A Phylogeographic Investigation of African Monkeypox

Abstract

Monkeypox is a zoonotic disease caused by a virus member of the genus Orthopoxvirus and is endemic to Central and Western African countries. Previous work has identified two geographically disjuct clades of monkeypox virus based on the analysis of a few genomes coupled with epidemiological and clinical analyses; however, environmental and geographic causes of this differentiation have not been explored. Here, we expand previous phylogenetic studies by analyzing a larger set of monkeypox virus genomes originating throughout Sub-Saharan Africa to identify possible biogeographic barriers associated with genetic differentiation; and projected ecological niche models onto environmental conditions at three periods in the past to explore the potential role of climate oscillations in the evolution of the two primary clades. Analyses supported the separation of the Congo Basin and West Africa clades; the Congo Basin clade shows much shorter branches, which likely indicate a more recent diversification of isolates within this clade. The area between the Sanaga and Cross Rivers divides the two clades and the Dahomey Gap seems to have also served as a barrier within the West African clade. Contraction of areas with suitable environments for monkeypox virus during the Last Glacial Maximum, suggests that the Congo Basin clade of monkeypox virus experienced a severe bottleneck and has since expanded its geographic range.

Emergence of Monkeypox as the Most Important Orthopoxvirus Infection in Humans

“…However, Nakazawa et al suggest that the 10.8–kb sequence duplicate represents a single mutation event and is not sufficient evidence to suggest an independent evolutionary trajectory given the Sudan isolate's overall similarity to the Congo Basin isolates. Their results support a hypothesis that the virus was imported, most likely from northern DRC ( 82 ).…”

“…Firstly, poxviruses were shown to be capable to rapidly adapt against host defenses despite their low mutation rates ( 117 ). Secondly, multiple countries were projected to have a suitable environment for MPXV by ecological niche modeling ( 82 ) where MPXV might be circulating undetected in animal hosts. In these countries, evolutionary, ecological, or epidemiologic changes could tip the balance in favor of emergence and possibly sustained transmission ( 23 ).…”

A Cross-Sectional Serosurvey of Anti-Orthopoxvirus Antibodies in Central and Western Africa

“…It is not clear why monkeypox occurs more frequently in the Congo Basin than in other African regions. This can only partly be explained by the fact that the Central African strains are more virulent and able to cause human-to-human transmission more efficiently than the West African strains [ 44 , 45 , 46 ]. Human cases of monkeypox have not been reported in West Africa for decades, although ecological niche models predict areas of suitable ecology in this part of Africa and wildlife studies show that MPXV is indeed present [ 11 , 13 , 16 , 47 ].…”

Monkeypox — Enhancing public health preparedness for an emerging lethal human zoonotic epidemic threat in the wake of the smallpox post-eradication era

“…Lymphadenopathy is common and may be a clinical distinguishing feature from smallpox. Laboratory tests available for confirming a diagnosis of monkeypox include Polymerase chain reaction (PCR), antigen detection tests, Enzyme-linked immunosorbent assay (ELISA) and viral cell culture (PHE, 2018;CDC, 2018) Based on clinical and epidemiological features,and linking genotypic studies of monkeypox virus isolates two distinct clades of virus have been characterized Nakazawa et al, 2015): Congo Basin (CB) and West African (WA). The CB clade is associated with higher (approximately 10%) mortality and seems to transmit more frequently between humans with several humanto human transmission cycles.…”