Evaluation of endemic and epidemic strains of vesicular stomatitis virus infection in Culicoides sonorensis midges

Authors: ROZO-LOPEZ, PAULA - Kansas State University; Pauszek, Steven; Rodriguez, Luis; LONDONO, BERLIN - Kansas State University; Drolet, Barbara

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/31/2021
Publication Date: N/A
Citation: N/A

Interpretive Summary: Interpretive Summary not required in accordance with ARS-115 Publications P & P 152.1 v.5 (10/19/2019)chapter 5 page 31 Matrix for Data Entry Determinations. Kmm

Technical Abstract: Vesicular stomatitis (VS) is a viral disease primarily affecting cattle, horses, and swine. Endemic to Central and South America, VS outbreaks in the US occur sporadically every five to ten years, lasting for a single year (incursion year) and often re-emerging for a second year (expansion year). Virus spreads from animal-to-animal by direct contact but is also vector-borne. During outbreaks, especially in expansion years, Culicoides biting midge vectors likely play a key role in inter-herd viral spread. Earlier phylogeograhic studies showed that in 2012, a VS virus (VSV) (epidemic strain) successfully spread northward out of an endemic area in southern Mexico and into the US, causing disease in horses in New Mexico and Colorado. In contrast, a genetically related strain from the same area in southern Mexico (endemic strain), did not move out of the endemic zone and into the US. It is not clear why some viral lineages escape the endemic areas and move northward into the US, and some do not. Whole-genome sequencing revealed the two strains differed in seven significant amino acid changes. Comparative infection studies in pigs showed that the epidemic strain was more virulent than the endemic strain, possibly contributing to its overall ability to escape the endemic area and spread northward into the US. Here, we evaluated the efficiency of these two viral strains to infect Culicoides biting midges and to disseminate to the salivary glands for subsequent bite transmission. Our results showed that the epidemic strain had a significantly higher infection rate and a higher dissemination rate in midges, compared to the endemic strain. Thus, in addition to affecting virulence, small genetic changes also affect virus-vector interactions, which may contribute to the ability of a specific viral lineage to move out of an endemic area in Mexico and into the US.