Efficacy of ultraviolet C exposure for inactivating Senecavirus A on experimentally contaminated surfaces commonly found on swine farms.

The objective of this study was to evaluate the efficacy of ultraviolet C light (UVC) for inactivating Senecavirus A (SVA) on three different experimentally contaminated surfaces commonly found in swine farms. An experimental study under controlled conditions assessed the effect of UVC on an SVA isolate on coupons composed of three surface types: cardboard, cloth, and plastic. Each coupon was inoculated with 2 mL of SVA (107.5 TCID50/mL) and 1 mL of PBS or 1 g of feces on the top or bottom surface of the coupon and allowed to dry (90 min at 25℃). Coupons were exposed to UVC in a commercially available pass-through chamber (PTC) for 5 min or in a simulated supply entry room (SER) for 120 min. After exposure, virus isolation was attempted from each coupon and virus titers were determined in cell culture. The efficacy of UVC was determined by the reduction in virus titer for the UVC treated groups compared to their respective non-treated positive controls. UVC was effective at inactivating SVA on plastic surface free of organic material. The plastic coupons inoculated with SVA and PBS had a significantly lower virus titer (>7-log reduction) in both the PTC and SER when compared to their relative positive controls. All other groups in the PTC and SER had a 2-log reduction or less. The reduction in virus titer on the top and bottom inoculated surfaces, following exposure to UVC, were not statistically different. The data from this study provide some guidance when applying UVC for disinfection in the field.

Equine rhinitis A virus: structural proteins and immune response.

Equine rhinitis A virus (ERAV) is a picornavirus that has been reclassified as a member of the Aphthovirus genus because of its resemblance to foot-and-mouth disease virus at the level of nucleotide sequence and overall genomic structure. The N-terminal amino acid sequence of three of the four capsid proteins of ERAV was determined and showed that the proteolytic cleavage sites within the precursor P1 polypeptide occur exactly as those predicted for an aphthovirus-like 3C protease, which generates the capsid proteins VP1 and VP3. However, the autocatalytic cleavage site between VP4 and VP2, which is independent of 3C protease cleavage, was different from that predicted previously. ERAV.393/76 antisera from horses and rabbits showed different reactivity to the viral structural proteins in both serum neutralization assays and Western blots. High neutralizing antibody titres appeared to correlate with strong reactivity to VP1 in Western blots.

Inactivation of viral agents in bovine serum by gamma irradiation.

Cell culture origin or suckling mouse brain origin viruses of Akabane disease, Aino, bovine ephemeral fever, swine vesicular disease, hog cholera, bluetongue, and minute virus of mice were each suspended in bovine serum. Aliquots (1 mL) were exposed to various doses of gamma radiation from a 60Co source while at -68 degrees C. Aliquots (100-mL) of serum from a steer experimentally infected with foot-and-mouth disease virus were similarly irradiated. The samples were assayed for infectivity in cell culture systems before and after irradiation, and the data points were analyzed by linear regression. The irradiation doses (in megarads) necessary to inactivate one log10 of viral infectivity (D10) was calculated for each virus. D10 is otherwise known as the slope of the regression line. The r2 value, a measure of association with 1.0 = perfect fit, was also calculated for each regression line. The values (D10, r2) for each virus were as follows: Akabane, 0.25, 0.998; Aino, 0.35, 0.997; bovine ephemeral fever, 0.29, 0.961; swine vesicular disease, 0.50, 0.969; foot-and-mouth disease, 0.53, 0.978; hog cholera, 0.55, 0.974; bluetongue, 0.83, 0.958; and minute virus of mice, 1.07, 0.935.

Immunogenicity of equine herpesvirus type 1 (EHV1) and equine rhinovirus type 1 (ERhV1) following inactivation by betapropiolactone (BPL) and ultraviolet (UV) light.

Some kinetic data on the inactivation of equine herpesvirus type 1 (EHV1) and equine rhinovirus type 1 (ERhV1) by betapropiolactone (BPL) and ultraviolet (UV) irradiation are reported. 0.25% BPL at 37 degrees C for 1 h reduced the titre of EHV1 by greater than 10(3 . 4) and of ERhV1 by greater than 10(4 . 1) TCID50/ml. UV irradiation (334 microW/cm2) produced similar reductions in titre after 2 min. These data were used as a basis for inactivating EHV1 and ERhV1 by the combined action of BPL and UV irradiation. Viruses were exposed to 0.1% BPL for 1 h at 4 degrees C with constant stirring, followed by UV irradiation for 2 min, followed by incubation for 3 h at 37 degrees C. Inactivated EHV1 elicited secondary immune responses only in horses whereas ERhV1 produced primary immune responses in mice (including athymic nu/nu mice), rabbits and probably in horses.