The monkeypox virus (MPXV) is the causative agent of the monkeypox disease. As a double-stranded DNA virus member of the genus Orthopoxvirus and the family Poxviridae, MPXV is similar to…
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The monkeypox virus (MPXV) is the causative agent of the monkeypox disease. As a double-stranded DNA virus member of the genus Orthopoxvirus and the family Poxviridae, MPXV is similar to other pathogens of this group including variola (the causative agent of smallpox), vaccinia, and the cowpox virus. On average, the case fatality rate of monkeypox is 10%, between the high rate of variola major (30%) and the low rate of variola minor (1%).
Monkeypox is recognized by experts as an emerging zoonotic disease, the most prominent orthopoxvirus infection in humans since the eradication of smallpox. This virus can infect a wide range of mammalian species, but its natural host and reservoir are yet to be described.
The first human case of the monkeypox disease was detected in 1970 in the Democratic Republic of the Congo. Since then, the infection spread to other Central and West African countries, eventually giving rise to two genetically distinct clades: the West African and the Central African clades, also known as the Congo Basin clade.
The virus is endemic to these regions but recent outbreaks have been reported in other countries. Before the 2022 outbreak, several monkeypox cases caused by a West African MPXV strain were reported in the U.S. in 2003. Detected in a broad range of species including humans, the source of this outbreak was traced back to the importation of monkeypox-infected West African rodents. Several other outbreaks outside of the endemic region have been reported since then.
Since May 2022, hundreds of new cases of monkeypox have been detected across 25+ countries. The majority of the confirmed cases were detected in Europe (87%, source: WHO, June 8, 2022) and the Americas (12%). Genomic data obtained by researchers in Portugal and the U.S. confirmed a high level of similarity between strains isolated in both continents. Moreover, phylogenetic analysis suggests the new virus possibly belongs to the West African clade.
Researchers from the National Institute of Health Doutor Ricardo Jorge (INSA, Lisbon, Portugal) have recently published the first genetic analysis of the outbreak virus suggesting that the multi-country epidemic most likely has a single origin and it is the most similar to the monkeypox outbreak originated in Nigeria in 2018/2019. The virus has an unusually high number of SNPs (single nucleotide polymorphisms) in comparison to the strains isolated in previous outbreaks, suggesting that it might have resulted from an evolutionary jump. Preliminary analysis also correlates with human-to-human transmission, although further evidence is still needed.
The UK Health Security Agency (where over 300 cases have been reported) currently advises the prioritization of surveillance efforts and virology studies (genomics and functional characterization). Conventional nucleic acid tests able to distinguish monkeypox from the other orthopoxviruses are currently scarce due to the high level of similarity between different orthopoxviruses (e.g., smallpox). However, little is still known about the infection dynamics of the monkeypox virus, potential mutations and subsquent biological significance, and the transmissibility of the new outbreak virus.
The lack of information warrants the rapid development of high-quality reagents for research, ranging from antigens to antibodies, which can be used to determine the role and importance of each protein in the infection and transmissibility of the disease.
