Potential for contact and mechanical vector transmission of vesicular stomatitis virus New Jersey in pigs

Abstract

Objective - To determine whether swine could be infected with vesicular stomatitis virus New Jersey (VSV-NJ) by routes simulating mechanical vector and contact transmission, and to document clinical response and measure source, duration, and extent of associated viral shedding. Animals - 48 approximately 10-kg male pigs. Procedure - 7 inoculation routes were tested at 3 virus concentrations (106, 104, and 102 median tissue culture-infective doses [TCID50]). Inoculation routes included intradermal (snout), topical application of virus to a scarified area (ear or mucous membrane of the lip), mucosal (oral or conjunctiva) application, and nasal instillation (drop or aerosol). Swine were monitored daily for clinical disease, seroconversion, and virus isolation. Results - Virus was isolated from swab specimens of nasal planum, nasal cavity, saliva, tonsil, and feces from 15 pigs infected by intradermal snout inoculation (106 and 104 TCID50), scarification of the lip (106 and 104 TCID50), and oral route (106 TCID50). Virus was not isolated from plasma. Vesicular lesions were restricted to pigs inoculated via intradermal snout and lip scarification routes. Seroconversion was detected in 23 pigs inoculated by all routes except intranasal aerosol and conjunctival. Frequency of virus isolation from these pigs was dependent on serologic status and presence of vesicular lesions. Conclusions - Viral titers obtained from swab specimens and infective doses indicated that sufficient virus is shed from infected swine for contact or mechanical transmission to occur. Amount of virus is highest when lesions are present and before seroconversion. Pigs may represent an effective large-animal model for studying pathogenesis and transmission of VSV-NJ. (Am J Vet Res 1999;60: 43-48).