Researchers from the National Institute of Health Doutor Ricardo Jorge (INSA), Lisbon, Portugal have shared the draft genome sequence of the monkeypox virus that is rapidly spreading in many European countries. The draft sequence has been posted at the virolgical.org site.
The released draft genome sequence covers about 92% of the reference sequence. The sample was obtained from a swab collected on May 4 from skin lesions from a male patient in Portugal. As on May 19, Portugal had reported over 20 laboratory-confirmed cases of monkeypox.
Draft genome sequence
Researchers from Belgium — the Institute of Tropical Medicine, Antwerp, and the University of Antwerp, Antwerp — too have shared a draft genome sequence of monkeypox at the virolgical.org site. The researchers were able to reconstruct 98.9% of the genome.
The genome was sequenced from a sample collected from a person in Belgium. The 30-year-old male in Belgium has a travel history to Lisbon, Portugal.
In the month of May 2022, many cases of monkeypox have been reported from at least 11 countries and there were about 80 confirmed cases, and 50 pending investigations, the WHO tweeted on May 20.
According to the New Scientist, 127 cases have been identified by May 21. The cases are mainly from Europe — Portugal, the United Kingdom, Spain, France, Italy, Sweden, Belgium — and the U.S.
Monkeypox is not endemic in Europe or the U.S. but is endemic in a few Central and West African countries. The virus is transmitted from one person to another by close contact with lesions, body fluids, respiratory droplets and contaminated materials.
Phylogenetic analysis
Based on rapid phylogenetic analysis of the draft genome, the researchers have found that the virus now spreading outside Africa belongs to the West African clade. According to the New Scientist, the virus belonging to the West African clade is mild in nature.
“The phylogenetic analysis of the draft genome indicates that the 2022 virus belongs to the West African clade and is most closely related to viruses associated with the exportation of monkeypox virus from Nigeria to several countries in 2018 and 2019, namely the United Kingdom, Israel and Singapore,” write the Portuguese researchers.
And the genome sequenced from the male in Belgium appears to be closely related to the genome shared by the researchers from Portugal. “Preliminary phylogenetic analysis clearly shows that the obtained genome belongs to the West African clade of MPXV [monkeypox] and is most closely related to the recently uploaded genome from the outbreak in Portugal providing further evidence of substantial community spread in Europe,” the researchers from Belgium write. The increased number of cases from multiple countries have raised concerns about enhanced human-to-human transmission of the virus. Evidence about increased human-to-human transmission, which is possible only if the virus has undergone any changes to make it easily transmissible among humans, will come from detailed genome sequence analysis.
Virus transmissibility
According to the New Scientist, establishing increased transmissibility of the virus that is currently circulating in Europe, the U.S. and Canada will take time as monkeypox has a “large [around 200,000 DNA letters long] and complex genome”. The current outbreak outside Africa is the most widespread and also the largest till date.
According to Nature News, monkeypox has been detected in people who have not come in contact with those with monkeypox infection, which suggests that the virus might been spreading silently. In a statement issued on May 20, the WHO regional director for Europe too said that the “geographically dispersed nature of the cases across Europe and beyond, suggests that transmission may have been ongoing for some time”. Also, except in one case, there has been no travel history to areas in West or Central Africa where the monkeypox virus is endemic.
Monkeypox usually causes very visible skin lesions and hence cannot go unnoticed. The silent spread, if true, might mean that the virus is able to also spread without causing symptoms in some infected people. If monkeypox can indeed spread asymptomatically then it would make it harder to track the virus, Andrea McCollum, an epidemiologist at CDC Atlanta told Nature News.
“As more samples are sequenced, it should become clear whether, as suspected, a single variant of monkeypox is responsible for all the cases in the latest outbreak,” the New Scientist notes.
