Meeting Abstract
Alphaviruses are positive sense RNA viruses carried by arthropods that are responsible for a number of encephalitic and rheumatic diseases in vertebrates. Buggy Creek Virus (BCRV) is an alphavirus that is transmitted to birds by the cimicid swallow bug (Oeciacus vicarius) via infestation of the birds’ nests. It is hypothesized that in times of high stress (such as in overwintering bugs), BCRV produces incomplete particles called defective interfering (DI) particles that prevent assembly of the full wild type phenotype. We located five active cliff swallow colonies with swallow bugs and tested swallow bugs for the presence of BCRV over time and in different age classes of swallow bugs. Upon collection, bugs were sorted into five age groups, homogenized and frozen for downstream testing of viral presence and cytopathic effect. Viral RNA was detected through RT-PCR, and viral infectivity was measured using a modified TCID50 procedure. Over the course of three months, we saw a positive correlation between cliff swallow nesting activity and swallow bug populations, as well as detectable BCRV. Specifically, detectable BCRV decreased 52% in bug pools after cliff swallows left our sites. The results of this project indicate that BCRV persistence in swallow bugs is highly dependent on the presence of cliff swallows, with peak BCRV RNA being detected during the nesting season. Although high levels of BCRV RNA were detected across multiple swallow bug age classes and sites, BCRV isolated from bugs at all time points was only minimally cytopathic. Future work is needed to determine the genomic structure of BCRV isolates from swallow bugs and to confirm possible involvement of DI particles in the viral dynamic patterns detected in this project.
