Virulence differences of mpox (monkeypox) virus clades I, IIa, and IIb.1 in a small animal model.

Human mpox (monkeypox), a disease with similarities to smallpox, is endemic in Africa where it has persisted as a zoonosis with limited human-to-human spread. Unexpectedly, the disease expanded globally in 2022 driven by human-to-human transmission outside of Africa. It is not yet known whether the latter is due solely to behavioral and environmental factors or whether the mpox virus is adapting to a new host. Genome sequencing has revealed differences between the current outbreak strains, classified as clade IIb, and the prior clade IIa and clade I viruses, but whether these differences contribute to virulence or transmission has not been determined. We demonstrate that the wild-derived inbred castaneous mouse provides an exceptional animal model for investigating clade differences in mpox virus virulence and show that the order is clade I > clade IIa > clade IIb.1. The greatly reduced replication of the clade IIb.1 major outbreak strain in mice and absence of lethality at 100 times the lethal dose of a closely related clade IIa virus, despite similar multiplication in cell culture, suggest that clade IIb is evolving diminished virulence or adapting to other species.

Prolonged Mpox Disease in People With Advanced HIV: Characterization of Mpox Skin Lesions.

We report 3 complicated and prolonged cases of mpox in people with advanced human immunodeficiency virus (HIV) not on antiretroviral therapy (ART) at mpox diagnosis. Multiple medical countermeasures were used, including prolonged tecovirimat treatment and immune optimization with ART initiation. Immunofluorescence of skin biopsies demonstrated a dense immune infiltrate of predominantly myeloid and CD8+ T cells, with a strong type I interferon local response. RNAscope detected abundant replication of monkeypox virus (MPXV) in epithelial cells and dendritic cells. These data suggest that prolonged mpox in people with advanced HIV may be due to ongoing MPXV replication, warranting aggressive medical countermeasures and immune optimization.

Orthopoxvirus-Specific T-Cell Responses in Convalescent Mpox Patients.

Orthopoxvirus-specific T-cell responses were analyzed in 10 patients who had recovered from Mpox including 7 people with human immunodeficiency virus (PWH). Eight participants had detectable virus-specific T-cell responses, including a PWH who was not on antiretroviral therapy and a PWH on immunosuppressive therapy. These 2 participants had robust polyfunctional CD4+ T-cell responses to peptides from the 121L vaccinia virus (VACV) protein. T-cells from 4 of 5 HLA-A2-positive participants targeted at least 1 previously described HLA-A2-restricted VACV epitope, including an epitope targeted in 2 participants. These results advance our understanding of immunity in convalescent Mpox patients.

Variola Virus and Clade I Mpox Virus Differentially Modulate Cellular Responses Longitudinally in Monocytes During Infection.

Variola virus (VARV), the etiological agent of smallpox, had enormous impacts on global health prior to its eradication. In the absence of global vaccination programs, mpox virus (MPXV) has become a growing public health threat that includes endemic and nonendemic regions across the globe. While human mpox resembles smallpox in clinical presentation, there are considerable knowledge gaps regarding conserved molecular pathogenesis between these 2 orthopoxviruses. Thus, we sought to compare MPXV and VARV infections in human monocytes through kinome analysis. We performed a longitudinal analysis of host cellular responses to VARV infection in human monocytes as well as a comparative analysis to clade I MPXV-mediated responses. While both viruses elicited strong activation of cell responses early during infection as compared to later time points, several key differences in cell signaling events were identified and validated. These observations will help in the design and development of panorthopoxvirus therapeutics.

Retrospective Seroprevalence of Orthopoxvirus Antibodies among Key Populations, Kenya.

We identified a cluster of mpox exposures among key populations in Kenya through retrospective serologic screening. We identified strong seropositivity among sex workers and gay, bisexual, and other men who have sex with men. These findings demonstrate the need for increased mpox surveillance among mpox-endemic and mpox-endemic-adjacent regions in Africa.

One Health Investigation into Mpox and Pets, United States.

