Chicken infectious anaemia virus: An immunosuppressive pathogen of poultry – A review
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Chicken infectious anaemia (CIA) is an emerging disease of poultry, especially of young chicks, causing considerable economic losses to the poultry industry worldwide. The etiological agent, the chicken infectious anaemia virus (CIAV), is the smallest known avian pathogen. CIAV is highly contagious, hardy and ubiquitous and can be vertically transmitted. Circular viral genome (2.3 kb) encodes three distinct viral proteins: VP1, VP2 and VP3. VP1 is the major capsid protein and VP2 is a non-structural scaffold protein. VP1 and VP2 are the protective proteins inducing neutralizing antibodies. VP3 is an apoptin, whose ability to induce tumour-specific apoptosis makes it a promising candidate for gene therapy of various tumours. The disease is characterized by generalized lymphoid atrophy particularly of the thymus, pale bone marrow and liver, anaemia, and severe immunosupression leading to secondary infections. Only a single viral serotype is believed to exist with high sequence identity among different isolates. Tentative diagnosis can usually be made based on flock history, clinical signs, and gross lesions in affected birds. Confirmatory diagnosis needs isolation and identification of the CIAV. Recent DNA detection techniques of PCR, alongwith RE analysis and sequencing have emerged as effective confirmatory tools for studying its molecular epizootiology. Boosting of parenteral immunity is top priority under control measures. Vaccination strategies inclusive of live-attenuated, inactivated and recombinant (r)-DNA vaccines are being explored. The disease has been reported in India, warranting the need for ascertaining epidemiological status of the disease in the country and devise effective control measures timely for this emerging disease.
Chicken infectiois anaemia, chicken infectious anaemia virus, poultry, immunosppression, diagnosis, control.