Faculty of Natural and Agricultural Sciences
Department of Microbiology and Plant Pathology
Rabies and other zoonotic viruses
We are concerned with several animal viruses - in particular those that are zoonotic in nature (transmissible from vertebrate animal to man). In general, our research focuses on the continual improvement in the capability to detect, control and treat these viral diseases, based on knowledge and understanding of, amongst others, viral epidemiology, evolution, pathogenicity and mechanisms of infection.
Our main focus is on rabies and rabies-related viruses. These viruses belong to the genus Lyssavirus (lyssa = mad) in the family Rhabdoviridae. The lyssaviruses (the only rhabdovirus to infect man) has evolved exceptional biological properties. Uniquely, lyssaviruses are both neuro-invasive and neuro-virulent and rabies virus has the highest case fatality ratio of all viruses. Rabies virus is thought to be infective to all mammals. In particular, the virus is well established in carnivore populations (dogs, foxes, raccoons, skunks etc) all around the world. Ancestral lyssaviruses are arguably from Africa and include Lagos bat virus. These viruses are not well understood and our next aim in lyssavirus pathogenesis research is to better elucidate the ecology of bat lyssaviruses within their natural reservoirs. These viruses have been adapted to bat hosts for millennia, whereas terrestrial rabies virus is a relatively new adaptation to its wise range of carnivore hosts and reservoirs. Our research of rabies-related viruses includes passive and active surveillance and epidemiological studies of host range and the activity and overlap of endemic infection cycles. We explore genomics and study the molecular biology and genetic diversity of virus isolates, including studies of the cumulative role of mutations in virus pathogenicity. In laboratory studies of pathogenicity, we study the infection process and development of disease in natural hosts, ie bat species.
We provide research support to, amongst others, the KZN dog rabies elimination program. There are several components to this - including vaccinology, epidemiology, diagnostics, primary health care, human health and dog ecology. Vaccine projects explore new and alternative vaccines - particularly for oral vaccination of dogs, but include immune contraception for dogs as an adjunct to rabies control through population management. We also research dog ecology, a crucial but easily neglected aspect to the control of rabies in dogs. Diagnostic methodology remain on our research agenda as we continue to search for more effective ways to assist with the single most neglected aspect of rabies in the developing world, viz. adequate laboratory-based diagnosis and surveillance. In rabies research another notable research project investigates the unique occurrence of rabies in ruminants (kudu) in Namibia. We are studying the epidemiology and virus (molecular) properties and will explore solutions to this devastating epidemic. In a further new programme (2011-2014) we will cooperate with, amongst others, the government of Mozambique in providing technical and research support to assist with rabies control in that country.
Apart from our focus on rabies and other lyssaviruses and the involvement of bats in the evolution and epidemiology of these viruses, we are well aware that almost three quarters of emerging infectious diseases in humans are zoonotic in nature and that bats have been increasingly associated with the emergence of novel zoonotic viruses during the past two decades - including SARS-CoV, Hendra, Ebola and Marburg viruses. Bats have certain characteristics believed to contribute to their propensity to act as reservoirs of pathogens and their ability to fly allows for the possibility of long distance dispersal of pathogens. Our research therefore also includes the use of sequence dependent as well as sequence independent methods to identify pathogens other than lyssaviruses that are present in African bats. Surveillance for known pathogens and the discovery of new organisms is a first step towards understanding their diversity, evolution, epidemiology, impact and disease control.
|
