Monkeypox Virus in Nigeria: Infection Biology, Epidemiology, and Evolution

Abstract

Monkeypox is a zoonotic disease caused by monkeypox virus (MPXV), which is a member of orthopoxvirus genus. The reemergence of MPXV in 2017 (at Bayelsa state) after 39 years of no reported case in Nigeria, and the export of travelers' monkeypox (MPX) from Nigeria to other parts of the world, in 2018 and 2019, respectively, have raised concern that MPXV may have emerged to occupy the ecological and immunological niche vacated by smallpox virus. This review X-rays the current state of knowledge pertaining the infection biology, epidemiology, and evolution of MPXV in Nigeria and worldwide, especially with regard to the human, cellular, and viral factors that modulate the virus transmission dynamics, infection, and its maintenance in nature. This paper also elucidates the role of recombination, gene loss and gene gain in MPXV evolution, chronicles the role of signaling in MPXV infection, and reviews the current therapeutic options available for the treatment and prevention of MPX. Additionally, genome-wide phylogenetic analysis was undertaken, and we show that MPXV isolates from recent 2017 outbreak in Nigeria were monophyletic with the isolate exported to Israel from Nigeria but do not share the most recent common ancestor with isolates obtained from earlier outbreaks, in 1971 and 1978, respectively. Finally, the review highlighted gaps in knowledge particularly the non-identification of a definitive reservoir host animal for MPXV and proposed future research endeavors to address the unresolved questions.

Keywords: Nigeria; Poxviridae; antiviral drugs; epidemiology; gene loss; monkeypox viruses; orthopoxviruses; phylogeny; recombination; signaling.

Figure 1

Map of Nigeria [148], reproduced with permission from the authors and Oxford University Press (Oxford, England).

Figure 2

(A) Total MPXV cases across affected states in Nigeria, in 2017. (B) Human MPXV cases across Nigeria states, in 2019.

Figure 3

All human MPXV cases in Nigeria over the years.

Figure 4

Maximum Likelihood (ML) phylogeny of orthopoxvirus genomes. Full-length genome sequences of 53 OPVs, including 23 MPXVs, were retrieved from The Virus Pathogen Database and Analysis Resource (ViPR) website [172]. The genomes were aligned with MAFFT version 7 [174]. The full-length genome alignment was stripped of gaps, and phylogenetic analysis was conducted, using Maximum Likelihood algorithm, as implemented in MEGA X [175]. Bootstrapping was set to 1000 replicates, and a General Time Reversal (GTR) model was used, as suggested by JModel test [181].