Identical Viral Genetic Sequence Found in Black Flies (Simuliumbivittatum) and the Equine Index Case of the 2006 U.S. Vesicular Stomatitis Outbreak.

Barbara S Drolet,Miranda R Bertram,Will K Reeves,Steven J Pauszek,Luis L Rodriguez,Kristine E Bennett

doi:10.3390/pathogens10080929

Abstract

In 2006, vesicular stomatitis New Jersey virus (VSNJV) caused outbreaks in Wyoming (WY) horses and cattle after overwintering in 2004 and 2005. Within two weeks of the outbreak onset, 12,203 biting flies and 194 grasshoppers were collected near three equine-positive premises in Natrona County, WY. Insects were identified to the species level and tested by RT-qPCR for VSNJV polymerase (L) and phosphoprotein (P) gene RNA. Collected dipterans known to be competent for VSV transmission included Simulium black flies and Culicoides biting midges. VSNJV L and P RNA was detected in two pools of female Simulium bivittatum and subjected to partial genome sequencing. Phylogenetic analysis based on the hypervariable region of the P gene from black flies showed 100% identity to the isolate obtained from the index horse case on the same premises. This is the first report of VSNJV in S. bivittatum in WY and the first field evidence of possible VSV maintenance in black fly populations during an outbreak.

Highlights

Vesicular stomatitis (VS) is a vector-borne, zoonotic disease caused by the RNA virus vesicular stomatitis virus (VSV), a Vesiculovirus in the family Rhabdoviridae, which primarily affects horses, cattle, and swine with clinical signs that include transient fever, excessive salivation, and lesions in the oral cavity, on the lips, nose, coronary bands, and teats of livestock [1,2]
Swabs of lesions and blood samples were obtained by the attending veterinarian and submitted to the U.S Department of Agriculture (USDA), APHIS, National Veterinary Services Laboratories (NVSL; Ames, IA)
vesicular stomatitis New Jersey virus (VSNJV) was confirmed in lesion swabs by virus isolation and VSV antibody was confirmed by cELISA

Summary

Introduction

Vesicular stomatitis (VS) is a vector-borne, zoonotic disease caused by the RNA virus vesicular stomatitis virus (VSV), a Vesiculovirus in the family Rhabdoviridae, which primarily affects horses, cattle, and swine with clinical signs that include transient fever, excessive salivation, and lesions in the oral cavity, on the lips, nose, coronary bands, and teats of livestock [1,2] Because these lesions in cattle and swine resemble those caused by foot and mouth disease virus, VS is designated as a reportable disease resulting in economic losses primarily due to animal quarantines and trade restrictions [3,4]. Previous exposure of horses during a single VS outbreak year resulted in VS-positive horses maintaining antibody titers for 10–12 years [5,6] For these reasons, USDA policy is to only perform VS testing on non-clinical animals if required for export. Confirmed positive and suspect premises are quarantined for at least 14 days from the onset of lesions in the last affected animal on the premises [7]

Methods

Results

Conclusion