"Yaba Monkey Tumor Virus"...can you repeat that slowly please?
Multiple skin lesions on the forearm of a Vervet monkey, caused by Yaba Monkey Tumor virus.
Phylogenetic tree showing the genetic relatedness of this pox sample to reference sequences of Yaba Monkey Tumor virus. From the tree, and the position of the samples on the branches, it is clear that this sample (indicated with an arrow) is genetically most similar to other YMTV sequences and genetically distant from Tanapox, Lumpy Skin Disease and Monkeypox.
YMTV was first diagnosed in captive Asian rhesus monkeys (pictured) and a baboon in Yaba, Nigeria. (Image: Wikimedia)
Most of us are aware that humans can (or could) get infected with a pox virus, namely Smallpox or Variola virus. Fortunately this disease has been eradicated worldwide since 1980 through an extensive vaccination programme.
Animals are not so lucky, and seem to have their own set of pox viruses still doing the rounds. Most of the members of the Poxviridae cause mild skin disease (hence the name "pox"), but some can cause severe systemic disease in birds (Fowlpox) and mammals (Sheeppox virus, Fowlpox virus, Ectromelia virus and Monkeypox virus).
Some viruses are also renowned for the economic losses they cause, such as Lumpy skin disease in cattle and Sheep and Goat pox in small ruminants. These viruses are nasty little guys to be reckoned with, and the accurate identification of the viral species is very important for the proper treatment and containment of these diseases.
When in August last year a Vervet monkey from KwaZulu-Natal was found with a pox-like lesion on her arm, the correct identification of the causative agent was understandably of high importance. The help of wildlife pathologist Dr Emily Lane and molecular biologist, Dr Helene Brettschneider from the Research Department at the NZG was called in to identify the virus. From histopathological examination, Dr Lane confirmed the presence of a pox virus, and then it was up to the molecules to prove their worth!
DNA was extracted from the lesion sample and - using specific markers designed for pox viruses - the NZG researchers were able to sequence a section of the pox DNA polymerase gene region. This gene is vital to the effective replication of the pox virus in its host, and therefore remains relatively conserved in the pox genome, making it ideal for species identification.
Phylogenetic analyses compared the sequences obtained from this case to reference sequences available in the Genbank database, and confirmed the species to be a Yaba Monkey Tumor Virus. This analysis also revealed the sample to be genetically distinct from Tanapox, Lumpy Skin Disease as well as Monkeypox.
Yaba Monkey Tumor Virus (YMTV)
YMTV was first diagnosed in a colony of captive Asian rhesus monkeys (Macaca mulatta) and a baboon (Papio papio) in Yaba, Nigeria. Thereafter, YMTV has been identified as the cause of skin lesions in baboons (Papio spp), Asian rhesus (Macaca mulatta) and Cynomolgus monkeys (Macaca fascicularis) in the UK and USA.
This seems to be the first report of YMTV in South Africa, and in Vervet monkeys, thanks to collaboration with Dr Peter Biden (the veterinarian), Dr Jan Vorster (the pathologist who sent the case to the NZG for specialist tests), and technological advances in the fields of wildlife pathology and molecular genetics.
Although the importance of the virus to non-human primates in South Africa is not known, infections in monkeys are reported to resolve with lasting immunity and the researchers are happy to report that the Vervet monkey is recovering well.
YMTV and humans
YMTV, like many other primate diseases, may be transmissible to humans. The NZG therefore recommends that the public as well as animal handlers and curators are advised to wear gloves and a face mask when having close contact with monkeys or baboons. YMTV can also be transmitted by mosquito bites, so if you live in an area where primates are common or you handled a primate recently, please notify your medical doctor if you develop skin lesions or nodules.
By Helene Brettschneider, Emily Lane and Antoinette Kotze, NZG
Dr Helene Brettschneider is a postdoctoral researcher at the Molecular Genetics unit of the Research Department at the NZG. Her research focusses on the development of molecular techniques for the detection and identification of wildlife pathogens.
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