Molecular Characterization of Chicken Infectious Anemia Virus Isolated From Commercial Poultry with Respiratory Disease Complex in India

摘要

Chicken infectious anemia (CIA) is a highly contagious disease of young chicken, characterized by severe anemia, generalized lymphoid atrophy and increased mortality. The causative agent of the disease is Chicken Anaemia Virus (CAV), belonging to the genus Gyrovirus of the family Circoviridae. CAV has been included in the list of emerging and important viruses that are a severe threat to the Indian poultry industry. Although a few sequences of CAV from India are available in GenBank, no systematic analysis of Indian CAV strains has been performed to the best of our knowledge. Thirty–two commercial poultry flocks with a history of respiratory disease complex (RDC) from four different states of India were included in this study. Necropsy was carried out on freshly dead and ailing birds. Tissue samples were collected aseptically for direct tissue PCR detection of CAV. The PCR products were further subjected to sequencing to study the molecular epidemiology. PCR amplification of VP2 gene from the clinical tissues yielded expected product size of 419 bp in 30 out of 32 clinical cases screened. The Indian CAV viruses grouped with the major branch that consists of viruses from China, Brazil, USA, Malaysia, Bangladesh and Australia. The 16 Indian isolates shared 98.8 – 100 % homology among them. The percent identity matrix calculated for Indian isolates with CAV isolates from various parts of the world indicated closest relationship with isolates from China, USA and Australia (98.5–99.7 %), whereas Brazil, Malaysia and Bangladesh shared (98.8–100%) homology with Indian isolates. Further epidemiological and molecular studies are suggested to know the magnitude of infection and design appropriate disease prevention and control strategies for this economically important pathogen of poultry.