The Immune Regulation Function Of Allicin On Chicken Inoculated With Reticuloendotheliosis Virus

Reticuloendotheliosis virus(REV) is a member of C type retrovirus, leading to growth retardation, immunosuppressive and runting syndrome in various avian hosts, causing severe damages to the poultry industry worldwide. There is no effective vaccine to REV up to now, so it is in urgent need to find effective methods to prevent or cure reticuloendotheliosis. Allicin is a bioactive substance extracted from garlic. Researchers have found that it has antibacterial, antiviral, and immuno-enhancing activity. It has been widely applied to the fields of medicine and animal husbandry industry is low cost and without drug residue. In this study, we attempted to use allicin to cure REV infected chickens, in hope to lay the foundation for the further research on new drugs for immunosuppressive diseases.This study was aimed to establish a REV infected chicken model, and to explore the regulation function of allicin on reticuloendotheliosis infection damage. Several indicaters were monitored including growth performance and HI antibody titers to NDV and AIV vaccines and so on.The study was divided into two parts. The first part was to establish REV infected chicken model. In order to determine the appropriate time to inoculate REV, the chicken were infected at 3-day-age and 7-day-age respectively. Growth performance, immune organ index, the antibody titers of Newcastle disease virus(NDV) and Avian influenza virus(H5, H9) vaccines were measured; blood routine tests were performed; the ratio of CD4+ and CD8+ lymphocytes were analyzed. The results showed that the growth performance and the antibody titers to NDV and AIV vaccines of both group were significantly inhibited by REV infection(P < 0.05). But the mortality of 3-day-age group was significantly higher than 7-day-age group, with the ratio 52.5%(21/40) and 17.5%(7/40) respectively. Meanwhile, the mortality of control group was the same as 7-day-age group, both were 17.5%(7/40). The results indicated that the infection of REV on SPF chickens lead to severe immunesuppression at both 3 and 7-days-old, but the latter is better age for establishing REV infection chicken model.The second part was to study the regulation function of allicin on REV infected chicken. Five groups were set up: control group, REV infected group(REV), 600 mg/kg allicin in the daily diet after REV infection group(R-600 D group), 300 mg/kg allicin in the daily diet from 1 day old and REV infected on 7 day old group(300D-R-300 D group), 300 mg/kg allicin in daily diet after REV infection group(R-300 D group). Growth performance, immune organ index, the antibody titers of NDV and H9 AIV vaccines were measured at different period after infection; blood routine tests were performed; the ratio of CD4+ and CD8+ lymphocytes were measured. The function of different dosages and feeding time of allicin on the control of REV were compared and obtained the best dosage and feeding time. The results showed that the body weight of R-300 D group began to regain from 5 weeks after infection, significantly higher than REV infected group and R-600 D group(P<0.05). The body weight of 300D-R-300 D group also began to regain weight from 6 weeks after infection, but lower than R-300 D group. The antibody titers of R-300 D group to both NDV and AIV-H9 vaccines were higher than the other groups, close to control group, and there was no difference between 300D-R-300 D group and R-600 D group(P>0.05).The results indicated that the regulation function of allicin on REV infected chicken was related to the feeding dosage and time of allicin. Feeding 300mg/kg allicin after infection remarkably inhibit the decline of growth performance and immune supperssion caused by REV, better the high dosage of 600mg/kg and earlier start feeding time of 1 day old.The results indicated that REV significantly inhibit the growth performance and immune function of SPF chickens, and 7 days old is the better age to inoculate REV. The regulation function of allicin on REV related to the dosage and feeding timing. Feeding 300mg/kg allicin after infection showed the best regulation function on growth performance and immunesuppression. This indicates in a practical application, use excessive dosage or too early would not achieve the best effects and Increase the cost of drug use.