Malawi polyomavirus (MWPyV), also known as human polyomavirus 10 or Mexico polyomavirus, is a non‑enveloped double‑stranded DNA virus that infects humans. It was discovered in 2012 after independent reports from Africa and the Americas and is recognized as the tenth human polyomavirus.
Explanation
MWPyV was first identified in stool samples from a healthy child in Malawi and soon after in children in Mexico and the United States, leading to the names Malawi polyomavirus, Mexico polyomavirus and human polyomavirus 10. It was subsequently included in the International Committee on Taxonomy of Viruses classification as a member of the genus Deltapolyomavirus, which also contains HPyV6 and HPyV7. The circular genome is about 4.9 kilobases long and encodes the small and large T antigens along with three structural proteins, VP1, VP2 and VP3. Sequence variation among isolates can reach 5 %, reflecting the heterogeneous nature of the virus, yet the gene organisation remains similar to that of other polyomaviruses. Serologic surveys in immunocompetent adults suggest that antibodies to MWPyV are common, with seroprevalence estimates ranging from approximately 40 % to 85 %. Most individuals acquire infection during early childhood, as evidenced by the high proportion of seropositive children and the low detection of viral DNA in adults. When active replication is measured via detection of viral DNA, MWPyV is found in around 1 % to 10 % of children. In terms of clinical relevance, MWPyV has been detected in stool samples from both healthy and diarrheic children and occasionally in respiratory secretions. There is no clear causal link between the virus and human disease; the detection in warts from an immunodeficiency syndrome patient appears incidental and not a consistent finding.
Key observations and facts
– MWPyV is the tenth human polyomavirus, discovered independently in multiple countries in 2012. – Its 4.9 kb genome follows the typical polyomavirus organisation, encoding the small and large T antigens and capsid proteins VP1, VP2 and VP3. – Sero‑studies show that 40–85 % of adults have antibodies to MWPyV, while active viral DNA is detected in 1–10 % of children. – The virus is usually found in stool samples and occasionally respiratory secretions of young children, with no confirmed association with disease. MWPyV is a common yet understudied human polyomavirus. Its widespread seropositivity suggests early and frequent exposure, but there is little evidence that it causes illness. Continued surveillance will clarify its biology and interactions with other members of the Deltapolyomavirus group. Related Terms: Human Polyomavirus 6 (HPyV6), Human Polyomavirus 7 (HPyV7), STL Polyomavirus (STLPyV), New Jersey Polyomavirus (NJPyV), Deltapolyomavirus