Pathogenesis of the circulating mpox virus and its adaptation to humans

Mpox primer for clinicians: what makes the difference in 2024?

PURPOSE OF REVIEW

The 2024 mpox outbreak, primarily driven by the possibly more virulent clade Ib strain, prompted the WHO declaring it a public health emergency of international concern (PHEIC) on August 14, 2024. This review provides essential guidance for clinicians managing mpox cases, as it contrasts the features of the 2024 outbreak with those of the 2022 epidemic to support better clinical decision-making.

RECENT FINDINGS

The review highlights significant differences between the 2024 and 2022 outbreaks, including total case numbers, demographic distribution, and fatality rates. It also examines the increased severity associated with clade Ib. The article reviews the differential diagnosis of mpox, diagnostic tools, updates on Tecovirimat treatment, and infection control practices, particularly among healthcare workers. Vaccination strategies, including the role of smallpox vaccines and at-risk groups, are also discussed, along with recommendations for countries outside Africa.

SUMMARY

The findings underscore the importance of early diagnosis and appropriate treatment for mpox in light of the 2024 outbreak's unique characteristics. Clinicians are advised to stay informed about updated diagnostic and therapeutic strategies, including vaccine recommendations, to mitigate the spread of the disease.

Strong and early monkeypox virus-specific immunity associated with mild disease after intradermal clade-IIb-infection in CAST/EiJ-mice

Monkeypox virus (MPXV) is a zoonotic poxvirus long endemic in West and Central Africa. Outbreaks, first the global spread of clade II outside Africa in 2022, and since 2023 the accelerating spread of clade I in central Africa, point to MPXV adaptations that pose the risk of it becoming more transmissible in humans. Animal models mimicking the clinical disease outcome in humans are important to better understand pathogenesis, host tropism, and the contribution of genetic mutations. Here, we demonstrate that MPXV infection via tail scarification in CAST/EiJ mice is an appropriate animal model to mimic human mpox. In our study, disease outcome is milder in clade IIb than clade IIa-infected mice, which is associated with enhanced immunogenicity early during infection. This suggests that clade IIb more efficiently activates host immune responses, highlighting how this animal model could facilitate studying new MPXV variants to help develop efficient antivirals and preventive measures.

Mpox Virus as a Global Public Health Emergency: A Scoping Review

The monkeypox (Mpox) virus has emerged as a global public health emergency of international concern recently. The virus that was endemic in West and Central Africa has now been reported with chains of global transmission to several countries. A scoping review was carried out from the relevant literature available from PubMed, Scopus and Web of Science. This comprehensive analysis describes the virus epidemiology, pathogenesis, clinical manifestations, complications including secondary bacterial infections, diagnosis, treatment and vaccination. The article underscores the significance of key viral and immune mediators of infection and discusses updated recommendations on therapeutic strategies and vaccination.

Comparative Analysis of 2022 Outbreak MPXV and Previous Clade II MPXV

The 2022-2024 outbreak of MPOX is an important worldwide public health issue that has triggered significant concerns in the scientific community. MPOX is caused by monkeypox virus (MPXV) belonging to the Poxviridae family. The study of MPXV presents a multifaceted challenge due to the diverse viral formThis study was supported by ISIDORe consortium and Agencia Estatal de Investigación.s produced by this pathogen. Notably the intracellular mature viruses (MVs) primarily contribute to localized lesions and host-to-host transmission, while the extracellular enveloped viruses (EVs) are associated with systemic infection. Clinically, MPOX manifests as a vesiculopustular rash that initially emerges on the face and trunk, subsequently spreading throughout the body, with heightened severity observed in immunocompromised individuals. Results obtained in this manuscript indicate that the 2022 outbreak MPXV has a significantly slower viral cycle compared with previous Clade II strains, with WRAIR 7-61 being more intermediate and USA 2003 producing highest viral titers. Additionally, proteomic and phospho-proteomic analysis displays differences in protein expression between these three strains. These findings highlight key differences between the current Lineage B.1 MPXV and previous strains. Further studies will be undertaken to demonstrate if these differences are important for the apparent increased human-to-human transmission mechanisms observed in the Clade IIb MPXV outbreak.

Insights into the emergence and evolution of monkeypox virus: Historical perspectives, epidemiology, genetic diversity, transmission, and preventative measures

In 2022, just before the COVID-19 pandemic ended, many countries noticed a viral monkeypox outbreak. Monkeypox virus, a zoonotic pathogen, causes a febrile illness in humans and resembles smallpox. Prevention strategies encompass vaccination, strict infection control measures, and avoiding contact with infected persons. As monkeypox and related poxviruses continue to pose challenges, ongoing surveillance, early diagnosis, prompt isolation, and effective control measures are crucial for limiting transmission and mitigating the impact of outbreaks on public health. This review provides valuable insights into the evolution of the monkeypox virus and its various modes of transmission, including postmortem transmission, and offers an overall perspective on the guidelines issued by the Government of India to prevent and effectively control the spread of this disease.

