A subgroup J avian leukosis virus (ALV-J), designated as SD1306, which was isolated and identified from inspection of suspected infection, a Salmonella pullorum (SP) strain was isolated at the same time. Sixty Hy-line brown chickens were used for the study. Detected the body weight, the immune organs index, histopathology, quantity change of the intestinal flora, the viremia and anti-ALV-J antibody after being inoculated the two pathogens. Results showed that the indicators had no significant change during the latent period, while at the 6th and 7th week, compared with other two groups inoculated separately, the body weight of co-infected group was significant lower; the thymus index was below the group infected with SD1306, while the spleen index was significant higher all the time. No evident tumour nodules and swelling in any tissues were seen at necropsy. Histopathological findings revealed large islands of leukomonocytes or myelocytes in tissues containing tumors. Salmonella in rectal feces of co-infected group was much higher than the group infected with Salmonella pullorum from the 3rd week, the number of E. coli significantly exceeded the group infected with Salmonella pullorum at the 7th week. The co-infected group positive rate of ALV-p27 antigen was 69.23%, while the group infected with SD1306 was 38.46% at the 5th week. The positive rate of both groups declined at the 6th week, rose again at the 7th week. Correspondingly the positive rate of anti-ALV-J antibody continued to decrease from the 6th week to the 7th week. It showed that ALV-p27 antigen and antibody level fluctuated strongly in some time and there was a negative correlation between them. The damage to the chicken was more serious in the co-infected chicken than the chicken infected separately.

Key words: Co-infection, Salmonella Pullorum, Subgroup J avian leukosis virus