MATERNAL FACTORS ASSOCIATED WITH PRENATAL TRANSMISSION OF OVINE LENTIVIRUS

Prenatal transmission of ovine lentivirus (OvLV) was studied in 85 ewes and their offspring. The animals were from a flock with endemic OvLV infection and 49 (58%) had serum antibodies to OvLV. Blood was collected from all lambs before they nursed. Using the polymerase chain reaction (PCR), OvLV DNA was detected in peripheral blood mononuclear cells of 13 (11%) of 117 lambs, including two sets of twins. Mothers with OvLV-infected lambs (n = 11) were younger (mean, 2.5 years) and had fewer pregnancies (mean, 2.4) than seropositive ewes (3.2 years and 3.2 pregnancies; P < .05). Of mothers with OvLV-positive lambs, 4 had plasma antigenemia (mean, 31.3 +/- 2.1 ng/mL OvLV) in conjunction with indeterminate antiviral antibody responses by immunoblotting. These results suggest that maternal factors (age and parity) and host-virus interactions (antiviral antibody and antigenemia) are important risk factors in prenatal transmission of OvLV.