Avian Leukosis Viruses

Solving the complications of oncogenesis caused by retroviruses is a challenging task for veterinary and biomedical scientists. Avian Leukosis viruses (ALVs) are a group of avian oncogenic retroviruses that can cause neoplastic diseases in chickens. The viral invasion starts due to the interaction between glycoproteins in the viral envelop and receptor sites of host cells. The pathogenesis of ALVs could be explained by three theories which include promoter insertion, enhancer activation, and the presence of oncogenes in their genome. Additionally, these viruses show great diversity due to the high mutational rate that enables them to escape from the action of the host immune system and antiviral drugs. Therefore, due to the high mortality rate of chickens, ALVs are responsible for huge economic losses in the poultry industry. Due to horizontal amp; vertical transmission and genetic variations, there is no effective vaccine to prevent infections of ALVs. The aim of this chapter is to summarize various research aspects related to the pathogenesis and transmission of ALVs. It is essential to understand these processes to get further insight into the biology of ALV’s. Likewise, to design the control strategies for ALV infections, it is invaluable to explore the interactions between ALVs and host immunity.