Immunomodulatory effect of muramyldipeptide, poly I:C and L-arginine on humoral immune response in broiler chicks inoculated with betapropiolactone inactivated inclusion body hepatitis vaccine¹

Immunomodulatory effect of muramyldipeptide (MDP), Poly I:C and L-arginine in 10-day old broiler chicks vaccinated with BPL-inactivated IBH (FAV-4) vaccine was studied. The vaccine was prepared with the virus grown in chicken embryo liver cells monolayers. Chicks were immunized in a vaccine dose of 0.25 ml each by intramuscular route. On 3^rd and 7^th days of vaccination, L-arginine (100 mg/bird), Poly I:C (50 mg/bird) and MDP (100 mg/bird) were administrated separately in three groups of vaccinated chicks. The inoculated chicks were challenged each with 10^4.37 LD₅₀ of virulent FAV-4 virus in a dose of 0.2 ml at 21^st day of vaccination. Humoral immune response was studied by measuring the antibody levels by ELISA at various days of interval after vaccination and challenge infection. MDP treated as well as L-arginine treated group of chicks showed significant higher antibody response on 21^st day post vaccination, however the response of MDP treated group of birds was slightly higher than L-arginine group. As compared to the MDP and L-arginine, poly I:C showed lower immunostimulatory effect for humoral immune response. On 10^th day of challenge infection, the protection of 70, 100, 80 and 90% were recorded in group of chicks inoculated with BPL-inactivated IBH virus, BPL-inactivated IBH virus + MDP, BPL-inactivated IBH virus + poly I:C and BPL-inactivated IBH virus + L-arginine, respectively.