Malignant catarrhal fever: inching toward understanding.

Malignant catarrhal fever (MCF) is an often lethal infection of many species in the order Artiodactyla. It is caused by members of the MCF virus group within Gammaherpesvirinae. MCF is a worldwide problem and has a significant economic impact on highly disease-susceptible hosts, such as cattle, bison, and deer. Several epidemiologic forms of MCF, defined by the reservoir ruminant species from which the causative virus arises, are recognized. Wildebeest-associated MCF (WA-MCF) and sheep-associated MCF (SA-MCF) are the most prevalent and well-studied forms of the disease. Historical understanding of MCF is largely based on WA-MCF, in which the causative virus can be propagated in vitro. Characterization of SA-MCF has been constrained because the causative agent has never been successfully propagated in vitro. Development of molecular tools has enabled more definitive studies on SA-MCF. The current understanding of MCF, including its etiological agents, epidemiology, pathogenesis, and prevention, is the subject of the present review.

La forme africaine du coryza gangreneux est une maladie lymphoproliférative létale causée par l'herpèsvirus alcélaphin 1.

Gammaherpesviruses include viruses able to induce lymphoproliferative diseases and tumors. These viruses can also establish a long and persistent asymptomatic infection in their natural host. Among gammaherpesviruses, AlHV-1 belongs to the Macavirus genus and infects asymptomatically its natural host, the wildebeest (Connochaetes spp.). However, this virus induces a lethal lymphoproliferative disease named the African form of malignant catarrhal fever (MCF) when transmitted to a large number of susceptible species belonging to the Artiodactyla order. Control of MCF in regions where AlHV-1 is endemic is of great importance and directly depends on the understanding of the pathogenic mechanisms responsible for the induction of MCF. The goal of the present review is to summarize current knowledge on AlHV-1 and MCF with a particular interest on the mechanisms used by AlHV-1 to induce the disease. Amongst different models of pathogenesis, the particular role of viral latency will be addressed based on current data. Finally, the evolutionary relationship between the wildebeest, AlHV-1 and the susceptible species to MCF will be discussed.

The Gamma Herpesvirus Alcelaphine Herpesvirus 1 Causes Apoptotic Infection in Permissive Cell Lines

Apoptosis is a host defense mechanism that the cell uses to limit production of infectious virus. Although many viruses can induce apoptosis in infected cells, large DNA viruses, such as poxviruses, herpesviruses and adenoviruses, usually exhibit the ability to suppress the induction of apoptosis in the infected cells. Several publications have attested to the ability of herpesviruses to protect cells against apoptosis. We investigated the ability of the virus to protect cells in continuous cultivation from apoptosis induced by the virus itself. The gamma herpesvirus alcelaphine herpesvirus 1 (AlHV-1) has been shown to harbor genes with antiapoptotic potentialities. However, here we have demonstrated that productive infection of adherent, permissive cell lines by AlHV-1 resulted in a cytopathic effect characterized by induction of apoptosis. This phenomenon was confirmed using different techniques to detect apoptosis and using different virus strains and cell lines. Therefore, despite the presence of antiapoptotic genes in its genome, AlHV-1 could complete its cycle of productive infection while inducing apoptosis of infected cells. This finding might have implications for the pathobiology of AlHV-1 and other gamma herpesviruses in vivo.