For this research project, about 305 fresh fertile hen eggs were obtained from Veterinary Research Institute, Lahore. These eggs after cleaning were incubated at 37°C in automatic incubator for 11 days. At the 11th day, candling was done to confirm the fertility of eggs, either they are embryonated or not,. Eggs found dead at the time of candling were discarded. Fertile eggs 305 in number were inoculated with physically and chemically treated mesogenic strain of Newcastle disease virus which had already been treated and stored in plastic vials at -20°C. Each egg was inoculated with about 0.lnil of the treated viral sample. Four eggs were set for each of the factor for each time period. Four eggs were kept control in each factor in which viral suspension without physical or chemical treatment was inoculated.

The project was designed to study the effect of physical and chemical factors on the survival of Newcastle disease virus. The physical factors were temperature, p11 and UV light and chemical factors included five disinfectants like Formaline, Iosan, Phenol Aldekol and Bromosept (QAC). It was noted that at 56°C temperature virus lost its haemagglutinating activity after 45 minutes, but survived this temperature at 15 and 30 minutes exposure. It was observed that virus survived at pH 4 and 9 for 6, 12, 18 and 24 hrs but was killed at pH 1 and 13 for all the said time periods. After exposing virus to UV light, it was examined that Newcastle disease virus survived at UV light exposure for 45 minutes.

As far as the chemical factors were concerned, the results showed that 0.48% concentration of formalin inactivated virus in 30 minutes but not in 15 minutes. Other two concentrations i.e. 0.12% and 0.24% could not inactivate the virus. Phenol and Bromosept showed good antiviral activity against ND virus. 0.4% and 0.6% concentrations of Phenol inactivated the virus within 15 minutes but virus retained its HA activity at 0.2% phenol concentrations for 15, 30 and 45 minutes. The virus survived at 0.1% Bromosept concentration for 45 minutes and at 0.5% concentration for 15 minutes time but its haemagglutinating property was lost at 0.5% concentration in 30 minutes and at 1% concentration, the virus was killed within 15 minutes time. 0.1% concentration of Aldekol could not inactivate the virus in 15, 30 or 45 minutes. At its 0.5% concentration virus was inactivated after 45 minutes exposure but not at 15 and 30 minutes. However 1% Aldekol inactivated virus after 30 minutes but not within 15 minutes time. losan with 0.5% and 1.0% concentrations killed the mesogenic strain of Newcastle disease virus in 15, 30 and 45 minutes respectively. So the results of this study show that losan shows excellent antiviral activity against ND virus and is the best for disinfection of this virus at the farm. Bromosept (QAC) and Phenol should be the other two options for farmers to disinfect their sheds and hatcheries to minimize the chances of infection from Newcastle disease virus.