Monkeypox virus (MPXV) is zoonotic and capable of infecting many mammal species. However, whether common companion animals are susceptible to MPXV infection is unclear. During July 2022-March 2023, we collected animal and environmental swab samples within homes of confirmed human mpox case-patients and tested for MPXV and human DNA by PCR. We also used ELISA for orthopoxvirus antibody detection. Overall, 12% (22/191) of animal and 25% (14/56) of environmental swab samples from 4 households, including samples from 4 dogs and 1 cat, were positive for MPXV DNA, but we did not detect viable MPXV or orthopoxvirus antibodies. Among MPXV PCR-positive swab samples, 82% from animals and 93% from environment amplified human DNA with a statistically significant correlation in observed cycle threshold values. Our findings demonstrate likely DNA contamination from the human mpox cases. Despite the high likelihood for exposure, we found no indications that companion animals were infected with MPXV.

Co-Circulating Monkeypox and Swinepox Viruses, Democratic Republic of the Congo, 2022.

In September 2022, deaths of pigs manifesting pox-like lesions caused by swinepox virus were reported in Tshuapa Province, Democratic Republic of the Congo. Two human mpox cases were found concurrently in the surrounding community. Specific diagnostics and robust sequencing are needed to characterize multiple poxviruses and prevent potential poxvirus transmission.

Differential diagnosis of exanthematous viruses during the 2022 Mpox outbreak in Minas Gerais, Brazil.

The monkeypox virus (MPXV) outbreak, primarily endemic to Africa, has spread globally, with Brazil reporting the second-highest number of cases. The emergence of MPXV in non-endemic areas has raised concerns, particularly due to the co-circulation of other exanthematous viruses such as varicella-zoster virus (VZV) and molluscum contagiosum virus (MOCV). To perform an accurate differential diagnosis of MPXV during the ongoing outbreak in Minas Gerais, Brazil, a 5PLEX qPCR assay targeting orthopoxviruses (OPV), VZV, and MOCV was used to retrospectively analyze all clinical samples that tested negative for MPXV in the initial screening conducted at Funed. In summary, our study analyzed 1,175 clinical samples received from patients suspected of MPXV infection and found a positivity rate of 33.8% (397 samples) for MPXV using the non-variola qPCR assay. Testing the 778 MPXV-negative clinical samples using the 5PLEX qPCR assay revealed that 174 clinical samples (22.36%) tested positive for VZV. MOCV DNA was detected in 13 and other OPV in 3 clinical samples. The sequencing of randomly selected amplified clinical samples confirmed the initial molecular diagnosis. Analysis of patient profiles revealed a significant difference in the median age between groups testing positive for MPXV and VZV and a male predominance in MPXV cases. The geographic distribution of positive cases was concentrated in the most populous mesoregions of Minas Gerais state. This study highlights the challenges posed by emerging infectious diseases. It emphasizes the importance of epidemiological surveillance and accurate diagnosis in enabling timely responses for public health policies and appropriate medical care. IMPORTANCE: Brazil ranks second in the number of cases during the global monkeypox epidemic. The study, conducted in Minas Gerais, the second most populous state in Brazil with over 20 million inhabitants, utilized differential diagnostics, revealing a significant number of positive cases for other exanthematous viruses and emphasizing the need for accurate diagnoses. During the study, we were able to assess the co-circulation of other viruses alongside monkeypox, including varicella-zoster virus, molluscum contagiosum virus, and other orthopoxviruses. The significance of the research is underscored by the concentration of positive cases in populous areas, highlighting the challenges posed by emerging infectious diseases. This demographic context further amplifies the importance of the research in guiding public health policies and medical interventions, given the substantial population at risk. The study not only addresses a global concern but also holds critical implications for a state with such a large population and geographic expanse within Brazil. Overall, the study emphasizes the pivotal role of surveillance and precise diagnosis in guiding effective public health responses and ensuring appropriate medical interventions.

Monkeypox (Mpox) vs. Innate immune responses: Insights into evasion mechanisms and potential therapeutic strategies.

