The presumed receptivity and susceptibility to monkeypox of European animal species

A review of epidemiology, diagnosis, and management of Mpox: The role of One Health

Human monkeypox (Mpox) is an emerging zoonotic disease. Its clinical features are similar to but less severe than those of smallpox. The etiology of this disease is the monkeypox virus. This virus is a double-stranded DNA virus that is classified into the genus Orthopoxvirus and the family Poxviridae. Human monkeypox was first identified in 1970 and mainly occurred in Central and Western Africa. In 2022, outbreaks of Mpox virus infection occurred in several non-endemic countries and caused a potential threat to humans. It is urgent to take immediate action to control and prevent the outbreak of the Mpox virus infection. This paper summarizes the current status of Mpox and generated strategies for managing the Mpox epidemic. Although progress in the diagnostic methods and treatment of Mpox produces better knowledge, we argue that the sensitive surveillance for animal and human Mpox virus infection and evidence-based response and management of Mpox outbreaks is critical. This study highlights the need for further research on preventive and control strategies for Mpox disease approached through the One Health concept.

Monkeypox 2024 outbreak: Fifty essential questions and answers

As the world still vividly recalls the previous monkeypox (mpox) outbreak that impacted over 120 countries worldwide with more than 99,000 cases in 2022, we are now facing a second wave of infections from the monkeypox virus (MPXV), characterized by an exponential increase in cases. The current 2024 outbreak has already recorded more than 20,000 cases in Africa, marking a dramatic escalation compared to previous outbreaks. The predominance of the newly identified clade Ib variant, first detected in the Democratic Republic of the Congo (DRC) and now identified across multiple African nations and beyond, underscores its enhanced transmissibility and potential for international spread, evidenced by cases in Sweden and Thailand. The World Health Organization (WHO) declared on August 14, 2024, the current mpox outbreak a Public Health Emergency of International Concern (PHEIC), calling for heightened global public health measures. The ongoing pattern of unusual, frequent, and extensive outbreaks of mpox with potential global implications poses significant questions. This review addresses, in the format of 50 questions and answers, the 2024 mpox outbreak, detailing its characteristics, epidemiological data, and impact compared to previous outbreaks. It comprehensively explores critical questions related to MPXV virological characteristics, immunological response, clinical manifestations, epidemiology, diagnostics, and available treatments. The review also documents the significant and evolving challenges posed by the current mpox outbreak, highlighting its scale, spread, and public health response.

Development of a multiplex real-time PCR for the simultaneous detection of monkeypox virus clades I, II, and goatpox virus

Introduction

Monkeypox virus (MPXV) hosts are of multiple species, with a risk of cross-species transmission. This phenomenon poses a threat to unreported affected domestic animals and increases the risk to human public health. Clinical diagnostics continue to face challenges regarding specificity among poxviruses. The need for a rapid and precise assay to differentiate between MPXV clades I and II, as well as goatpox virus (GTPV) is essential for enhancing our capacity for disease prevention, control, and epidemiological investigation.

Methods

To address this need, we have successfully developed a multiplex real-time PCR assay targeting MPXV D14L gene for clade I, MPXV D18L gene for clade II, and GTPV RPO30 gene, which can simultaneously detect MPXV clades I and II as well as GTPV.

Results

The developed assay demonstrated high sensitivity, with limits of detection at 207.83 copies/reaction for MPXV clade I, 252.07 copies/reaction for MPXV clade II, and 208.72 copies/reaction for GTPV. Importantly, there was no cross-reactivity with other non-pox viruses which infect goats. The assay exhibited excellent repeatability, with coefficients of variation (CV%) for intra-assay and inter-assay ranging from 0.17% to 0.89% and 0.58% to 1.09%, respectively.

Discussion

This assay can serve as a vital resource to safeguard against the MPXV epidemic posing a threat to the life safety of goats, to mitigate potential risks to the sheep farming industry, and to prevent the transmission of MPXV to humans through sheep, which could act as a potential transmission vector for infection.

A Review of Evidence Related to the Zoonotic Characteristics of the Monkeypox Virus

The 2022 monkeypox virus (MPXV) outbreaks spurred global public health concern. In response, we undertook a living systematic review of its zoonotic characteristics, including potential reservoirs and susceptible species, transmissibility, and clinical presentation in nonhuman species. Electronic database searches yielded 148 eligible records published between 2000 and 2022. Primary reservoirs remain unidentified, with natural isolation identified in 2 species, the sooty mangabey monkey and rope squirrel. Transmission primarily occurs from animals to humans, but evidence of reverse zoonosis has emerged. Data on clinical infection and manifestations are sparse, with evidence of potentially susceptible species drawn primarily from experimental studies. Only 10% of articles were appropriate for quality assessment and most of these were rated as critically low. Overall, while evidence regarding MPXV exists, the quality of data are extremely poor, resulting in significant uncertainty regarding MPXV's zoonotic traits. High-quality empirical research to understand the impact of MPXV on animal and human populations is warranted.

