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Thursday, August 30th, 2007
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Morbilluvirus
Morbilliviruses are an antigenically related group of viruses in the family Paramyxoviridae. The type virus of the group is human Measles Virus (MV) but it also includes important animal pathogens such as Rinderpest Virus (RPV) of cattle, buffalo and wild bovids, Peste des Petits ruminants (PPR) virus, which infects mainly sheep and goats, Canine Distemper Virus (CDV) of domestic dogs and wild carnivore species, Phocine Distemper Virus (PDV) of seals and two viruses isolated from cetacean species, Dolphin morbillivirus (DMV) and Porpoise Morbillivirus (PMV).
Morbilliviruses are highly pathogenic in their hosts and the economic consequences of epizootics of rinderpest and PPR can be devastating. PPR infection is one of the most important constraints to the increased production of small ruminants in West Africa and recently severe epizootics have occurred in the Middle East and across the north of the Indian sub-continent. Rinderpest continues to pose a serious threat to cattle, buffalo and wild ruminants in parts of eastern Africa but a global eradication campaign is in place with the aim of achieving eradication of the disease by 2010. The group is actively involved in this project by helping to develop new marker vaccines and their associated serological tests and by providing scientific advice and training. A severe outbreak of PDV occurred in Northern Europe in 2002, resulting in the deaths of many seals. The group’s research interests can be divided into three main areas: Epidemiology Molecular techniques have been applied to the diagnosis of the different morbilliviruses and RT-PCR assays are available which can distinguish the different viruses in clinical and post-mortem tissues. Sequencing studies have shown that, despite being only one serotype of each virus, there are different genetic lineages of each virus and this allows tracing of disease outbreaks outside their known geographic area. Vaccinology In the field of vaccine development the group has produced both vaccinia and capripox recombinant vaccines to protect against rinderpest and PPR. The capripox recombinants act as dual vaccines, for example the PPR recombinant protects against sheep and goat pox as well as PPR infections. Currently we are developing new marker vaccines for rinderpest using reverse genetics technology. Pathogenesis The development of reverse genetics for negative-strand RNA viruses in 1994 made it possible to study the effects of specific genome changes on the nature of the virus phenotype, both in vitro and in the host animal. Revere genetics for RPV was developed in 1996 when a complete copy of the RBOK vaccine strain was rescued from cDNA. Subsequently the virulent parent of the vaccine strain was rescued for cDNA and shown to retain its virulence for cattle. It was then possible to demonstrate that the vaccine, which is safe and highly efficacious, had multiple gene mutations that explained its high attenuation and stability. In addition we were able to show that the extragenic promoter regions also had played a role in determining the pathogenic nature of the virus.  Reference list
Anderson, J., Barrett, T. and Scott, G.R. (1996) Manual on the diagnosis of rinderpest. Second edition, FAO Rome. Book Chapters
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'Dardanidae duri, quae uos a stirpe parentum prima tulit tellus, eadem uos ubere laeto
accipiet reduces. Antiquam exquirite matrem: hic domus Aeneae cunctis dominabitur oris, et nati natorum, et qui nascentur ab illis.'  We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light. --Plato-- 
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