In most cases, maedi-visna virus infection is characterised by a subclinical, persistent virus-carrier state. However, in heavily infected flocks, economically significant disease does occur, mainly apparent as ill-thrift and chronic respiratory disease (maedi) in older ewes and as an indurative mastitis, which can result in delayed weight gain of suckled lambs. Meningoencephalitis (visna) and arthritis may also occur. Maedi-visna virus, a lentivirus, replicates via proviral intermediary DNA copies of its RNA genome in circulating monocytes, in which replication is highly restricted, and in tissue macrophages, where viral genome expression is more evident. The presence of macrophages expressing viral antigens on their surface in lungs, udder, joints or central nervous system tissues provides a focus for a local mononuclear cell inflammatory response. Factors which may contribute to macrophage activation and the development of the inflammatory response are discussed in the context of virus replication, transmission of infection and disease susceptibility.
Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.