Orthopoxviruses, a group of zoonotic viral infections, have emerged as a significant health emergency and global concern, particularly exemplified by the re-emergence of monkeypox (Mpox). Effectively addressing these viral infections necessitates a comprehensive understanding of the intricate interplay between the viruses and the host's immune response. In this review, we aim to elucidate the multifaceted aspects of innate immunity in the context of orthopoxviruses, with a specific focus on monkeypox virus (MPXV). We provide an in-depth analysis of the roles of key innate immune cells, including natural killer (NK) cells, dendritic cells (DCs), and granulocytes, in the host defense against MPXV. Furthermore, we explore the interferon (IFN) response, highlighting the involvement of toll-like receptors (TLRs) and cytosolic DNA/RNA sensors in detecting and responding to the viral presence. This review also examines the complement system's contribution to the immune response and provides a detailed analysis of the immune evasion strategies employed by MPXV to evade host defenses. Additionally, we discuss current prevention and treatment strategies for Mpox, including pre-exposure (PrEP) and post-exposure (PoEP) prophylaxis, supportive treatments, antivirals, and vaccinia immune globulin (VIG).

Risk profile and mode of transmission of Mpox: A rapid review and individual patient data meta-analysis of case studies.

Since May 2022, an outbreak of Mpox in non-endemic countries has become a potential public health threat. The objective of this rapid review was to examine the risk profile and modes of transmission of Mpox. PubMed, Web of Science, and Scopus were searched from inception through July 30 to collect case reports/series on patients with Mpox infection. For meta-analysis, data on the total number of participants and deaths by binary categories of exposure (age, sex, country, other co-infections or existing conditions, and mode of contagion) were used. A total of 62 studies (4659 cases) were included. Most cases came from Africa (84.3%), followed by Europe (13.9%). In 63.6% of the cases, the mode of contagion was human contact, while 22.8% of the cases were by animal contact, and 13.5% were unknown or not reported. The mortality rate was 6.5% throughout these studies. The risk of mortality was higher in the younger age group (risk difference: 0.19; 95% CI: 0.02-0.36), in cases with other co-infections or current chronic conditions (risk difference: 0.03; 95% CI: 0.01-0.05) and in the category of low- and middle-income countries (risk difference: 0.06; 95% CI: 0.05-0.08). There were no significant differences with respect to sex or mode of contagion. These results help to understand the major infection pathways and mortality risk profiles of Mpox and underscores the importance of preventing outbreaks in specific settings, especially in settings densely populated by children, such as day care centres and schools.

Poxviruses from the Concept of One Health.

In the last 4 years, the world has experienced two pandemics of bat-borne viruses. Firstly, in 2019 the SARS-CoV-2 pandemic started and has been causing millions of deaths around the world. In 2022, a Monkeypox pandemic rose in various countries of the world. Those pandemics have witnessed movements and initiatives from healthcare and research institutions to establish a worldwide understanding to battle any future pandemics and biological threats. One Health concept is a modern, comprehensive, unifying ways to improve humans, animals, and ecosystems' health. This concept shows how much they are intertwined and related to one another, whether it is an environmental, or a pathological relation. This review aims to describe Poxviridae and its impact on the One Health concept, by studying the underlying causes of how poxviruses can affect the health of animals, humans, and environments. Reviewing the effect of disease transmission between animal to human, human to human, and animal to animal with pox viruses as a third party to achieve a total understanding of infection and viral transmission. Thus, contributing to enhance detection, diagnosis, research, and treatments regarding the application of One Health.

Biological Characteristics and Pathogenesis of Monkeypox Virus: An Overview.

Although the smallpox virus has been eradicated worldwide, the World Health Organization (WHO) has issued a warning about the virus's potential to propagate globally. The WHO labeled monkeypox a world public health emergency in July 2022, requiring urgent prevention and treatment. The monkeypox virus is a part of the Poxviridae family, Orthopoxvirus genus, and is accountable for smallpox, which has killed over a million people in the past. Natural hosts of the virus include squirrels, Gambian rodents, chimpanzees, and other monkeys. The monkeypox virus has transmitted to humans through primary vectors (various animal species) and secondary vectors, including direct touch with lesions, breathing particles from body fluids, and infected bedding. The viral particles are ovoid or brick-shaped, 200-250 nm in diameter, contain a single double-stranded DNA molecule, and reproduce only in the cytoplasm of infected cells. Monkeypox causes fever, cold, muscle pains, headache, fatigue, and backache. The phylogenetic investigation distinguished between two genetic clades of monkeypox: the more pathogenic Congo Basin clade and the West Africa clade. In recent years, the geographical spread of the human monkeypox virus has accelerated despite a paucity of information regarding the disease's emergence, ecology, and epidemiology. Using lesion samples and polymerase chain reaction (PCR), the monkeypox virus was diagnosed. In the USA, the improved Ankara vaccine can now be used to protect people who are at a higher risk of getting monkeypox. Antivirals that we have now work well against smallpox and may stop the spread of monkeypox, but there is no particular therapy for monkeypox.

