Effect of interferons on the replication of alcelaphine herpesvirus-1 of malignant catarrhal fever. – PubMed

These viruses share contrasting abilities to propagate infectious virus without inducing clinical signs within specific reservoir host species (sheep for OvHV-2; wildebeest (Connochaetes taurinus) for AlHV-1; Topi (Damaliscus lunatus) for AlHV-2; and goat for CpHV-2) and also to induce fatal MCF, without the production of infectious virus, in selected MCF-susceptible species including bison (Bison bonasus), cattle, deer and others [11]-[12]. C. Experimentally, MCF can be induced and infectivity maintained by inoculation of infected cells in to susceptible hosts [17,18] or by intranasal inoculation with cell-free virus [19,20]. Malignant catarrhal fever (MCF) is a dramatic, fatal disease of cattle and other ungulates, including deer, bison and pigs, caused by ruminant gamma-herpesviruses of the genus Macavirus including Alcelaphine herpesvirus 1 (AlHV-1) and Ovine herpesvirus-2 (OvHV-2) (Loken et al., 1998; Reid et al., 1984; Schultheiss et al., 2000). Lambs are infected usually at 3–6 mo of age by aerosol transmission from other individuals within the flock and begin to actively shed virus at ~6–9 mo of age. In sub-Saharan Africa, cross-species transmission of AlHV-1 to susceptible host species occurs throughout wildebeest grazing areas and largely affects cattle.

In addition, most of CD8+ T cells secreted IFN-γ demonstrating that this cell population display a strong activation status. Transcription of late mRNAs by host polymerase II, encoding structural proteins. Digestion of each construct and the parental bacterial artificial chromosome (BAC) DNA with two restriction enzymes, one that does not cut (SpeI) and another that cuts (EcoRI) within the recombined region (Fig. Using this mutant virus, we tested the overall hypothesis that AlHV-1 with its glycoprotein B (gB) gene replaced by the OvHV-2 homologous gene can replicate in vitro and is infectious to rabbits. There is a lack of good transmission and epidemiological work on MCF that requires to be done to address such issues. These viruses are carried asymptomatically by their natural hosts, the wildebeest (Connochaetes taurinus) in the case of AlHV-1 and the domestic sheep (Ovis aries) in the case of OvHV-2.

These data are consistent with disease-induced stimulation of inflammatory responses involving interferon-γ, including cytotoxic T cell recruitment and activation in peripheral tissues containing virus-infected cells. This is the most promising immunisation strategy to date for the control of malignant catarrhal fever. Two polypeptides were detected in only the virulent virus preparations, while one other protein was found in only the attenuated virus. Empirical analysis showed that a recombinant haemagglutinin-tagged A9.5 fusion protein was secreted from transfected cells and had a molecular mass of 45 kDa, which was reduced to 20 kDa by endoglycosidase F treatment, confirming that A9.5 was a secreted glycoprotein. To reach that goal, a recombinant AlHV-1 strain was produced by insertion of a luciferase expression cassette (luc) in an intergenic region. The main causative agents of MCF are two closely-related gammaherpesviruses, Ovine herpesvirus 2 (OvHV-2) and Alcelaphine herpesvirus 1 (AlHV-1).

Rabbits were identified according to the day of euthanasia postinfection (see numbers). In the genome of the attenuated virus, there are also two copies of the 2 kbp sequence but they are located at the ends of the attenuated genome unique region, adjacent to the terminally repeated sequences. These results are discussed particularly with respect to the involvement of BHV-3 in malignant catarrhal fever. Here, we further studied the mononuclear leukocytic populations in both the lymphoid (throughout the infection and at time of euthanasia) and non-lymphoid (at time of euthanasia) organs during WD-MCF induced experimentally in rabbits. A2ΔAlHV-1-infected rabbits succumbed to MCF, albeit with a delayed onset compared to the control groups, so A2 is not a critical virulence factor. A2DeltaAlHV-1-infected rabbits succumbed to MCF, albeit with a delayed onset compared to the control groups, so A2 is not a critical virulence factor.

Similarly to other viral genome maintenance proteins encoded by gammaherpesviruses, aLANA has recently been shown to be essential for viral persistence and induction of MCF. The 130 kilobase pair (kbp) AlHV-1 double stranded DNA genome consists of 18 open reading frames (ORFs) coding for structural proteins and approximately 50 ORFs coding for non-structural proteins. Two viral loci were sequenced to examine variation among virus samples obtained from wildebeest and cattle: the ORF50 gene, encoding the lytic cycle transactivator protein, and the A9.5 gene, encoding a novel polymorphic viral glycoprotein.