Cross-Neutralizing and Protective Human Antibody Specificities to Poxvirus Infections.

Monkeypox (MPXV) and cowpox (CPXV) are emerging agents that cause severe human infections on an intermittent basis, and variola virus (VARV) has potential for use as an agent of bioterror. Vaccinia immune globulin (VIG) has been used therapeutically to treat severe orthopoxvirus infections but is in short supply. We generated a large panel of orthopoxvirus-specific human monoclonal antibodies (Abs) from immune subjects to investigate the molecular basis of broadly neutralizing antibody responses for diverse orthopoxviruses. Detailed analysis revealed the principal neutralizing antibody specificities that are cross-reactive for VACV, CPXV, MPXV, and VARV and that are determinants of protection in murine challenge models. Optimal protection following respiratory or systemic infection required a mixture of Abs that targeted several membrane proteins, including proteins on enveloped and mature virion forms of virus. This work reveals orthopoxvirus targets for human Abs that mediate cross-protective immunity and identifies new candidate Ab therapeutic mixtures to replace VIG.

Smallpox lesion characterization in placebo-treated and tecovirimat-treated macaques using traditional and novel methods.

Smallpox was the most rampant infectious disease killer of the 20th century, yet much remains unknown about the pathogenesis of the variola virus. Using archived tissue from a study conducted at the Centers for Disease Control and Prevention we characterized pathology in 18 cynomolgus macaques intravenously infected with the Harper strain of variola virus. Six macaques were placebo-treated controls, six were tecovirimat-treated beginning at 2 days post-infection, and six were tecovirimat-treated beginning at 4 days post-infection. All macaques were treated daily until day 17. Archived tissues were interrogated using immunohistochemistry, in situ hybridization, immunofluorescence, and electron microscopy. Gross lesions in three placebo-treated animals that succumbed to infection primarily consisted of cutaneous vesicles, pustules, or crusts with lymphadenopathy. The only gross lesions noted at the conclusion of the study in the three surviving placebo-treated and the Day 4 treated animals consisted of resolving cutaneous pox lesions. No gross lesions attributable to poxviral infection were present in the Day 2 treated macaques. Histologic lesions in three placebo-treated macaques that succumbed to infection consisted of proliferative and necrotizing dermatitis with intracytoplasmic inclusion bodies and lymphoid depletion. The only notable histologic lesion in the Day 4 treated macaques was resolving dermatitis; no notable lesions were seen in the Day 2 treated macaques. Variola virus was detected in all three placebo-treated animals that succumbed to infection prior to the study's conclusion by all utilized methods (IHC, ISH, IFA, EM). None of the three placebo-treated animals that survived to the end of the study nor the animals in the two tecovirimat treatment groups showed evidence of variola virus by these methods. Our findings further characterize variola lesions in the macaque model and describe new molecular methods for variola detection.

Human FAM111A inhibits vaccinia virus replication by degrading viral protein I3 and is antagonized by poxvirus host range factor SPI-1.

Zoonotic poxviruses such as mpox virus (MPXV) continue to threaten public health safety since the eradication of smallpox. Vaccinia virus (VACV), the prototypic poxvirus used as the vaccine strain for smallpox eradication, is the best-characterized member of the poxvirus family. VACV encodes a serine protease inhibitor 1 (SPI-1) conserved in all orthopoxviruses, which has been recognized as a host range factor for modified VACV Ankara (MVA), an approved smallpox vaccine and a promising vaccine vector. FAM111A (family with sequence similarity 111 member A), a nuclear protein that regulates host DNA replication, was shown to restrict the replication of a VACV SPI-1 deletion mutant (VACV-ΔSPI-1) in human cells. Nevertheless, the detailed antiviral mechanisms of FAM111A were unresolved. Here, we show that FAM111A is a potent restriction factor for VACV-ΔSPI-1 and MVA. Deletion of FAM111A rescued the replication of MVA and VACV-ΔSPI-1 and overexpression of FAM111A significantly reduced viral DNA replication and virus titers but did not affect viral early gene expression. The antiviral effect of FAM111A necessitated its trypsin-like protease domain and DNA-binding domain but not the PCNA-interacting motif. We further identified that FAM111A translocated into the cytoplasm upon VACV infection by degrading the nuclear pore complex via its protease activity, interacted with VACV DNA-binding protein I3, and promoted I3 degradation through autophagy. Moreover, SPI-1 from VACV, MPXV, or lumpy skin disease virus was able to antagonize FAM111A by prohibiting its nuclear export. Our findings reveal the detailed mechanism by which FAM111A inhibits VACV and provide explanations for the immune evasive function of VACV SPI-1.

