Biology subjects

Christofferson, R. C.

Publications and source records attributed to Christofferson, R. C..

4 recordsLinked to original sources

bioRxiv2024

The good, the BATV, and the ugly - first report of BATV vector competence in Culex quinquefasciatus from the Southern United States

Batai virus is an arbovirus with wide geographic, host, and climactic ranges. BATV infects primarily avian species but can cause disease in ruminants and humans. Louisiana is at particular risk for overlaps in natural and agricultural systems as the Mississippi Flyway passes through the state. We assessed the vector competence of Louisiana Cx. quinquefasciatus for BATV and found infection and dissemination rates of 22% and 11.1% at 7 days post-exposure (dpe), and 15.8% and 5.3% at 21dpe. The current H5N1 avian influenza outbreak in dairy cows demonstrates the importance of understanding the overlap in avian and other vertebrate species to inform public health and agricultural biosecurity. Results indicate a moderate vector competence of regional Louisiana Cx. quinquefasciatus for BATV. This study presents the first known report of vector competence of BATV in US mosquitoes and establishes the non-zero risk of its emergence in the southern US.

ecology↗

bioRxiv2022

Exploring the mosquito-arbovirus network: a survey of vector competence experiments

Arboviruses receive heightened research attention during major outbreaks, or when they cause unusual or severe clinical disease, but are otherwise under-characterized. Global change is also accelerating the emergence and spread of arboviral diseases, leading to time sensitive questions about potential interactions between viruses and novel vectors. Vector competence experiments help determine the susceptibility of certain arthropods to a given arbovirus, but these experiments are often conducted in real-time during outbreaks, rather than with preparedness in mind. We conducted a systematic review of reported mosquito-arbovirus competence experiments, screening 570 abstracts to arrive at 265 studies testing in vivo arboviral competence. We found that over 90% of potential mosquito-virus combinations are untested in experimental settings, and that entire regions and their corresponding vectors and viruses are undersampled. These knowledge gaps stymie outbreak response, and limit attempts to both build and validate predictive models of the vector-virus network.

ecology↗

bioRxiv2021

How do I bite thee? Let me count the ways: Heterogeneity and temperature dependence in Ae. aegypti biting habits drive individual mosquito arbovirus transmission potential

In models of mosquito-borne transmission, the mosquito biting rate is an influential parameter, and understanding the heterogeneity of the process of biting is important, as biting is usually assumed to be relatively homogeneous across individuals, with time-between-bites described by an exponentially distributed process. However, these assumptions have not been addressed through laboratory experimentation. We experimentally investigated the daily biting habits of Ae. aegypti at three temperatures (24{degrees}C, 28{degrees}C, and 32{degrees}C) and determined that there was individual heterogeneity in biting habits (number of bites, timing of bites, etc.). We further explored the consequences of biting heterogeneity using an individual-based model designed to examine whether a particular biting profile determines whether a mosquito is more or less likely to 1) become exposed given a single index case of dengue (DENV) and 2) transmit to a susceptible human individual. Our experimental results indicate that there is heterogeneity among individuals and among temperature treatments. We further show that this results in altered probabilities of transmission of DENV to and from individual mosquitoes based on biting profiles. While current model representation of biting may work under some conditions, it might not uniformly be the best fit for this process. Our data also confirm that biting is a non-monotonic process with temperatures around 28{degrees}C being optimum. Author SummaryMosquito biting is a necessary and critical part of arbovirus transmission. The mosquito must bite once to acquire a virus and again to transmit, and these two bites must be separated by sufficient time for the virus to get to the salivary glands of the mosquito. Thus, both the number and timing of bites is important. We experimentally investigated how these bite characteristics might be different among individuals and further explored how temperature affected the overall heterogeneity of biting in Aedes aegypti mosquitoes, which carry many arboviruses like dengue virus (DENV). We found that the biting profiles - including number and timing thereof - did vary within temperature groups among individuals and compared outcomes associated with each individual in an individual based model of household DENV transmission. Our results further confirmed that temperatures around 28{degrees}C are optimal for mosquito biting (and transmission), that correlations between biting characteristics and transmission were not uniform across temperature, which represents another layer of heterogeneity, and that - at least at 28{degrees}C - the null assumption of an exponential or an exponential like (geometric) distribution of biting in mathematical models of transmission is not the best and offer an alternative.

ecology↗

bioRxiv2019

Age-structured vectorial capacity in a ZIKV-Ae. aegypti model system

The transmission dynamics of arboviruses like Zika virus (ZIKV) are most often evaluated by vector competence and the related extrinsic incubation period (EIP), which represent the proportion of vectors that become infectious given exposure and the time it takes for a vector to become infectious given exposure, respectively. Thus, EIP is the temporality of vector competence, and these measures have been used to evaluate the relative fitness of arbovirus systems. However, another temporal process critical to assessing arbovirus transmission dynamics is the age-structure of vector populations, as studies have demonstrated how vector mortality interplays with vector competence and EIP to alter transmission system efficiency. These and other parameters are critical to vectorial capacity (VC), a measure of transmission potential of a vector-pathogen system. However, how these three components - EIP, vector competence, and age - affect VC still needs to be addressed. We first compared experimentally how vector competence/EIP and mosquito age at the time of infection acquisition (Ageacquisition) interacted in an Aedes aegypti-ZIKV model system. We found that Ageacquisition did not alter the vector competence/EIP using traditional analyses, except in the context of mortality. To capture and quantify this age-dependent context, we developed an age-structured vectorial capacity framework (VCage) by experimentally determining daily mortality and probability of biting, as well as vector competence/EIP parameterized as EIPMin and EIPMax. Like previous studies, we found that arbovirus phenotypes leading to outbreaks are not straightforward and may follow a tortoise and the hare (TotH), whereby slow and steady is as or better than fast and furious phenotypes. Understanding the contributions of these age-dependent life traits as well as VCage allows for quantification and visualization of both the magnitude and temporality of transmission dynamics in an age-dependent manner, which reveals this TotH model that should change how compare and rank arbovirus phenotypes, and perhaps even how we identify highly or negligibly competent vectors.

ecology↗