Molecular Evolution of Protein Sequences and Codon Usage in Monkeypox Viruses

The monkeypox virus (mpox virus, MPXV) epidemic in 2022 has posed a significant public health risk. Yet, the evolutionary principles of MPXV remain largely unknown. Here, we examined the evolutionary patterns of protein sequences and codon usage in MPXV. We first demonstrated the signal of positive selection in OPG027, specifically in the Clade I lineage of MPXV. Subsequently, we discovered accelerated protein sequence evolution over time in the variants responsible for the 2022 outbreak. Furthermore, we showed strong epistasis between amino acid substitutions located in different genes. The codon adaptation index (CAI) analysis revealed that MPXV genes tended to use more non-preferred codons compared to human genes, and the CAI decreased over time and diverged between clades, with Clade I > IIa and IIb-A > IIb-B. While the decrease in fatality rate among the three groups aligned with the CAI pattern, it remains unclear whether this correlation was coincidental or if the deoptimization of codon usage in MPXV led to a reduction in fatality rates. This study sheds new light on the mechanisms that govern the evolution of MPXV in human populations.

Construction of recombinant fluorescent LSDV for high-throughput screening of antiviral drugs

Lumpy skin disease virus (LSDV) infection is a major socio-economic issue that seriously threatens the global cattle-farming industry. Here, a recombinant virus LSDV-ΔTK/EGFP, expressing enhanced green fluorescent protein (EGFP), was constructed with a homologous recombination system and applied to the high-throughput screening of antiviral drugs. LSDV-ΔTK/EGFP replicates in various kidney cell lines, consistent with wild-type LSDV. The cytopathic effect, viral particle morphology, and growth performance of LSDV-ΔTK/EGFP are consistent with those of wild-type LSDV. High-throughput screening allowed to identify several molecules that inhibit LSDV-ΔTK/EGFP replication. The strong inhibitory effect of theaflavin on LSDV was identified when 100 antiviral drugs were screened in vitro. An infection time analysis showed that theaflavin plays a role in the entry of LSDV into cells and in subsequent viral replication stages. The development of this recombinant virus will contribute to the development of LSDV-directed antiviral drugs and the study of viral replication and mechanisms of action.

Zoonotic and Zooanthroponotic Potential of Monkeypox

The current multicounty outbreak of monkeypox virus (MPXV) posed an emerging and continued challenge to already strained public healthcare sector, around the globe. Since its first identification, monkeypox disease (mpox) remained enzootic in Central and West African countries where reports of human cases are sporadically described. Recent trends in mpox spread outside the Africa have highlighted increased incidence of spillover of the MPXV from animal to humans. While nature of established animal reservoirs remained undefined, several small mammals including rodents, carnivores, lagomorphs, insectivores, non-human primates, domestic/farm animals, and several species of wildlife are proposed to be carrier of the MPXV infection. There are established records of animal-to-human (zoonotic) spread of MPXV through close interaction of humans with animals by eating bushmeat, contracting bodily fluids or trading possibly infected animals. In contrast, there are reports and increasing possibilities of human-to-animal (zooanthroponotic) spread of the MPXV through petting and close interaction with pet owners and animal care workers. We describe here the rationales and molecular factors which predispose the spread of MPXV not only amongst humans but also from animals to humans. A range of continuing opportunities for the spread and evolution of MPXV are discussed to consider risks beyond the currently identified groups. With the possibility of MPXV establishing itself in animal reservoirs, continued and broad surveillance, investigation into unconventional transmissions, and exploration of spillover events are warranted.

Differences in pathogenicity among the mpox virus clades: impact on drug discovery and vaccine development

Since May 2022, mpox virus (MPXV) has attracted considerable attention due to a multi-country outbreak. Marked differences in epidemiology, transmission, and pathology between the 2022 global mpox outbreak (clade IIb) and classical mpox disease, endemic in Africa (clades I and IIa) have been highlighted. MPXV genome analysis has identified the genomic changes characterizing clade IIb and the drivers of MPXV rapid evolution. Although mpox cases have largely declined, MPXV cryptic transmission and microevolution continues, which may lead to an MPXV of unpredictable pathogenicity. Vaccines and antivirals developed against variola virus, the agent that caused the extinguished plague smallpox, have been used to contain the 2022 mpox outbreak. In this review article, recent findings on MPXV origin and evolution and relevant models able to recapitulate differences in MPXV pathogenicity, which are important for drug and vaccine development, are discussed.