Continued circulation of mpox: an epidemiological and phylogenetic assessment, European Region, 2023 to 2024.

During the summer of 2023, the European Region experienced a limited resurgence of mpox cases following the substantial outbreak in 2022. This increase was characterised by asynchronous and bimodal increases, with countries experiencing peaks at different times. The demographic profile of cases during the resurgence was largely consistent with those reported previously. All available sequences from the European Region belonged to clade IIb. Sustained efforts are crucial to control and eventually eliminate mpox in the European Region.

Orthopoxvirus-specific antibodies wane to undetectable levels 1 year after MVA-BN vaccination of at-risk individuals, the Netherlands, 2022 to 2023.

In response to the mpox outbreak in 2022 and 2023, widespread vaccination with modified vaccinia Ankara-Bavarian Nordic (MVA-BN, also known as JYNNEOS or Imvanex) was initiated. Here, we demonstrate that orthopoxvirus-specific binding and MVA-neutralising antibodies waned to undetectable levels 1 year post vaccination in at-risk individuals who received two doses of MVA-BN administered subcutaneously with an interval of 4 weeks, without prior smallpox or mpox vaccination. Continuous surveillance is essential to understand the impact of declining antibody levels.

Human monkeypox: An updated appraisal on epidemiology, evolution, pathogenesis, clinical manifestations, and treatment strategies.

Monkeypox (Mpox) is a zoonotic viral disease caused by the monkeypox virus (MPXV), a member of the Orthopoxvirus genus. The recent occurrence of Mpox infections has become a significant global issue in recent months. Despite being an old disease with a low mortality rate, the ongoing multicountry outbreak is atypical due to its occurrence in nonendemic countries. The current review encompasses a comprehensive analysis of the literature pertaining to MPXV, with the aim of consolidating the existing data on the virus's epidemiological, biological, and clinical characteristics, as well as vaccination and treatment regimens against the virus.

Monkeypox Virus Infections in Humans.

Human monkeypox is a viral zoonosis endemic to West and Central Africa that has recently generated increased interest and concern on a global scale as an emerging infectious disease threat in the midst of the slowly relenting COVID-2019 disease pandemic. The hallmark of infection is the development of a flu-like prodrome followed by the appearance of a smallpox-like exanthem. Precipitous person-to-person transmission of the virus among residents of 100 countries where it is nonendemic has motivated the immediate and widespread implementation of public health countermeasures. In this review, we discuss the origins and virology of monkeypox virus, its link with smallpox eradication, its record of causing outbreaks of human disease in regions where it is endemic in wildlife, its association with outbreaks in areas where it is nonendemic, the clinical manifestations of disease, laboratory diagnostic methods, case management, public health interventions, and future directions.

Potential Anti-Mpox Virus Activity of Atovaquone, Mefloquine, and Molnupiravir, and Their Potential Use as Treatments.

BACKGROUND: Mpox virus (MPXV) is a zoonotic orthopoxvirus and caused an outbreak in 2022. Although tecovirimat and brincidofovir are approved as anti-smallpox drugs, their effects in mpox patients have not been well documented. In this study, by a drug repurposing approach, we identified potential drug candidates for treating mpox and predicted their clinical impacts by mathematical modeling. METHODS: We screened 132 approved drugs using an MPXV infection cell system. We quantified antiviral activities of potential drug candidates by measuring intracellular viral DNA and analyzed the modes of action by time-of-addition assay and electron microscopic analysis. We further predicted the efficacy of drugs under clinical concentrations by mathematical simulation and examined combination treatment. RESULTS: Atovaquone, mefloquine, and molnupiravir exhibited anti-MPXV activity, with 50% inhibitory concentrations of 0.51-5.2 µM, which was more potent than cidofovir. Whereas mefloquine was suggested to inhibit viral entry, atovaquone and molnupiravir targeted postentry processes. Atovaquone was suggested to exert its activity through inhibiting dihydroorotate dehydrogenase. Combining atovaquone with tecovirimat enhanced the anti-MPXV effect of tecovirimat. Quantitative mathematical simulations predicted that atovaquone can promote viral clearance in patients by 7 days at clinically relevant drug concentrations. CONCLUSIONS: These data suggest that atovaquone would be a potential candidate for treating mpox.

