Chicken anemia virus infection of poultry and its control by vaccines

Chicken anemia virus (CAV) is a non enveloped virus with icosahedral symmetry. It is one of the smallest viruses having diameter of 25 nm that encloses a single stranded circular negative DNA of 2.3 kb size. CAV has been identified as the causative agent of chicken infectious anemia. Chicken infectious anemia disease is also known by name of Blue wing disease, anemia dermatitis syndrome and hemorrhagic aplastic anemia syndrome based on clinical and histopathological lesions. Clinical signs such as anorexia, weakness, stunting growth, unthriftiness, petechiation, ecchymoses, weight loss, anemia can be observed externally in chicks less than 2 weeks of age. However, adult chickens can also gets infected with the virus, though with subclinical symptoms after the maternal antibodies wane. Age related resistance against the disease starts to develop at about 1 week of age and usually gets completed by 2 weeks of age but resistance to infection never develops. Further, CAV once introduced into the flock is considered as a tough virus to deal with because of its resistance to many commonly used disinfectants and its sub-clinical nature in adults and also it is economically devastating to the poultry farmers and hence letting it not into the flock is the only solution. This can easily be achieved by developing highly efficient vaccine against CAV. In view of all the parameters discussed above in this review article we are going to discuss about different types of strategies employed by different research groups for development of high efficacy vaccines against CAV with their advantages and disadvantages. Further we will discuss about what are the future prospect for to increase the efficacy of vaccines.