Page 18 - VHSA - Onderstepoort 100 Years - Part 3

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ERSTEPOORT 100
In 1988 the development of the polymerase chain reaction (PCR), using a thermostable polymerase, dramatically increased the sensitivity of these tests and it was soon to become the gold standard in DNA diagnostic technology. It was first used for the detection of Anaplasma DNA by Visser. In 1991 another milestone was reached when York, working as a visiting scientist in France, completed the sequencing of the genome of the jaagsiekte retrovirus. It was
an important achievement at the time, being the first full sequence of a genome obtained by a South African scientist. Although he returned to the University of Natal shortly afterwards, York continued his work on jaagsiekte under contract for the Institute for a number of years. Most interesting was his discovery of an endogenous form of the virus which is universally present in
the genomes of sheep and is non-oncogenic. This discovery explained why sheep do not produce antibodies to JSRV, which is because it is not recognized as foreign.
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seemed to enhance the infectivity of the latter. It turned out to be a lentivirus, related to the human HI-virus, and is thought to act similarly through immuno-suppression. By this time the group had been joined by two new members, D.F. (Dennis) York and M.S. (Martin) Myer, who respectively studied the new virus and the putative immunological interactions. Immuno- suppression could not be demonstrated but York managed to isolate and characterize the lentivirus in collaboration with researchers in France.
In 1986 Verwoerd was promoted to the position of Deputy Director of the Institute. His successor as head of the Mole- cular Biology Section was R.E. (Richard) Ambrosio. By then de Villiers had left for Germany where she distinguished herself as a cancer virologist and Williamson had returned to her alma mater, the University of Cape Town, joining an active group working on human viruses. York continued with his studies on the jaagsiekte virus but Ambrosio decided to apply his skills in molecular genetics to a different group of pathogenic organisms. With the aid of three new assistants, E.S. (Elsa) Posnett, E.S. (Betty) Visser and S. (Fanus) Wilkens, genomic libraries were constructed for Anaplasma centrale, Babesia bovis, B. equi, Ehrlichia (previously Cowdria) ruminantium and Mycobacterium paratuberculosis. From these libraries diagnostic probes were prepared, but cost and other factors prevented their adoption for practical diagnostics.
Molecular parasitology
Also in 1991, Ambrosio left the Institute for a position in the private sector. He was replaced by B. A. (Basil) Allsopp, who was recruited from the University of Cambridge, UK, together with his wife, M. T. (Paula) Allsopp from King’s College, London. Basil Allsopp was trained as a biochemist at Imperial College, London, and had spent 18 years in East Africa where he was involved in research on several tropical animal diseases. While working at the Veterinary Research Organization and later at ILRAD in Kenya, his main interest had been East Coast fever (ECF) in cattle which is caused by infection with Theileria parva. This is a tick-borne disease which was, and still is, endemic throughout East Africa.
Theileria parva was introduced into South Africa from Tanzania via Mozambique in 1902 and subsequently wreaked havoc in the cattle population. It eventually took 50 years to eradicate it from South Africa, by an expensive dipping and slaughter-out policy, but related endemic T. parva parasites still existed in African buffaloes which cause Corridor disease when passed into cattle. In order to prevent the spread of Corridor disease in cattle the movement of buffaloes is strictly controlled and animals can only be translocated if they test negative for T. parva. Such animals fetch very high prices, and to improve the sensitivity and specificity of the diagnosis B.A. Allsopp
PART 3
History of Individual Disciplines
1908-2008
Years