Decline of maternal antibodies to small ruminant lentivirus in goat kids

We carried out this study to determine for how long small ruminant lentivirus (SRLV)‐specific antibodies can be detected by three commercial ELISA kits in goat kids after suckling infected does in field conditions. Forty‐one kids born to SRLV‐seropositive asymptomatic does were blood sampled prior to colostrum consumption, and then weekly for 6 months in total. The sera were screened with three commercial ELISA kits: whole‐virus ELISA (wELISA), recombinant transmembrane and capsid antigen ELISA (TM/CA‐ELISA), and surface antigen ELISA (SU‐ELISA). All but one kid were seronegative in all three ELISAs right after birth. At the age of 1 week all kids turned seropositive in wELISA, 39 kids (95%) in TM/CA‐ELISA, and 35 kids (85%) in SU‐ELISA. All seropositive kids turned seronegative in wELISA by the 15th week, and in SU‐ELISA by the 19th week (median of 8 weeks in both ELISA), whereas in TM/CA‐ELISA five kids (13% of 39 initially seropositive) were still seropositive at the age of 6 months (median of 11 weeks). Antibody levels at the age of 1 week proved significantly linked to the duration of maternal antibodies in all three ELISAs and could be employed to predict for how long maternal antibodies would remain detectable.