Geographic Structuring and Divergence Time Frame of Monkeypox Virus in the Endemic Region.

BACKGROUND: Monkeypox is an emerging zoonosis endemic to Central and West Africa. Monkeypox virus (MPXV) is genetically structured in 2 major clades (clades 1 and 2/3), but its evolution is poorly explored. METHODS: We retrieved MPXV genomes from public repositories and we analyzed geographic patterns using STRUCTURE. Molecular dating was performed using a using a Bayesian approach. RESULTS: We show that the population transmitted in West Africa (clades 2/3) experienced limited drift. Conversely, clade 1 (transmitted in the Congo Basin) possibly underwent a bottleneck or founder effect. Depending on the model used, we estimated that the 2 clades separated ∼560-860 (highest posterior density: 450-960) years ago, a period characterized by expansions and contractions of rainforest areas, possibly creating the ecological conditions for the MPXV reservoir(s) to migrate. In the Congo Basin, MPXV diversity is characterized by 4 subpopulations that show no geographic structuring. Conversely, clades 2/3 are spatially structured with 2 populations located West and East of the Dahomey Gap. CONCLUSIONS: The distinct histories of the 2 clades may derive from differences in MPXV ecology in West and Central Africa.

One- and Two-Dose Vaccinations With Modified Vaccinia Ankara-Bavarian Nordic Induce Durable B-Cell Memory Responses Comparable to Replicating Smallpox Vaccines.

BACKGROUND: Although modified vaccinia Ankara-Bavarian Nordic (MVA-BN) vaccination is approved for smallpox and monkeypox prevention, immunological persistence and booster effects remain undescribed. METHODS: Participants naive to smallpox vaccination were randomized to 1 dose MVA-BN (1×MVA, n = 181), 2 doses MVA-BN (2×MVA, n = 183), or placebo (n = 181). Participants with previous smallpox vaccination received 1 MVA-BN booster (HSPX, n = 200). Subsets of the formerly naive groups (approximately 75 each) received an MVA-BN booster 2 years later. RESULTS: Neutralizing antibody (nAb) geometric mean titers (GMTs) increased from 1.1 (baseline, both naive groups) to 7.2 and 7.5 (week 4, 1×MVA and 2×MVA, respectively), and further to 45.6 (week 6, 2×MVA after second vaccination). In HSPX, nAb GMT rapidly increased from 21.6 (baseline) to 175.1 (week 2). At 2 years, GMTs for 1×MVA, 2×MVA, and HSPX were 1.1, 1.3, and 10.3, respectively. After boosting in the previously naive groups, nAb GMTs increased rapidly in 2 weeks to 80.7 (1×MVA) and 125.3 (2×MVA), higher than after primary vaccination and comparable to boosted HSPX subjects. Six months after boosting, GMTs were 25.6 (1×MVA) and 49.3 (2×MVA). No safety concerns were identified. CONCLUSIONS: Anamnestic responses to boosting without sustained high nAb titers support presence of durable immunological memory following primary MVA-BN immunization. Clinical Trials Registration. NCT00316524 and NCT00686582.

Prevalence of Undiagnosed Monkeypox Virus Infections during Global Mpox Outbreak, United States, June-September 2022.

Since May 2022, mpox has been identified in 108 countries without endemic disease; most cases have been in gay, bisexual, or other men who have sex with men. To determine number of missed cases, we conducted 2 studies during June-September 2022: a prospective serologic survey detecting orthopoxvirus antibodies among men who have sex with men in San Francisco, California, and a retrospective monkeypox virus PCR testing of swab specimens submitted for other infectious disease testing among all patients across the United States. The serosurvey of 225 participants (median age 34 years) detected 18 (8.0%) who were orthopoxvirus IgG positive and 3 (1.3%) who were also orthopoxvirus IgM positive. The retrospective PCR study of 1,196 patients (median age 30 years; 54.8% male) detected 67 (5.6%) specimens positive for monkeypox virus. There are likely few undiagnosed cases of mpox in regions where sexual healthcare is accessible and patient and clinician awareness about mpox is increased.