Jaagsiekte sheep retroviruses (JSRVs) are a group of retroviruses that primarily infect sheep and cause a contagious lung disease known as ovine pulmonary adenocarcinoma (OPA), also referred to as Jaagsiekte. These retroviruses belong to the genus Betaretrovirus and are classified under the family Retroviridae.
JSRVs are spherical in shape and possess a single-stranded RNA genome, which is converted into double-stranded DNA after infecting the host cell. They typically target the epithelial cells lining the lungs, causing a range of lesions and tumors in the respiratory system.
The transmission of JSRVs is primarily through the respiratory route, wherein infected animals shed viral particles through their respiratory secretions. Healthy sheep can contract the virus by inhaling these particles or through direct contact with infected animals. The infection is not limited to sheep and has been found to affect goats and mouflons as well.
The hallmark of JSRV infection is the development of lung tumors, which gradually impair the respiratory function and lead to weight loss, coughing, labored breathing, and eventually, death. These tumors are composed of transformed cells that proliferate uncontrollably, disrupting the normal lung architecture.
Efforts have been made to develop vaccines and diagnostic tests for JSRVs, but currently, there is no specific treatment available. Management strategies mainly focus on prevention and control measures like quarantine, culling infected animals, and improving general flock health.
Understanding the biology and pathogenesis of Jaagsiekte sheep retroviruses is vital not only for the health and welfare of sheep but also for elucidating the mechanisms of retrovirus-induced tumorigenesis in mammals, including humans.
