Decline of maternal antibodies to small ruminant lentivirus in goat kids

What is it about?

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 SRLVseropositive 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.

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Why is it important?

Caprine arthritis-encephalitis (CAE) is currently one of the main goat health issues worldwide. The disease spreads insidiously in a herd, affecting high proportions of goats before first clinical cases of arthritis and emaciation can be noticed. However, arthritic goats constitute only the tip of the iceberg since gradually progressing infection leads to subclinical losses to the herd mainly by reducing milk and cheese yield, and worsening milk quality. Therefore, CAE diagnostics rely on laboratory tests. Even though detecting small ruminant lentivirus (SRLV) using methods based on molecular biology appears to be a sensible diagnostic approach, no such tests have so far been introduced in routine practice, and serological assays, namely ELISA, remain the mainstay of field CAE diagnostics