Therapeutic and prophylactic drugs to treat orthopoxvirus infections

Monkeypox: Origin, Transmission, Clinical Manifestations, Prevention, and Therapeutic Options

Monkeypox is a rapidly spreading transmissible disease induced by the monkeypox virus (MPXV), a major public health problem worldwide. The origin of monkeypox might be tracked to the continent of Africa, where it first afflicted primate species prior to spreading to the world. Severe health issues for the public have been raised as a result of the disease's current breakouts in nonendemic areas and its subsequent dissemination to several nations throughout the globe. Monkeypox spreads by having contact with infected creatures or people, as well as respiratory droplets and contaminated things. Symptoms of monkeypox in young children and adults are different. While the symptoms are similar to smallpox, monkeypox has a reduced mortality rate. Proper diagnosis, suitable care, and focused preventative efforts all depend on becoming cognizant of those distinctions. Numerous promising therapeutic approaches have been recently investigated. Antiviral drugs such as tecovirimat, cidofovir, and brincidofovir, which were initially developed to treat smallpox, were found to have been effective in treating MPXV cases. Moreover, vaccinations continue to be an important preventative step. The purpose of this article is to offer the most recent and thorough information available on monkeypox, including its possible causes, modes of transfer, and potential treatments. By identifying the distinct forms of monkeypox and exploring potential treatment options, this work contributes to the ongoing battle against MPXVs and the management of this novel viral disease. To stop the propagation of monkeypox, greater research and communication are needed to provide stronger treatments and effective vaccinations.

Phytocompounds from Phyllanthus acidus (L.) Skeels in the management of Monkeypox Virus infections

Monkeypox is a communicable disease similar to smallpox, primarily occurring in African countries. However, recently it has spread to countries outside Africa and may arise as the next threat after COVID-pandemic. The causative organism, i.e. Monkeypox Virus (MPV) spreads from one individual to another primarily through inhalation of respiratory droplets or through contact with skin lesions of infected individuals. No known drugs are available specifically for MPV. Due to its similarity with smallpox, treatment of monkeypox is being attempted through the administration of the smallpox vaccine. Therefore, we evaluated the efficacy of the plant Phyllanthus acidus against MPV since it is traditionally used in the treatment of chickenpox and smallpox. Through functional annotation, PASS prediction and Network pharmacology analysis, the effectiveness of these chosen P. acidus-derived phytocompounds against MPV was confirmed. Target prediction of the phytocompounds identified in GC-MS analysis of the plant extract showed them to be associated with 76 human proteins. The compounds also show good binding affinity with selected viral proteins: DNA polymerase (DNApol), Putative Virulence Factor (vPVF) and Cytokine Binding Protein. Prediction of Activity Spectra for Substances (PASS) and functional annotation of the target proteins further support their antiviral nature through interaction with these proteins. The compounds were found to modulate pathways related to symptoms of viral infection and this may help in maintaining homeostasis. Our study demonstrates antiviral activity as well as the therapeutic potential of the plant against MPV infection.Communicated by Ramaswamy H. Sarma.

Machine learning and classical MD simulation to identify inhibitors against the P37 envelope protein of monkeypox virus

Monkeypox virus (MPXV) outbreak is a serious public health concern that requires international attention. P37 of MPXV plays a pivotal role in DNA replication and acts as one of the promising targets for antiviral drug design. In this study, we intent to screen potential analogs of existing FDA approved drugs of MPXV against P37 using state-of-the-art machine learning and computational biophysical techniques. AlphaFold2 guided all-atoms molecular dynamics simulations optimized P37 structure is used for molecular docking and binding free energy calculations. Similar to members of Phospholipase-D family , the predicted P37 structure also adopts a β-α-β-α-β sandwich fold, harbouring strongly conserved HxKxxxxD motif. The binding pocket comprises of Tyr48, Lys86, His115, Lys117, Ser130, Asn132, Trp280, Asn240, His325, Lys327 and Tyr346 forming strong hydrogen bonds and dense hydrophobic contacts with the screened analogs and is surrounded by positively charged patches. Loops connecting the two domains and C-terminal region exhibit high degree of flexibility. In some structural ensembles, the partial disorderness in the C-terminal region is presumed to be due to its low confidence score, acquired during structure prediction. Transition from loop to β-strands (244-254 aa) in P37-Cidofovir and its analog complexes advocates the need for further investigations. MD simulations support the accuracy of the molecular docking results, indicating the potential of analogs as potent binders of P37. Taken together, our results provide preferable understanding of molecular recognition and dynamics of ligand-bound states of P37, offering opportunities for development of new antivirals against MPXV. However, the need of in vitro and in vivo assays for confirmation of these results still persists.Communicated by Ramaswamy H. Sarma.

