After 5 days of contact challenge, the vaccinated and non-vaccinated animals were separated from the donors. These animals
were rehoused with their original groups ( Fig. 1). Clinical signs and rectal temperatures were monitored for 15 days post challenge. Experiments were conducted in a bio-secure animal isolation unit at IIL. Clotted blood for serology to detect antibodies to both structural and non-structural proteins was collected from in-contact vaccinated and non-vaccinated SCH727965 clinical trial cattle and buffalo on 0, 7, 14, 21 and 28 days post-vaccination and on 9, 14, 19, 25, 32 and 39 days post exposure. The sera were separated, inactivated at 56 °C for 30 min and stored at −20 °C until further use. Titres of neutralising antibodies against FMDV O/IND/R2/75 virus were measured by micro-neutralization assay as described in the OIE Manual of Diagnostic Tests and vaccines . Antibodies to FMDV NSP 3ABC were tested using PrioCHECK® FMDV NS kit (Prionics Lelystad B.V., The Netherlands) . A linear mixed model was used to compare neutralising antibody titres, with log10 titre
as the response variable and time post challenge (as a factor), species and vaccination status as fixed effects and animal as a random effect. Model selection proceeded by stepwise deletion of Antiinfection Compound Library price non-significant terms (as judged by the Akaike information criterion (AIC)) starting from a model including time post challenge, species and vaccination status together with pairwise interactions between each variable. Similarly, a linear mixed model was used to compare NSP antibody responses, with percentage inhibition as the response variable and time post challenge (as a factor), species and vaccination status as fixed effects and animal as a random
effect. Model selection proceeded Oxalosuccinic acid by stepwise deletion of non-significant terms (as judged by the AIC) starting from a model including time post challenge, species and vaccination status together with an interaction between species and vaccination status. Correlation between pre-challenge serum neutralising antibody titres (i.e. those on day 0 post challenge) and post-challenge NSP antibody responses (on day 32 and 39 days post challenge) were assessed for vaccinated buffalo and cattle using Spearman’s rank correlation coefficient. Correlations between serum neutralising antibody titres and NSP antibody responses at each time point, post challenge, were also examined using Spearman’s rank correlation coefficient for unvaccinated and vaccinated cattle and buffalo. All statistical analyses were implemented in R . All twelve of the needle challenged donor buffalo showed tongue and foot lesions as expected. All the vaccinated cattle (6/6) and four vaccinated buffalo (4/6) were protected from clinical disease after 5 days direct contact challenge with these clinically infected donor buffalo. This difference in protection (6/6 in cattle vs 4/6 in buffalo) is not statistically significant (Fisher exact test: P = 0.45).