Investigation of a mpox outbreak in Central African Republic, 2021-2022

Human monkeypox virus is spreading globally, and more information is required about its epidemiological and clinical disease characteristics in endemic countries. We report the investigation of an outbreak in November 2021 in Central African Republic (CAR). The primary case, a hunter, fell ill after contact with a non-human primate at the frontier between forest and savannah. The ensuing investigation in a small nearby town concerned two families and four waves of inter-human transmission, with 14 confirmed cases, 11 suspected cases and 17 non-infected contacts, and a secondary attack rate of 59.5% (25/42). Complications were observed in 12 of the 19 (63.2%) confirmed and suspected cases with available clinical follow-up data: eight cases of bronchopneumonia, two of severe dehydration, one corneal ulcer, one abscess, two cutaneous superinfections, and six cutaneous sequelae (cheloid scars, or depigmentation). There was one death, giving a case fatality ratio of 1/25 (4.0%) for confirmed and suspected cases. This outbreak, with the largest number of confirmed cases ever described in CAR, confirms the potential severity of the disease associated with clade I monkeypox viruses, and highlights the need for rapid control over virus circulation to prevent the further national and international spread of infection.

Animal host range of mpox virus

Mpox is caused by the mpox virus, which belongs to the Orthopoxvirus genus and Poxviridae family. Animal hosts, such as African rodents, mice, prairie dogs, and non-human primates, play important roles in the development and transmission of outbreaks. Laboratory animal infection experiments have demonstrated that some animals are susceptible to mpox virus. This review summarizes the current progress on the animal hosts for mpox virus. The surveillance of mpox virus in animal hosts will provide important insights into virus tracing, analysis of mutation evolutionary patterns, transmission mechanisms, and development of control measures.

Monkeypox: Immune response, vaccination and preventive efforts

Infectious threats to humans are continuously emerging. The 2022 worldwide monkeypox outbreak is the latest of these threats with the virus rapidly spreading to 106 countries by the end of September 2022. The burden of the ongoing monkeypox outbreak is manifested by 68,000 cumulative confirmed cases and 26 deaths. Although monkeypox is usually a self-limited disease, patients can suffer from extremely painful skin lesions and complications can occur with reported mortalities. The antigenic similarity between the smallpox virus (variola virus) and monkeypox virus can be utilized to prevent monkeypox using smallpox vaccines; treatment is also based on antivirals initially designed to treat smallpox. However, further studies are needed to fully decipher the immune response to monkeypox virus and the immune evasion mechanisms. In this review we provide an up-to-date discussion of the current state of knowledge regarding monkeypox virus with a special focus on innate immune response, immune evasion mechanisms and vaccination against the virus.

Monkeypox 2022 outbreak in non-endemic countries: Open questions relevant for public health, nonpharmacological intervention and literature review

Starting from mid-May 2022, cases of human monkeypox started to rise in several non-endemic countries. By mid-July, more than 17000 confirmed/suspect cases have been reported by at least 82 countries worldwide, with a regular incremental trend. In order to contain the disease diffusion, risk evaluation is crucial to undertake informed decisions and effective communication campaigns. However, since orthopoxvirus infections so far have attracted low attention, due to the eradication of smallpox 40 years ago, and to the confinement of human monkeypox almost exclusively to endemic areas, several unresolved issues concerning natural history, ecology and pathogenesis remain. To this respect, we identified some open questions and reviewed the relevant literature on monkeypoxvirus and/or related orthopoxviruses. The results will be discussed in the perspective of their relevance to public health decisions, particularly those related to non-pharmacological interventions.

The risk of reverse zoonotic transmission to pet animals during the current global monkeypox outbreak, United Kingdom, June to mid-September 2022

We report results of surveillance between June and mid-September 2022 of pet animals living in households of confirmed human monkeypox (MPX) cases. Since surveillance commenced, 154 animals from 40 households with a confirmed human MPX case were reported to the United Kingdom Animal and Plant Health Agency. No animals with clinical signs of MPX were identified. While a risk of transmission exists to pets from owners with a confirmed MPX virus infection, we assess this risk to be low.

Monkeypox: Some Keys to Understand This Emerging Disease

In 1958, several monkeys in a Copenhagen laboratory developed a skin rash from which an orthopoxvirus could be isolated, which was named monkeypox virus (MPXV). However, the natural animal reservoir for MPXV is thought to be a rodent. The first human case occurred in 1970, and the incidence has increased progressively throughout the years. Starting May 2022, the number of cases outside Africa has soared, especially in Western Europe. There are two clades of MPXV, Congo Basin, with higher virulence and mortality, and Western Africa (WA). MPXV from the present outbreak has been proposed to be classified as Clade 3, distinct from the WA clade by at least 50 substitutions, which may increase human-to-human transmissibility. Most cases correspond to men in their 30s who have sex with men, and the possibility of sexual transmission is under investigation. Though there is no evidence of human-to-animal transmission, pets of positive human cases may be classified as low risk, including dogs, cats, and birds, who can be quarantined at home, and high risk, such as pet rabbits or mice, who should be isolated in official laboratories for observation. The current epidemiological data do not support the risk of a pandemic.