H Haghbinnazarpak - Department of Clinical Sciences, Faculty of Veterinary Medicine, Islamic Azad University, Garmsar Branch, Iran۲
S Fariaby - Department of Clinical Sciences, Faculty of Veterinary Medicine, Islamic Azad University, Garmsar Branch, Iran
A Qarehkhanishirejini - Graduate of Veterinary Sciences, Faculty of Veterinary Medicine, GarmsarBranch, Islamic Azad University, Garmsar, Iran
R Marandizi - Graduate of Veterinary Sciences, Faculty of Veterinary Medicine, GarmsarBranch, Islamic Azad University, Garmsar, Iran

Introduction and objectives:Avian influenza virus (AIV) is a member of Orthomyxoviridae type A that can cause avian infectious diseases.AIV has various subtypes, out of which H9N2 AIV was first isolated from chickens in southern China in 1994. Subsequently, AIV rapidly spread in China and has become the most prevalent pathogen in poultry. H9N2 AIV, as one of the low pathogenic avian influenza viruses (LPAIVs), causes immunosuppression in birds and is prone to induce secondary infection, decrease egg production, and cause respiratory symptoms.The purpose of the HI test is to get information from the titer obtained from vaccination against the flu virus to get an understanding of the correct vaccination during the breeding period.Materials and Methods: In this research, blood sampling was carried out in the laying hens in GarmsarCounty.Blood collection from produced laying flocks with at least 2 rounds of vaccine was killed and no history of conflict.30 samples were taken from the laying farms, Samples were sent to the relevant laboratory and the HI duplicateinfluenza test was performed.Conclusion:Titers from vaccination of laying hens with at least two vaccinations from titer 6.3 to 8.3 varied.Due to the fact that the influenza pathogen is strong, the herds should be better vaccinated.So that less damage can occur in the event of a conflict.

Influenza, HI, Laying hens, Vaccine, Garmsar