Pathogenicity Of ALV Strains With The Acute Or Chronic Tumorigenicity To Difterent Species Of Chickens

Avian leukosis virus (ALV) designates a variety of transmissible benign and malignantneoplasms of chickens caused by members that belong to the family Retroviridae. It can causechickens’ subclinical infection and production performance decrease. ALV-J that mainlycauses myeloid tumors has the strongest infectivity and pathogenicity. The culled rate of badlyinfected chickens can reach20%. In recent years, ALV-J is not only prevalent among whitemeat-type broilers, but also widely spread to variety chickens in the different places of China.However, ALV-J infection in flocks of different origins is still unclear at present. Further more,the comparison study on ALV-J susceptibility in local chicken lines in China is insufficientgreatly.The comparison study on pathogenicity of six chicken lines of different origin wasconducted using two ALV-J strains from layer-chicken and “817” broiler hybrids. The resultindicated that ALV-J was identified from strain SD1005from “817” broiler hybrids, whichhad the characteristic of acute and high tumorigenicity. The study demonstrated that ALV-Jstrain PY081023from layer-chicken and mixed strain SD1005of ALV-J and ALV-A from“817” broiler hybrids are highly related to the varieties of breeds of animals.1Pathogenicity of strain SD1005from the acute tumorigenicity of “817”broiler hybrids1.1Co-infection of different subgroup ALV in strain SD1005The ALV strain SD1005was obtained from the jugular soft tissue sarcomas of36-d“817” broiler hybrids in some place of Shandong. The tissue and cell lysis solution wasprepared and inoculated in “817” Broiler Hybrids and SPF chickens for regression test, thenthe duplicate soft tissue sarcomas were obtained. The duplicate soft tissue sarcomas of “817”Broiler Hybrids were prepared to culture and touch the piece, and then ALV-A and ALV-Jwere identified by IFA. In the meantime, ALV-A and ALV-J were discovered co-infection inthe same cell. The Biopsy specimen slides from different organs of chickens with tumors wereused for pathological observation and ALV-J determination by methods ofimmunohistochemistry (IHC) method and indirect immunofluorescence fluorescence (IFA), respectively. The result showed that ALV-J was detected from bursa of fabricius, marrow,liver, heart, spleen and tumor by both dyeing methods. Meanwhile, ALV-A and ALV-J wereidentificated with two pairs of primers toward ALV-A and ALV-J by PCR respectively.1.2Comparison study of the pantropic trends of acute sarcoma virus strain SD1005Strain SD1005from “817” broiler hybrids is a co-infection strain, ALV-A and ALV-Jhave been isolated from it. After experiment on tumorigenicity and inoculation site infectionfor one-day-old “817” broiler hybrids, the tumor was replicated in relevant inoculation sitesuch as neck, chest, and abdomen, which means that the generation of tumor is highlyrelevant to the site of inoculation. Age of the “817” broiler hybrids appeared to be animportant factor in tumorigenesis. Test “817” broiler hybrids of1d,7d,14d and21d hadtumor occurrence rate at100%(20/20),94%(16/17),100%(7/7) and37%(7/19),respectively. Obviously, tumor occurrence rate is closely related to chicken infection age.Artificial infection of one-day-old hybrid broilers (hybrid817), Hailan Grown layers,White-Feathered broilers and White-Feathered Laihang SPF breed chicks induced tumor inthe first three test animals14d later, and tumor occurrence rate was more than80%5w later.But the tumor could be seen for the dead chicken of White-Feathered Laihang SPF21d later,and36d later, the tumor occurrence rate was only24%(11/45). The study demonstrated thattumor occurrence is highly related to the varieties of breeds of animals. The present resultsindicated that there was mixed viruses in the soft tissue sarcomas from “817” broiler hybrids,with acute and high tumorigenicity.2Pathogenicity of strain PY081023from Nike chicken to different speciesof chickensTo compare the pathogenicity differentiation of ALV-J strain PY081023from Nikechicken for different variety chickens,2000TCID50per chicken was used to do artificialinfection in30one-day-old Nike and30Laiwu Black chickens, respectively. The resultindicated that ALV-J infection in Laiwu Black chicken resulted in growth slowly of chickens,and had a significant difference with comparison group (p<0.05), while there was nosignificant difference in the parameters of humoral immunity (p>0.05). There was nosignificant difference between infected group and comparison group in Nike chickens(p>0.05). Parameters of spleen CD4+, CD8+T cells subset were measured in6w and7wartificial infection chickens. The result showed that the parameters of spleen CD8+T cells subset of infected group were lower than that of comparison group in both Nike and LaiwuBlack chickens (p<0.05), CD4+T cells of7w Nike infected group were significant higher thanthat of comparison group, and CD4+T cells of6w and7w Laiwu Black infected group werelower than that of comparison. The test result indicated that PY081023strain from Nikechicken had pathogenicity differentiation for these two varieties of chickens. The same doseof ALV-J infection for Laiwu Black chicken had a stronger pathogenicity than Nike chickens.