Dissecting vectorial capacity for mosquito-borne viruses

Abstract

The inter-relationship between mosquitoes and the viruses they transmit is complex. While previously understood barriers to infection and transmission remain valid, additional factors have been uncovered that suggest an “arms race” between mosquito and virus. These include the mosquito microbiota and interplay between mosquito and viral genetics. Following an infectious blood meal, the mosquito mounts an immune and transcriptional response, leading to altered expression of multiple genes. These complex interactions, specific to vector and virus genotypes, combine with external influences, particularly temperature, to determine vector competence. The mosquito’s response to the infecting agent may have consequences in terms of longevity, feeding behavior and/or fecundity. These factors, together with population density and the frequency of host contact determine vectorial capacity.

Experimental risk assessment for chikungunya virus transmission based on vector competence, distribution and temperature suitability in Europe, 2018

“…In addition, one must keep in mind that vector competence is an important parameter of vector capacity, but it is not the only one. Vector capacity is determined by a complex interaction between different factors [30]. Important drivers include the population density and host-feeding patterns.…”

Invasiveness ofAedes aegyptiandAedes albopictusand Vectorial Capacity for Chikungunya Virus

“…This section concentrates on selected components of virus-vector-vertebrate (human) interrelationships, focusing specifically on how interactions between vector, virus, and environment shape the patterns and intensity of transmission of one of the important viral pathogens mentioned above, CHIKV. Mosquito-borne disease outbreaks are influenced by intrinsic (eg, vector and viral genetics, vector and host competence, and vector life-history traits) and extrinsic (eg, temperature, rainfall, and human land use) factors that affect virus activity and mosquito biology in complex and interconnected ways (Figure 1) [31]. Disease prevalence varies spatially and temporally, depending on VC, a concept that integrates intrinsic and extrinsic factors to address interactions of the virus with the arthropod and human host.…”

“…In contrast, host feeding (a), vector longevity ( p), and EIP (n) would influence R 0 much more powerfully (eg, as a square or exponent). It seems to follow that virus infectivity for mosquitoes, which would be incorporated into VC as b, would be of relatively minor importance as compared to viral factors, such as the speed of dissemination from the midgut, that would impact the duration of the EIP, which would influence VC as n [31]. Thus, natural selection might favor a poorly infectious but rapidly disseminating virus over a highly infectious virus that disseminates slowly.…”

Plant Virus–Insect Vector Interactions: Current and Potential Future Research Directions

“…While mosquito-borne viruses are commonly pathogenic to their vertebrate host, biological infection of the insect host has few major pathogenic impacts on the insect host, allowing efficient transmission of the virus by the insect vector [116]. The virus can however have some impact on the mosquito fitness and recent studies indicate that there is an intricate interaction between virus and vector, which can influence vector competence (reviewed in [117]). A number of factors can contribute to the control of virus infection within the mosquito host, which in turn impact virus transmission to the vertebrate host.…”

“…A number of factors can contribute to the control of virus infection within the mosquito host, which in turn impact virus transmission to the vertebrate host. In addition to the mosquito infection barriers [115,117], the mosquito innate immune system includes the intrinsic RNAi pathway and several inducible systems, including Toll, immune deficiency (IMD) and Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathways [116,118,119]. The Drosophila model system has been used to identify many of these antiviral immune pathways [120,121], but interestingly many of the Drosophila viruses can be highly pathogenic to their host.…”