Preparation and evaluation of multivalent infectious bronchitis vaccine from commercial vaccine strains

Abstract

This study was designed to prepare and evaluate multivalent live attenuated (IBV) vaccine (lyophilized seed) from the commercial IBH120, 4\91 and MA5 strains in ALkindy Company for Drug and Vaccines Production, to reduce economic losses and increase the broad protection against infectious bronchitis disease in chickens. The viruses inoculated via chorioallantoic cavity route with 0.1 ml at 9-11 days embryonated eggs obtained from unvaccinated layers against IBV and were passaged for several times, then three equal doses of the strains were mixed, and the embryonated eggs were inoculated with 0.1 ml of the mixed vaccine. After 72 hours the allantoic fluids (Vaccine) were collected. The results of the infective dose of the new vaccine were 103.2 EID50 /Bird. This multivalent live attenuated IB vaccine was tested for (safety, purity, potency, and sterility test) according to the international protocol steps of vaccine production. Efficacy of multivalent vaccine was evaluated (depending on ELISA, HI, and challenge test) by using 160 one day old (Ross 308) chicks divided into four equal groups (40 chicks of each group) reared in well-isolated places. Group (A) was vaccinated with three doses (0.3 ml) of multivalent live attenuated IB vaccine, group (B) was vaccinated with two doses (0.2 ml), group (C) was vaccinated with one dose (0.1 ml) of the multivalent live attenuated IB vaccine via ocular route at the 8th day of age, and group (D) was left without vaccination as a control group. Blood was collected at (1, 8, 14, 21, 28, 35, 42) days for ELISA test. The mean titer of maternal immunity at day one of age was 4849.8±1161.8, decreased to 69.9±35.92 at the 8th day of age before vaccination. The serum of control group was seen avuncular from IB antibodies at the 14th day of age. The experiment showed significant differences (p<0.05) titers resulting from the use of different doses (0.3 ml, 0.2 ml, and 0.1 ml) at age of 14 days, it was 255.30±15.00, 736.60±94.00 and 545.50±17.00 respectively in comparison with zero in control group. The challenge test carried out for different groups with (IB- field isolated Variant 2 strain 105 EID50 / bird which was supplied from Veterinary Directorate) at 28 days old with 0.5 ml through ocular route. Ten birds from each group were taken randomly. According to the clinical signs, morbidity and mortality rate, gross lesion, and the antibody titer, the results carried out that protection rate in group B was higher than others groups, then group C and group A respectively, the test revealed significant differences (p<0.05) between the vaccinated groups, and also between vaccinated groups and the control group. This study has concluded the possibility of production IB multivalent live attenuated vaccine (broad protection vaccine) using different IB Vaccine strains in chickens.