Response of chickens carrying germline insert ALVA11 to challenge with a field strain of subgroup A avian leukosis virus

The ALVA11 germline insert in chickens is a defective subgroup A avian leuk osis virus (ALV) proviral insert chat expresses a low-to-moderate level of subgroup A ALV envelope glycoprotein. Chicks carrying or lacking ALVA11 wer e evaluated for response to challenge by RPL-42, a pathogenic field strain of subgroup A ALV, by either exposure to chicks shedding RPL-42 or direct i njection with various doses of RPL-42. Chicks carrying ALVA11 were signific antly more resistant, as measured by infectious virus and viral antibody st atus, to horizontal infection and direct injection of RPL-42 than chicks la cking ALVA11.