Submitted to: Avian Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/2007
Publication Date: 2/1/2008
Citation: Pandiri, A.R., Gimeno, I.M., Reed, W.M., Lee, L.F., Fadly, A.M. 2008. Distribution of viral antigen gp85 and provirus in various tissues from commercial meat-type and experimental white leghorn line 0 chickens with different subgroup J avian leukosis virus infection profiles. Avian Pathology. 37:7-13. Interpretive Summary: Avian leukosis virus (ALV) is an economically important virus infection that can cause cancer like disease and other production problems in meat type chickens. Previous observations suggest that infection with ALV at hatch or early in life induce persistent viremia (presence of virus in blood of host for extended periods of time) even in the presence of antibodies against the virus. However, the localization of ALV antigen (viral protein) or its provirus (genetic components) in the tissues of chickens that developed antibodies is not known. Our results demonstrated a direct correlation between viremia and tissue distribution of viral antigen, as expression of antigen was noted in only viremic chickens, regardless of the presence of antibodies against virus. Whereas, using a DNA-based test named polymerase chain reaction (PCR) was useful in demonstrating proviral DNA in majority of the tissues tested from non-viremic, antibody positive chickens. The results suggest that PCR is a more sensitive test than tests for viral antigen in identifying ALV even in chickens that have been exposed to virus, but are not actively viremic. This information should be significant and useful to scientists in academia and industry who are studying the basic principals of virus persistence in ALV infection.
Technical Abstract: Immunohistochemistry (IHC) and polymerase chain reaction (PCR) were used to test for the presence of subgroup J avian leukosis virus (ALV J) envelope antigen gp85 and provirus, respectively in various tissues (adrenal gland, bone marrow, gonad, heart, kidney, liver, lung, pancreas, proventriculus, sciatic nerve, spleen, and thymus). Tissues were collected from 32-week-old commercial meat-type and ADOL experimental white leghorn line 0 chickens with the following different infection profiles: 1) persistently viremic chickens tolerized in ovo with no neutralizing antibody (NAb) on any sampling (tV+A-); 2) persistently viremic, non-tolerized chickens infected at hatch and tested positive for NAb on one or two samplings (ntV+A-); 3) persistently viremic chickens infected at hatch with concurrent NAb on most samplings (V+A+); and 4) non-viremic chickens infected at hatch with detectable NAb response (V-A+). There was a direct correlation between viremia and tissue distribution of gp85, regardless of the NAb status and strain of chickens, as expression of ALV J gp85 was noted in only viremic (tV+A-, ntV+A-, V+A+), but not in non-viremic seroconverted chickens (V-A+). Of the four oligonucleotide primers pairs sets used in PCR to identify ALV J provirus, only one primer set termed H5/H7 was useful in demonstrating ALV J proviral DNA in majority of the tissues tested from non-viremic, antibody positive chickens (V-A+). The results suggest that PCR using primer set termed H5/H7 is more sensitive than IHC in identifying ALV J in chickens that have been exposed to virus, but are not actively viremic.