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.

Residual Immunity from Smallpox Vaccination and Possible Protection from Mpox, China.

Among persons born in China before 1980 and tested for vaccinia virus Tiantan strain (VVT), 28.7% (137/478) had neutralizing antibodies, 71.4% (25/35) had memory B-cell responses, and 65.7% (23/35) had memory T-cell responses to VVT. Because of cross-immunity between the viruses, these findings can help guide mpox vaccination strategies in China.

Smallpox vaccination campaigns resulted in age-associated population cross-immunity against monkeypox virus.

Increased human-to-human transmission of monkeypox virus (MPXV) is cause for concern, and antibodies directed against vaccinia virus (VACV) are known to confer cross-protection against Mpox. We used 430 serum samples derived from the Scottish patient population to investigate antibody-mediated cross-neutralization against MPXV. By combining electrochemiluminescence immunoassays with live-virus neutralization assays, we show that people born when smallpox vaccination was routinely offered in the United Kingdom have increased levels of antibodies that cross-neutralize MPXV. Our results suggest that age is a risk factor of Mpox infection, and people born after 1971 are at higher risk of infection upon exposure.

Mpox neglect and the smallpox niche: a problem for Africa, a problem for the world.

Mpox (formerly known as monkeypox) is a zoonotic viral disease endemic in parts of Africa. In May, 2022, the world was alerted to circulation of monkeypox virus in many high-income countries outside of Africa. Continued spread resulted in a WHO declaration of a Public Health Emergency of International Concern. Although there has been much attention on the global outbreak, most of the focus has been on high-income countries outside of Africa, despite the fact that monkeypox virus has been causing disease in parts of Africa for at least 50 years. Furthermore, the long-term consequences of this event, especially the risk that mpox fills the niche vacated through smallpox eradication, have not been sufficiently considered. The heart of the problem is the historical neglect of mpox in Africa where the disease is endemic, and the actual and potential consequences if this neglect is left uncorrected.

Smallpox vaccination induces a substantial increase in commensal skin bacteria that promote pathology and influence the host response.

Interactions between pathogens, host microbiota and the immune system influence many physiological and pathological processes. In the 20th century, widespread dermal vaccination with vaccinia virus (VACV) led to the eradication of smallpox but how VACV interacts with the microbiota and whether this influences the efficacy of vaccination are largely unknown. Here we report that intradermal vaccination with VACV induces a large increase in the number of commensal bacteria in infected tissue, which enhance recruitment of inflammatory cells, promote tissue damage and influence the host response. Treatment of vaccinated specific-pathogen-free (SPF) mice with antibiotic, or infection of genetically-matched germ-free (GF) animals caused smaller lesions without alteration in virus titre. Tissue damage correlated with enhanced neutrophil and T cell infiltration and levels of pro-inflammatory tissue cytokines and chemokines. One month after vaccination, GF and both groups of SPF mice had equal numbers of VACV-specific CD8+ T cells and were protected from disease induced by VACV challenge, despite lower levels of VACV-neutralising antibodies observed in GF animals. Thus, skin microbiota may provide an adjuvant-like stimulus during vaccination with VACV and influence the host response to vaccination.

