Immunomodulatory Functions Of Taishan Pinus Massoniana Pollen Polysaccharide On Immunosuppressed Chickens Infected With ALV-J By Different Inoculation

Poultry immunosuppressive disease is one of the major diseases that can not be ignored in the poultry industry,its infectious factors cause vaccination failure,secondary infection and mixed infection of pathogens via infestation of poultry immune system,immune organs,immune cells,and bring huge economic losses to the poultry industry.Immunosuppressive diseases hold a huge potential harm because of its subclinical infection and easily misdiagnosed immunosuppression,and bring severe situations and great challenges for the prevention and control of diseases.Avian leukosis is a neoplastic-immunosuppressive disease caused by the viral infections of avian leukosis virus?ALV?and avian sarcoma virus?ASV?.Subgroup J avian leucosis virus?ALV-J?is a new subtype with stronger pathogenicity and infectivity,which can induce flocks death,multiple tumors,subclinical infection and immunosuppression can not be underestimated.ALV-J has faster and stronger horizontal transmission ability than other exogenous subpopulations.Chicken shelling period is an important period of horizontal transmission to ALV-J,and different inoculation and contact infection can aggravate spread.Moreover,the immunosuppression of chicks induced by different inoculation routes urgently needs to be explored.Taishan pinus massoniana pollen polysaccharide?TPPPS?has obvious immunopotentiating and antiviral activity,and the administration of injection can effectively alleviate the pathogenicity of infection by ALV-B.However,injection administration will not only cause stress to the body but also is not conducive to the production and application.At present,the effect of oral administration of TPPPS and its regulation on the early infection of ALV-J need to be explored.In view of the above research background,in this study,we first artificially established an ALV-J-infected SPF chicken model with different routes of inoculation to analyze the differences of immune suppression caused by ALV-J infection,thereby to evaluate the infection and pathogenicity under different ALV-J horizontal transmission,and to provide scientific evidences for the control and eradication of ALV-J.One-day-old SPF chickens were inoculated with ALV-J via oral,ophthalmic,intraperitoneal,intramuscular infection,then the growth performance,viral loads,and viral shedding of each group were monitored,and the dynamic changes of viremia,antibody secretion and immunological parameters were also determined.The results showed obvious differences in growth and immune performance between different groups.In intraperitoneal and intramuscular infection groups,viremia and virus shedding in cloaca swabs were positive from the 2nd week after inoculation,and this situation existed continuously.Moreover,the weight,immune organ index,lymphocyte transformation rate,CD⁴⁺ and CD⁸⁺T lymphocytes,cytokines?IL-2,IL-4,IFN-??secretion in both intraperitoneal and intramuscular infection groups were significantly lower than the control group,and the antibody conversion were negative.However,the degree of immunosuppression in oral and ophthalmic infection groups was not significant compared with those in the control group.The results indicated that ALV-J infection on 1-day-old chickens is prone to induce immune suppression,in which intraperitoneal and intramuscular infection cause a strongest consequence on viremia and viral shedding,and immunosuppression.This study clarifies the relationship between different ALV-J horizontal transmission and infection,pathogenicity to provide scientific evidences for the study of mechanisms of ALV-J-infection,control and eradication of ALV-J.What's more,to explore the immunomodulation of TPPPS on immunosuppressed chickens infected with ALV-J by different inoculation,one-day-old chickens were inoculated with ALV-J via oral,ophthalmic,intraperitoneal,intramuscular infection similar to horizontal transmission.Simultaneously,orally successive TPPPS administration for 10 days,then the body weight,immune organ index,the dynamic changes of viremia,and viral shedding,antibody secretion and immunological parameters were monitored.The results showed TPPPS delivery can substantially relieve the impaired immunity compared with inoculation group,as characterized by increase in body weight and immune organ index,decline in viremia and viral shedding,antibody secretion in advance and enhance,also increase in lymphocyte transformation rate,CD⁴⁺ and CD⁸⁺T lymphocytes,cytokines?IL-2,IFN-??secretion.Wherein,TPPPS behaved more significant immunomodulation on intraperitoneal and intramuscular infection group.However,the mock group also received effective changes via TPPPS.These results indicated TPPPS had immune enhancement to healthy chickens,it also behaved remarkably immunomodulation on immunosuppressed chickens infected with ALV-J by different inoculation.Thus,TPPPS can be used as an immunoenhancer to reducethe immune suppression and economic losses for ALV-J prevention and control in early infection.