Host Predilection and Transmissibility of Vesicular Stomatitis New Jersey Virus Strains18 December 2012
Viral transmission via animal-to-animal contact and insect-vectored transmission are occurred at higher rates when affected animals are presenting severe clinical signs and shedding high concentrations of virus, according to researchers at the University of Georgia investigating transmission of the virus in pigs and cattle.
Epidemiological data collected during epidemics in the western United States combined with limited experimental studies involving swine and cattle suggest that host predilection of epidemic vesicular stomatitis New Jersey virus (VSNJV) strains results in variations in clinical response, extent and duration of virus shedding and transmissibility following infection in different hosts, according to Paul F. Smith and colleagues at the University of Georgia in the US.
In their paper in BMC Veterinary Research recently, they report that laboratory challenge of livestock with heterologous VSNJV strains to investigate potential viral predilections for these hosts has not been thoroughly investigated.
Most vesicular stomatitis viruses have broad host ranges, infecting a large number of vertebrate and insect species, the researchers explain in their paper. In the United States, VSNJV is one of the causative agents of vesicular stomatitis (VS) in domestic livestock. Clinically affected animals typically present with vesicular lesions on the muzzle, tongue, lips or coronary band, and occasionally the teats. Vesicles usually rupture within 24 to 48 hours, leaving reddish ulcerations, which begin healing in six to seven days. Excessive salivation and a loss of appetite can occur when lesions are around the muzzle or in the oral cavity.
Previous work has shown that, in experimental settings, virus transmission can occur by various biologically relevant routes including biological and mechanical insect transmission and animal-to-animal contact.
In separate trials conducted by the Athens-based group, homologous VSNJV strains (NJ82COB and NJ82AZB), and heterologous strains (NJ06WYE and NJOSF [Ossabaw Island, sand fly]) were inoculated into cattle via infected black fly bite. NJ82AZB and NJ06WYE were similarly inoculated into pigs.
Clinical scores among viruses infecting cattle were significantly different and indicated that infection with a homologous virus resulted in more severe clinical presentation and greater extent and duration of viral shedding.
No differences in clinical severity or extent and duration of viral shedding were detected in swine.
Differences in clinical presentation and extent and duration of viral shedding may have direct impacts on viral spread during epidemics, concluded Smith and colleagues. Viral transmission via animal-to-animal contact and insect-vectored transmission are likely to occur at higher rates when affected animals are presenting severe clinical signs and shedding high concentrations of virus.
More virulent viral strains resulting in more severe disease in livestock hosts are expected to spread more rapidly and greater distances during epidemics than those causing mild or no obvious signs, the Georgia researchers added.
Smith P.F., E.W. Howerth, D. Carter, E.W. Gray, R. Noblet, R.D. Berghaus, D.E. Stallknecht and D.G. Mead. 2012. Host predilection and transmissibility of vesicular stomatitis New Jersey virus strains in domestic cattle (Bos taurus) and swine (Sus scrofa). BMC Veterinary Research, 8:183. doi:10.1186/1746-6148-8-183
Further ReadingYou can view the full report (as a provisional PDF) by clicking here.