Evaluation of monkeypox- and vaccinia-virus neutralizing antibodies before and after smallpox vaccination: A sero-epidemiological study.

Since May 2022, several countries outside of Africa experienced multiple clusters of monkeypox virus (MPXV)-associated disease. In the present study, anti-MPXV and anti-vaccinia virus (VACV) neutralizing antibody responses were evaluated in two cohorts of subjects from the general Italian population (one half born before the WHO-recommended end of smallpox vaccination in 1980, the other half born after). Higher titers (either against MPXV or VACV) were observed in the cohort of individuals born before the interruption of VACV vaccination. An association between VACV and MPXV antibody levels was observed, suggesting that the smallpox vaccination may confer some degree of cross-protection against MPXV infection. Results from this study highlight low levels of immunity toward the assessed Orthopoxviruses, especially in young adults, advocating the introduction of a VACV- or MPXV-specific vaccine in case of resurgence of monkeypox disease outbreaks.

Tracing the journey of poxviruses: insights from history.

The historical significance of the poxviruses is profound, largely due to the enduring impact left by smallpox virus across many centuries. The elimination of smallpox is a remarkable accomplishment in the history of science and medicine, with centuries of devoted efforts resulting in the development and widespread administration of smallpox vaccines. This review provides insight into the pivotal historical events involving medically significant poxviruses. Understanding the remarkable saga of combatting smallpox is crucial, serving as a guidepost for potential future encounters with poxvirus infections. There is a continual need for vigilant observation of poxvirus evolution and spillover from animals to humans, considering the expansive range of susceptible hosts. The recent occurrence of monkeypox cases in non-endemic countries stands as a stark reminder of the ease with which infections can be disseminated through international travel and trade. This backdrop encourages introspection about our journey and the current status of poxvirus research.

Effect of prior immunisation with smallpox vaccine for protection against human Mpox: A systematic review.

Monkeypox is an emerging threat to humans since a new outbreak in May 2022. It is hypothesised that increasing the immunologically naive population after the cessation of the smallpox vaccination campaign in the 1980s is one of the leading causes of it. A literature search was conducted using different electronic databases including MEDLINE (through PubMed), SCOPUS, Web of Science, Cochrane library, and EMBASE for relevant studies. After duplication removal, abstract and title screening, and full-text screening were done, the data were extracted, tabulated, and analysed. The risk of bias was assessed following the Risk of Bias Assessment tool for Non-randomised Studies. We found a total of 1068 relevant articles and finally, we included 6 articles including 2083 participants. The studies suggested that smallpox is 80.7% efficacious to prevent human monkeypox and the immunity provided by prior smallpox vaccination is long-lasting. Moreover, the smallpox vaccination decreases the risk of human monkeypox by 5.2-folds. Two cross-sectional studies based on the Democratic Republic of the Congo (DRC) including a total of around 1800 monkeypox cases found that unvaccinated participants had 2.73 and 9.64-fold increased risk of monkeypox compared to the vaccinated participants. Other studies in USA and Spain also demonstrated that unvaccinated people were more prone to develop monkeypox than vaccinated people. Furthermore, monkeypox incidence has increased by 20 folds, 30 years after the cessation of the smallpox vaccination campaign in DRC. Evidence-based preventive and therapeutic agents are still not available for human monkeypox. Further study should be done to explore the role of the smallpox vaccine in preventing human monkeypox.

Global polio eradication; can we replicate the smallpox success story?