Modelling the impact of human behavior using a two-layer Watts-Strogatz network for transmission and control of Mpox

PURPOSE

This study aims to evaluate the effectiveness of mitigation strategies and analyze the impact of human behavior on the transmission of Mpox. The results can provide guidance to public health authorities on comprehensive prevention and control for the new Mpox virus strain in the Democratic Republic of Congo as of December 2023.

METHODS

We develop a two-layer Watts-Strogatz network model. The basic reproduction number is calculated using the next-generation matrix approach. Markov chain Monte Carlo (MCMC) optimization algorithm is used to fit Mpox cases in Canada into the network model. Numerical simulations are used to assess the impact of mitigation strategies and human behavior on the final epidemic size.

RESULTS

Our results show that the contact transmission rate of low-risk groups and susceptible humans increases when the contact transmission rate of high-risk groups and susceptible humans is controlled as the Mpox epidemic spreads. The contact transmission rate of high-risk groups after May 18, 2022, is approximately 20% lower than that before May 18, 2022. Our findings indicate a positive correlation between the basic reproduction number and the level of heterogeneity in human contacts, with the basic reproduction number estimated at 2.3475 (95% CI: 0.0749-6.9084). Reducing the average number of sexual contacts to two per week effectively reduces the reproduction number to below one.

CONCLUSION

We need to pay attention to the re-emergence of the epidemics caused by low-risk groups when an outbreak dominated by high-risk groups is under control. Numerical simulations show that reducing the average number of sexual contacts to two per week is effective in slowing down the rapid spread of the epidemic. Our findings offer guidance for the public health authorities of the Democratic Republic of Congo in developing effective mitigation strategies.

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.

Current Status of Epidemiology, Diagnosis, Therapeutics, and Vaccines for the Re-Emerging Human Monkeypox Virus

Monkeypox (Mpox) virus, a member of the Poxviridae family, causes a severe illness similar to smallpox, which is characterized by symptoms such as high fever, rash, and pustules. Human-to-human transmission cases have been reported but remained low since the first recorded case of human infection occurred in the Congo in 1970. Recently, Mpox has re-emerged, leading to an alarming surge in infections worldwide since 2022, originating in the United Kingdom. Consequently, the World Health Organization (WHO) officially declared the '2022-23 Mpox outbreak'. Currently, no specific therapy or vaccine is available for Mpox. Therefore, patients infected with Mpox are treated using conventional therapies developed for smallpox. However, the vaccines developed for smallpox have demonstrated only partial efficacy against Mpox, allowing viral transmission among humans. In this review, we discuss the current epidemiology of the ongoing Mpox outbreak and provide an update on the progress made in diagnosis, treatment, and development of vaccines for Mpox.

Overview of Diagnostic Methods, Disease Prevalence and Transmission of Mpox (Formerly Monkeypox) in Humans and Animal Reservoirs

Mpox-formerly monkeypox-is a re-emerging zoonotic virus disease, with large numbers of human cases reported during multi-country outbreaks in 2022. The close similarities in clinical symptoms that Mpox shares with many orthopoxvirus (OPXV) diseases make its diagnosis challenging, requiring laboratory testing for confirmation. This review focuses on the diagnostic methods used for Mpox detection in naturally infected humans and animal reservoirs, disease prevalence and transmission, clinical symptoms and signs, and currently known host ranges. Using specific search terms, up to 2 September 2022, we identified 104 relevant original research articles and case reports from NCBI-PubMed and Google Scholar databases for inclusion in the study. Our analyses observed that molecular identification techniques are overwhelmingly being used in current diagnoses, especially real-time PCR (3982/7059 cases; n = 41 studies) and conventional PCR (430/1830 cases; n = 30 studies) approaches being most-frequently-used to diagnose Mpox cases in humans. Additionally, detection of Mpox genomes, using qPCR and/or conventional PCR coupled to genome sequencing methods, offered both reliable detection and epidemiological analyses of evolving Mpox strains; identified the emergence and transmission of a novel clade 'hMPXV-1A' lineage B.1 during 2022 outbreaks globally. While a few current serologic assays, such as ELISA, reported on the detection of OPXV- and Mpox-specific IgG (891/2801 cases; n = 17 studies) and IgM antibodies (241/2688 cases; n = 11 studies), hemagglutination inhibition (HI) detected Mpox antibodies in human samples (88/430 cases; n = 6 studies), most other serologic and immunographic assays used were OPXV-specific. Interestingly, virus isolation (228/1259 cases; n = 24 studies), electron microscopy (216/1226 cases; n = 18 studies), and immunohistochemistry (28/40; n = 7 studies) remain useful methods of Mpox detection in humans in select instances using clinical and tissue samples. In animals, OPXV- and Mpox-DNA and antibodies were detected in various species of nonhuman primates, rodents, shrews, opossums, a dog, and a pig. With evolving transmission dynamics of Mpox, information on reliable and rapid detection methods and clinical symptoms of disease is critical for disease management.