Enhancing the immunogenicity and protective efficacy of inactivated pigeon paramyxovirus vaccine (PMV-1) using synthetic polymeric adjuvant

Abstract

Pigeon paramyxovirus type 1 (PPMV-1) is a serious pathogen facing the pigeon industry. Thus, this study aimed to preparation and evaluation of two inactivated vaccines using Carbopol and Aluminum hydroxide-based adjuvants to control such a problem.  A total of 45- four weeks old, apparently healthy pigeons were allocated into 3 groups (15 birds each) as follow: group 1 (G1) received 0.5 ml, S/C Carbopol adjuvanted vaccine, group 2 (G2), received 0.5 ml S/C of aluminum hydroxide-based vaccine, group 3 (G3) received 0.5 ml S/C sterile saline and kept as control group. Five serum samples were obtained from each bird weekly post vaccination to measure anti-PPMV-1 antibodies using HI test. At 35 days post immunization, all vaccinated pigeons were challenged with 20µl containing 10⁶ EID50/bird of PPMV-1 YA/14 strain by eye drop route, all pigeons were kept under observation for 10 days during the observation period any clinical signs or moralities were recorded also, cloacal swabs were collected 4-, 7- and 10-days post challenge to measure the shedding level. The potency test revealed that the prepared inactivated vaccine (PPMV-1) with synthetic polymeric adjuvants were potent and efficient. By studying the elicited serum antibody dynamics in vaccinated pigeon using HI test showed that antibody, the beak antibody titer reached by the 4^th week post immunization (6 and 5 log 2) for both G1 and G2 respectively (but G1 is significantly increase than G2) and continued to the 5th week where it reaches 6.5 and 5.6 log2 for both groups in order. (G1 is significantly increase than G2), which indicated that the PPMV-1 inactivated vaccine in both G1 and G2, results in systemic adjuvant activity, including a long-lasting protective immune response after a single dose administration without any adverse reaction. G1 and G2 showed the lowest shedding level that was zero at the 10^th day post challenge and the overall reduction level of both vaccinated groups was 4.9 and 4.5 for both G1 and G2, respectively. However, the prepared inactivated PPMV-1 Carbopol based vaccine is safe and could significantly poses the immune response more effectively than the aluminum hydroxide-based vaccine.