Although the Global Polio Eradication Initiative has been largely successful in elimination of polio from various parts of the world, sporadic local outbreaks in non-endemic areas continue to pose a threat to global polio eradication efforts. In the two endemic countries, Pakistan and Afghanistan, a staggering 176 cases of wild poliovirus 1 (WPV1) were reported in 2019. In 2020 alone, 959 cases of Circulating Vaccine Derived Poliovirus 2 were reported globally from 27 countries. After staying polio-free for years, cases of WPV were detected in Malawi and Mozambique in 2022. The roots of the reported strains matched with the WPV strain from Pakistan. The emergence of WPV cases in Malawi and Mozambique underscores the fact that WPV still has the chance to spread beyond the Afghanistan-Pakistan region and sustained efforts are required for its complete eradication. In the case of smallpox, surveillance-containment was the key to eradication as many countries had already eradicated smallpox and the bigger concern was to track and contain any new cases emerging. Smallpox eradication followed a comprehensive plan which included elements like quality control and standardisation of vaccination protocols. Governments all over the world should prioritise immunisation drives, surveillance, and awareness campaigns to achieve the dream of a polio-free world.

An overview on mRNA-based vaccines to prevent monkeypox infection.

The human monkeypox virus (Mpox) is classified as a member of the Poxviridae family and belongs to the Orthopoxvirus genus. Mpox possesses double-stranded DNA, and there are two known genetic clades: those originating in West Africa and the Congo Basin, commonly known as Central African clades. Mpox may be treated with either the vaccinia vaccination or the therapeutics. Modifying the smallpox vaccine for treating and preventing Mpox has shown to be beneficial because of the strong link between smallpox and Mpox viruses and their categorization in the same family. Cross-protection against Mpox is effective with two Food and Drug Administration (FDA)-approved smallpox vaccines (ACAM2000 and JYNNEOSTM). However, ACAM2000 has the potential for significant adverse effects, such as cardiac issues, whereas JYNNEOS has a lower risk profile. Moreover, Mpox has managed to resurface, although with modified characteristics, due to the discontinuation and cessation of the smallpox vaccine for 40 years. The safety and efficacy of the two leading mRNA vaccines against SARS-CoV-2 and its many variants have been shown in clinical trials and subsequent data analysis. This first mRNA treatment model involves injecting patients with messenger RNA to produce target proteins and elicit an immunological response. High potency, the possibility of safe administration, low-cost manufacture, and quick development is just a few of the benefits of RNA-based vaccines that pave the way for a viable alternative to conventional vaccines. When protecting against Mpox infection, mRNA vaccines are pretty efficient and may one day replace the present whole-virus vaccines. Therefore, the purpose of this article is to provide a synopsis of the ongoing research, development, and testing of an mRNA vaccine against Mpox.

Biology of Variola Virus.

Variola virus is an anthroponotic agent that belongs to the orthopoxvirus family. It is an etiological agent of smallpox, an ancient disease that caused massive mortality of human populations. Twentieth century has witnessed the death of about 300 million people due to the unavailability of an effective vaccine. Early detection is the primary strategy to prevent an outbreak of smallpox. Variola virus forms the characteristic pus-filled pustules and centrifugal rash distribution in the infected patients while transmission occurs mainly through respiratory droplets during the early stage of infection. No antiviral drugs are approved for variola virus till date. Generation of first-generation vaccines helped in the eradication of smallpox which was declared by the World Health Organization.

Role of the Laboratory in the Diagnosis of Poxvirus Infections.

Although WHO-led global efforts led to eradication of smallpox over four decades ago, other poxviruses, especially monkeypox, have re-emerged to occupy the ecological niche vacated by smallpox. Many of these viruses produce similar lesions thus mandating a prompt laboratory confirmation. There has been considerable evolution in the techniques available to diagnose these infections and differentiate between them. With the 2022 multi-country outbreak of monkeypox, significant efforts were made to apprise the laboratory diagnosis of the virus and numerous real-time-PCR-based assays were made commercially available. This chapter discusses the sample collection and biosafety aspects along with the repertoire of diagnostic modalities, both traditional and emerging, for poxviruses which a special focus on monkeypox. The advantages and disadvantages of each technique have been illustrated. We have also reflected upon the newer advances and the existing lacunae.

