurovirulence or neuroinvasiveness using three murine models. A representative strain from lineage I was shown to be the most lethal, causing >50% mortality in each of the three mouse studies. However, other strains only presented excessive mortality (>50%) within the suckling mouse neurovirulence model. Neurovirulence was comparable among strains, but viruses differed in their neuroinvasive capacities. Our studies also showed that viruses within lineage III vary in pathogenesis with contemporaneous strains, showing reduced neuroinvasiveness compared to an ancestral strain from the same U.S. state (i.e., Connecticut). These findings demonstrate that LACV strains differ markedly in pathogenesis, and that strain selection is important for assessing vaccine and therapeutic efficacies.

Novel murine models for studying Cache Valley virus pathogenesis and in utero transmissionCache Valley virus (CVV) is a prevalent emerging pathogen of significant importance to agricultural and human health in North America. Emergence in livestock can result in substantial agroeconomic ...

Enemy of My Enemy: A Novel Insect-Specific Flavivirus Offers a Promising Platform for a Zika Virus VaccineVaccination remains critical for viral disease outbreak prevention and control, but conventional vaccine development typically involves trade-offs between safety and immunogenicity. We used a recently discovered insect-specific flavivirus as a vector in order to develop an exceptionally safe, flavivirus vaccine candidate with single-dose efficacy. To evaluate the safety and efficacy of this platform, we created a chimeric Zika virus (ZIKV) vaccine candidate, designated Aripo/Zika virus (ARPV/ZIKV). ZIKV has caused immense economic and public health impacts throughout the Americas and remains a significant public health threat. ARPV/ZIKV vaccination showed exceptional safety due to ARPV/ZIKV’s inherent vertebrate host-restriction. ARPV/ZIKV showed no evidence of replication or translation in vitro and showed no hematological, histological or pathogenic effects in vivo. A single-dose immunization with ARPV/ZIKV induced rapid and robust neutralizing antibody and cellular responses, which offered complete protection against ZIKV-induced morbidity, mortality and in utero transmission in immune-competent and -compromised murine models. Splenocytes derived from vaccinated mice demonstrated significant CD4+ and CD8+ responses and significant cytokine production post-antigen exposure. Altogether, our results further support that chimeric insect-specific flaviviruses are a promising strategy to restrict flavivirus emergence via vaccine development.

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