Chemoprophylaxis vaccination with a Plasmodium liver stage autophagy mutant affords enhanced and long-lasting protection.

Genetically attenuated sporozoite vaccines can elicit long-lasting protection against malaria but pose risks of breakthrough infection. Chemoprophylaxis vaccination (CVac) has proven to be the most effective vaccine strategy against malaria. Here, we demonstrate that a liver stage-specific autophagy mutant of Plasmodium berghei (ATG8 overexpressor), when used as a live vaccine under a CVac regimen, provides superior long-lasting protection, in both inbred and outbred mice, as compared to WT-CVac. Uniquely, the protection elicited by this mutant is predominantly dependent on a CD8+ T-cell response through an IFN-γ-independent mechanism and is associated with a stable population of antigen-experienced CD8+ T cells. Jointly, our findings support the exploitation of liver-stage mutants as vaccines under a CVac protocol. This vaccination strategy is also a powerful model to study the mechanisms of protective immunity and discover new protective antigens.

An Improved Multiplex Polymerase Chain Reaction (PCR) Assay for the Identification of Mosquito (Diptera: Culicidae) Blood Meals.

The analysis of vertebrate blood meals serves as an integral component of vector incrimination studies where feeding preferences and host associations influence vector-borne disease transmission. Diagnostic polymerase chain reaction (PCR)-based techniques have been widely used to determine host associations, yet applications for Culex (Diptera: Culicidae), which feed primarily on bird populations, have been limited by multistep PCR techniques that approach each potential host species singly. As a result, we have developed a multiplexed primer set targeting mitochondrial cytochrome b sequences that can distinguish human, bird, and mammalian host blood meals in a single PCR reaction, an improvement over previous analyses relying on single primers or other multiplex primer approaches through the inclusion of avian primers. To validate this new methodology, we demonstrate its application on blood samples as well as field-collected Culex samples. Although designed for applications with mosquito vectors, this multiplex PCR assay is not mosquito-specific, and should serve as a valuable tool for identifying the blood meals of other blood-feeding arthropods, contributing greatly to the study of vector-borne disease.

Long-term surveillance defines spatial and temporal patterns implicating Culex tarsalis as the primary vector of West Nile virus.

West Nile virus (WNV) has become the most epidemiologically important mosquito-borne disease in the United States, causing ~50,000 cases since its introduction in 1999. Transmitted primarily by Culex species, WNV transmission requires the complex interplay between bird reservoirs and mosquito vectors, with human cases the result of epizootic spillover. To better understand the intrinsic factors that drive these interactions, we have compiled infection data from sentinel chickens, mosquito vectors, and human cases in Iowa over a 15 year period (2002-2016) to better understand the spatial and temporal components that drive WNV transmission. Supplementing these findings with mosquito abundance, distribution, and host preferences data, we provide strong support that Culex tarsalis is the most important vector of human WNV infections in the region. Together, our analysis provides new insights into WNV infection patterns in multiple hosts and highlights the importance of long-term surveillance to understand the dynamics of mosquito-borne-disease transmission.