Optimization of incubation temperature in embryonated chicken eggs inoculated with H۹N۲ vaccinal subtype of avian influenza virus

There are little information about growth properties of low pathogenic (LP) avian influenza virus (AIV) in embryonated chicken eggs (ECEs) at different incubation temperatures. Knowledge of this information increases the quantity and quality of antigen in vaccine production process. For this purpose, ۱۰-۵ dilution of AIV (A/Chicken/Iran/۹۹/H۹N۲) was inoculated (Intra-allantoic) into ۴۰۰, ۱۱-day old specific pathogen free (SPF) ECEs in the ۰.۱ mL per ECE rate and incubated in ۳۲, ۳۳, ۳۴, ۳۵, ۳۶, ۳۷.۵, ۳۸, ۳۹ ˚C for ۷۲ hr in ۶۵% humidity. Early death embryos in first ۲۴ hr were removed. Amnio-allantoic fluid was withdrawn into the measuring cylinder, and tested for hemagglutination (HA) activity and egg infective dose ۵۰ (EID۵۰). The utilizable ECEs and amnio-allantoic fluid volume was significantly increased in ۳۵ ˚C, (p < ۰.۰۵). Significant difference in HA and EID۵۰ titers, were seen only in ۳۹ ˚C group. Therefore, ۳۵°C is an optimum temperature for incubation of inoculated ECEs.