Presence of specific antibodies and proviral DNA of small ruminant lentiviruses in lambs in their first weeks of life

The aim of this study was to investigate the presence of proviral DNA and colostral antibodies in lambs born to and fed by ewes infected with small ruminant lentiviruses (SRLV). It was demonstrated that all 20 lambs tested 24 h after colostrum ingestion were serologically positive with high antibody titres. These gradually decreased with time, and at week 12 all lambs were seronegative. Twenty percent of lambs tested at the 2nd week postpartum were provirus positive by qPCR as a result of consumption of infected colostrum or in utero infection. When tested at three months of life, 95% of the lambs were provirus positive, probably as a result of horizontal transmission of the virus. Since these animals could play an important role in the early propagation of SRLV to susceptible herdmates, early removal of provirus-positive animals could help to prevent new infections.