Poxvirus Vaccines: Past, Present, and Future.

Smallpox was a significant cause of mortality for over three thousand years, amounting to 10% of deaths yearly. Edward Jenner discovered smallpox vaccination in 1796, which rapidly became a smallpox infection preventive practice throughout the world and eradicated smallpox infection by 1980. After smallpox eradication, monkeypox vaccines have been used primarily in research and in outbreaks in Africa, where the disease is endemic. In the present, the vaccines are being used for people who work with animals or in high-risk areas, as well as for healthcare workers treating patients with monkeypox. Among all orthopoxviruses (OPXV), monkeypox viral (MPXV) infection occurs mainly in cynomolgus monkeys, natural reservoirs, and occasionally causes severe multi-organ infection in humans, who were the incidental hosts. The first case of the present epidemic of MXPV was identified on May 7, 2022, and rapidly increased the number of cases. In this regard, the WHO declared the outbreak, an international public health emergency on July 23, 2022. The first monkeypox vaccine was developed in the 1960s by the US Army and was based on the vaccinia virus, which is also used in smallpox vaccines. In recent years, newer monkeypox vaccines have been developed based on other viruses such as Modified Vaccinia Ankara (MVA). These newer vaccines are safer and can provide longer-lasting immunity with fewer side effects. For the future, there is ongoing research to improve the current vaccines and to develop new ones. One notable advance has been the development of a recombinant vaccine that uses a genetically modified vaccinia virus to express monkeypox antigens. This vaccine has shown promising results in pre-clinical trials and is currently undergoing further testing in clinical trials. Another recent development has been the use of a DNA vaccine, which delivers genetic material encoding monkeypox antigens directly into cells. This type of vaccine has shown effectiveness in animal studies and is also undergoing clinical testing in humans. Overall, these recent advances in monkeypox vaccine development hold promise for protecting individuals against this potentially serious disease.

Poxviruses as Agents of Biological Warfare: The Importance of Ensuring Ethical Standards for Research with Viruses.

Historically, biological agents have been used to target various populations. One of the earliest examples could be the catastrophic effect of smallpox in Australia in the eighteenth century (as alleged by some historians). Modern biological techniques can be used to both create or provide protection against various agents of biological warfare. Any microorganism (viruses, bacteria, and fungi) or its toxins can be used as biological agents. Minnesota Department of Health has listed Smallpox (variola major) as a category A bioterrorism agent, even though it has been eradicated in 1980 through an extensive vaccination campaign. Category A agents are considered the highest risk to public health. Laboratory-associated outbreaks of poxviruses could cause unprecedented occupational hazards. Only two WHO-approved BSL-4 facilities in the United States and Russia are allowed to perform research on the variola virus. So, poxviruses present themselves as a classical case of a dual-use dilemma, since research with them can be used for both beneficial and harmful purposes. Although the importance of ethics in scientific research requires no further elaboration, ethical norms assume greater significance during experimentation with poxviruses. In this chapter, we will update the readers on the sensitive nature of conducting research with poxviruses, and how these viruses can be a source of potential biological weapons. Finally, specified ethical guidelines are explored to ensure safe research practices in virology.

Treatment and Vaccination for Smallpox and Monkeypox.

