Avian retroviruses

Abstract

Background and Aim. Avian retroviral infections, particularly avian leukosis virus (ALV) and reticuloendotheliosis virus (REV), pose a severe threat to the modern poultry industry. The ability of these viruses to include immunosuppression and neoplastic processes leads to heightened avian susceptibility to concurrent infections (such as avian influenza and Newcastle disease), diminished vaccination efficacy, and substantial hidden economic losses. Despite the active circulation of various ALV genetic variants and reported REV outbreaks in neighboring countries (China, Russia), data regarding their prevalence in Kazakhstan remain extremely limited. This review aimed to synthesize current knowledge on retrovirus biology, raise awareness among veterinary professionals regarding the hidden threat of ALV and REV, and substantiate the necessity of implementing systematic control of these infections at poultry facilities.

Material and Methods. A comprehensive analysis of current scientific literature addressing the biology, classification, life cycle, and molecular mechanisms of retrovirus-host cell interactions was conducted. The role of exogenous and endogenous retroviruses in the development of infectious and oncological diseases was examined. Additionally, available information on the epizootiological situation in countries bordering Kazakhstan was reviewed, alongside contemporary approaches to the diagnosis, therapy, and prevention of retroviral infections.

Results. The analysis demonstrated that ALV and REV possess high genetic variability and the capacity to establish persistent infections through integration into the host genome. It was established that these infections frequently progress subclinically: virus-induced lymphoblastomas and internal organ lesion often remain undetected, while outbreaks of concurrent infections are erroneously attributed to poor vaccine quality. A broad range of susceptible hosts (domestic and wild birds) and the active circulation of these pathogens in border regions were identified as key factors creating a high risk of introduction into Kazakhstan, where systematic molecular epidemiology monitoring is currently absent.

Conclusion. The implementation of comprehensive molecular genetic testing and continuous monitoring of avian retroviruses in Kazakhstan is critical to ensure the biosecurity of poultry enterprises, mitigate economic damage, and develop effective strategies for the control and prevention of ALV and REV, as well as the protection of flocks.