ABSTRACT. In the 3 years leading up to November 2009, 6 different types of naturally occurring neoplasms associated with avian leukosis virus subgroup J (ALV-J) were diagnosed by histopathology, polymerase chain reaction (PCR) and immunohistochemistry (IHC) in 140 layer hens out of approximately 100,000. The most prevalent tumor type was hemangioma (50%) in commercial layer flocks; the second most prevalent neoplasm type was myelocytoma (38.6%); a small number of ALV-J positive lymphomas (4.3%) that were not associated with Marek's disease (MD) or lymphoid leukosis (LL) was observed. Histiocytic sarcomas (2.1%) were found mainly in the spleen, liver and kidney. Fibrosarcomas (2.8%) presented as metastatic thigh, liver, lung and kidney neoplasms. Three cases of intestinal adenocarcinoma (2.1%) were found associated with ALV-J. Chickens with multiple tumors were a common phenomenon. Usually, hemangiomas plus myelocytomas (8.6%), myelocytomas plus histiocytic sarcomas (2.1%), hemangioma plus myelocytoma and lymphoma (3.6%) were found in various viscera organs. The present report describes the occurrence of multiple neoplasms associated with ALV-J in field layer hens.KEY WORDS: avian leukosis virus subgroup J (ALV-J), layer chickens, multiple neoplasms.J. Vet. Med. Sci. 72(8): 1027-1033, 2010 Avian leukosis virus subgroup J (ALV-J), first described in the United Kingdom in 1991 and later in other countries, has been associated primarily with myeloid leukosis in meat-type chickens [8,[11][12][13][14][15]. ALV-J has caused severe economic losses in broiler breeders throughout the world. Vertical transmission from broiler breeders to progeny is more frequent with ALV-J than with other ALV subgroups [25].ALV-J in the field has occurred almost entirely in meattype chickens several years ago. Layers have rarely become infected, but experimental studies with Rous sarcoma virus having the inserted envelope gene of ALV-J by Payne [16] have shown that both layers and turkeys are susceptible to ALV-J infection, while other poultry and game birds appear to be resistant.The frequencies of different tumor types seen by Payne [11] during 1996-1998 from suspect ALV-J infected flocks were 58% for myeloid leukosis (ML), 12% for histiocytic sarcoma (HS), 9% for erythroblastosis and 5% for blast cell tumors. Numerous birds had more than one type of tumor, and some had up to four different types.In chickens, layer strains are considered to be at risk in China and their exposure to ALV-J contamination has already been demonstrated by Xu [23,24,26] and Cheng [6]. ALV-J in egg-type chickens with ML has already resulted in significant economic losses in China. Gingerich [9] also reported that a recombinant ALV containing the long terminal repeat (LTR) of the subgroup J and the envelope of subgroup B was isolated from commercial White Leghorn flocks with ML. Cheng [5] reported cases of ML diagnosed in a local Chinese breed that is commonly recognized as a dual purpose type of chicken, both for eggs and meat, in Shandong Province, P.R. China....

The critical time of avian leukosis virus subgroup J (ALV-J)-mediated immunosuppression was determined by body weight, relative immune organ weight, histopathology, and presence of group specific antigen and antibodies in specific pathogen-free (SPF) chickens. CD4+ and CD8+ cell activity in the spleen, total and differential leukocyte counts in blood, and viral RNA levels in spleen were measured. Significant growth suppression was observed in the two ALV-J-infected groups. A strong immune response by infected groups was present in spleen at 2-weeks-of-age, but after 4-weeks-of-age, the response decreased quickly. The thymus and bursa showed persistent immunosuppression until 4-weeks-of-age. Proliferation of fibroblasts and dendritic cells were observed in immune organs at 4- and 5-weeks-of-age. However, the granulocyte cell number was markedly lower in the infected groups than in the control group. In group 1 (day 1 infection) CD4+ cells increased during the second week but significantly decreased during the fourth week, while group 2 (day 7 infection) showed the opposite effect. Viral RNA increased significantly by the fourth week. These data identify 3~4 weeks post-infection as the key time at which the ALV-J virus exerts its immunosuppressive effects on the host.

An enzyme-linked immunosorbent assays (ELISA) based on recombinant nucleocapsid (N) protein generated in Escherichia coli was evaluated for its sensitivity and specificity for diagnosis of porcine epidemic diarrhea (PEDV) infection. The N gene encoding the N protein was cloned and expressed as a fusion protein with His tag protein in E. coli. The recombinant N protein was migrated at 48 kDa and reacted with six histidine tag specific monoclonal antibody by immunoblotting. Recombinant N protein ELISA (rnELISA) demonstrated 98.7% specificities among (80) PEDV-free individuals, and 98% sensitivity ranging among (103) clinical samples with PEDV. On testing 884 field samples, an overall agreement of 88.3% was generated between the SN and rnELISA. Taken together, these results indicated that nucleocapsid protein may be a useful antigen for the sera-diagnosis of PEDV and it was also suggested that the ELISA is a highly sensitive and specific test for detecting antibodies to PEDV.

In this report, for surface display of viral antigen on lactobacilli, we have developed a surface antigen display system using the poly-gamma-glutamate synthetase A protein (pgsA) of Bacillus subtilis as an anchoring matrix. Recombinant fusion proteins comprised of pgsA and neucleocapsid protein of PEDV were stably expressed in Lactobacillus casei. Surface location of fusion protein was verified by ELISA, immunofluoresence microscopy. Oral and intranasal inoculations of recombinant L. casei into pregnant sow and mice resulted in high levels of serum immunoglobuline G (IgG) and mucosal IgA, as demonstrated by rnELISA(recombinant N protein ELISA) using recombinant N protein. Absorbance of IgG in pregnant sow sera highly increased duration of the experiment. More importantly, the level of IgA in colostrum were increased significantly higher than that of IgG. The IgG levels of the piglets were increased after suckling colostrum secreted from sows previously inoculated recombinant L. casei. These results indicate that mucosal immunization with recombinant L. casei expressing PEDV N protein (neucleoprotein of PEDV) on its surface elicited high levels of mucosal IgA and circulation IgG immune responses against the antigen N of PEDV.