The smallpox infection with the variola virus was one of the most fatal disorders until a global eradication was initiated in the twentieth century. The last cases were reported in Somalia 1977 and as a laboratory infection in the UK 1978; in 1980, the World Health Organization (WHO) declared smallpox for extinct. The smallpox virus with its very high transmissibility and mortality is still a major biothreat, because the vaccination against smallpox was stopped globally in the 1980s. For this reason, new antivirals (cidofovir, brincidofovir, and tecovirimat) and new vaccines (ACAM2000, LC16m8 and Modified Vaccine Ankara MVA) were developed. For passive immunization, vaccinia immune globulin intravenous (VIGIV) is available. Due to the relationships between orthopox viruses such as vaccinia, variola, mpox (monkeypox), cowpox, and horsepox, the vaccines (LC16m8 and MVA) and antivirals (brincidofovir and tecovirimat) could also be used in the mpox outbreak with positive preliminary data. As mutations can result in drug resistance against cidofovir or tecovirimat, there is need for further research. Further antivirals (NIOCH-14 and ST-357) and vaccines (VACΔ6 and TNX-801) are being developed in Russia and the USA. In conclusion, further research for treatment and prevention of orthopox infections is needed and is already in progress. After a brief introduction, this chapter presents the smallpox and mpox disease and thereafter full overviews on antiviral treatment and vaccination including the passive immunization with vaccinia immunoglobulins.

Poxviridae Pneumonia.

Poxviridae family includes several viruses that infecting humans usually causes skin lesions only, but in some cases their clinical course is complicated by viral pneumonia (with or without bacterial superinfections). Historically variola virus has been the poxviridae most frequently associated with the development of pneumonia with many large outbreaks worldwide before its eradication in 1980. It is still considered a biological threat for its potential in biological warfare and bioterrorism. Smallpox pneumonia can be severe with the onset of acute respiratory distress syndrome (ARDS) and death. Vaccinia virus, used for vaccination against smallpox exceptionally, in immunocompromised patients, can induce generalized (with also lung involvement) severe disease after vaccination. MPXV virus occasionally can cause pneumonia particularly in immunocompromised patients. The pathophysiology of poxviridae pneumonia is still an area of active research; however, in animal models these viruses can cause both direct damage to the lower airways epithelium and a hyperinflammatory syndrome, like a cytokine storm. Multiple mechanisms of immune evasion have also been described. The treatment of poxviridae pneumonia is mainly based on careful supportive care. Despite the absence of randomized clinical trials in patients with poxviridae pneumonia there are antiviral drugs, such as tecovirimat, cidofovir and brincidofovir, FDA-approved for use in smallpox and also available under an expanded access protocol for treatment of MPXV. There are 2 (replication-deficient modified vaccinia Ankara and replication-competent vaccinia virus) smallpox vaccines FDA-approved with the first one also approved for prevention of MPXV in adults that are at high risk of infection.

Cross-reactive antibody response to Monkeypox virus surface proteins in a small proportion of individuals with and without Chinese smallpox vaccination history.

BACKGROUND: After the eradication of smallpox in China in 1979, vaccination with the vaccinia virus (VACV) Tiantan strain for the general population was stopped in 1980. As the monkeypox virus (MPXV) is rapidly spreading in the world, we would like to investigate whether the individuals with historic VACV Tiantan strain vaccination, even after more than 40 years, could still provide ELISA reactivity and neutralizing protection; and whether the unvaccinated individuals have no antibody reactivity against MPXV at all. RESULTS: We established serologic ELISA to measure the serum anti-MPXV titer by using immunodominant MPXV surface proteins, A35R, B6R, A29L, and M1R. A small proportion of individuals (born before 1980) with historic VACV Tiantan strain vaccination exhibited serum ELISA cross-reactivity against these MPXV surface proteins. Consistently, these donors also showed ELISA seropositivity and serum neutralization against VACV Tiantan strain. However, surprisingly, some unvaccinated young adults (born after 1980) also showed potent serum ELISA activity against MPXV proteins, possibly due to their past infection by some self-limiting Orthopoxvirus (OPXV). CONCLUSIONS: We report the serum ELISA cross-reactivity against MPXV surface protein in a small proportion of individuals both with and without VACV Tiantan strain vaccination history. Combined with our serum neutralization assay against VACV and the recent literature about mice vaccinated with VACV Tiantan strain, our study confirmed the anti-MPXV cross-reactivity and cross-neutralization of smallpox vaccine using VACV Tiantan strain. Therefore, it is necessary to restart the smallpox vaccination program in high risk populations.