Synergistic effect of two human-like monoclonal antibodies confers protection against orthopoxvirus infection

The eradication of smallpox was officially declared by the WHO in 1980, leading to discontinuation of the vaccination campaign against the virus. Consequently, immunity against smallpox and related orthopoxviruses like Monkeypox virus gradually declines, highlighting the need for efficient countermeasures not only for the prevention, but also for the treatment of already exposed individuals. We have recently developed human-like monoclonal antibodies (mAbs) from vaccinia virus-immunized non-human primates. Two mAbs, MV33 and EV42, targeting the two infectious forms of the virus, were selected for in vivo evaluation, based on their in vitro neutralization potency. A single dose of either MV33 or EV42 administered three days post-infection (dpi) to BALB/c female mice provides full protection against lethal ectromelia virus challenge. Importantly, a combination of both mAbs confers full protection even when provided five dpi. Whole-body bioimaging and viral load analysis reveal that combination of the two mAbs allows for faster and more efficient clearance of the virus from target organs compared to either MV33 or EV42 separately. The combined mAbs treatment further confers post-exposure protection against the currently circulating Monkeypox virus in Cast/EiJ female mice, highlighting their therapeutic potential against other orthopoxviruses.

Pockenvirusinfektionen in der Dermatologie: Poxvirus infections in dermatology - the neglected, the notable, and the notorious

Die Familie Poxviridae umfasst derzeit 22 Gattungen, die Wirbeltiere infizieren können. Humanpathogene Pockenviren gehören den Gattungen Ortho‐, Para‐, Mollusci‐ und Yatapoxvirus an. Bis zur Eradikation der Variola vera im Jahr 1979 waren die Pocken, im Volksmund auch Blattern genannt, eine schwerwiegende Gesundheitsbedrohung für die Bevölkerung. Noch heute sind Dermatologen mit zahlreichen Pockenvirusinfektionen konfrontiert, wie den Bauernhofpocken, die als Zoonosen nach Tierkontakten in ländlichen Gebieten oder nach Massenversammlungen auftreten können. In den Tropen können Erkrankungen durch Tanapox‐ oder Vaccinia‐Viren zu den Differenzialdiagnosen gehören. Dellwarzen sind weltweit verbreitet und werden in bestimmten Fällen als sexuell übertragbare Pockenvirusinfektion angesehen. In jüngster Zeit hatten sich Mpox (Affenpocken) zu einer gesundheitlichen Notlage von internationaler Tragweite entwickelt, die eine rasche Identifizierung und angemessene Behandlung durch Dermatologen und Infektiologen erfordert. Fortschritte und neue Erkenntnisse über Epidemiologie, Diagnose, klinische Manifestationen und Komplikationen sowie Behandlung und Prävention von Pockenvirusinfektionen erfordern ein hohes Maß an Fachwissen und interdisziplinärer Zusammenarbeit in den Bereichen Virologie, Infektiologie und Dermatologie. Dieser CME‐Artikel bietet einen aktualisierten systematischen Überblick, um praktizierende Dermatologen bei der Identifizierung, Differenzialdiagnose und Behandlung klinisch relevanter Pockenvirusinfektionen zu unterstützen.

Poxvirus infections in dermatology - the neglected, the notable, and the notorious

The family Poxviridae currently comprises 22 genera that infect vertebrates. Of these, members of the Ortho-, Para-, Mollusci- and Yatapoxvirus genera have been associated with human diseases of high clinical relevance in dermatology. Historically, smallpox had been a notorious health threat until it was declared eradicated by the World Health Organization in 1979. Today, dermatologists are confronted with a variety of poxviral infections, such as farmyard pox, which occurs as a zoonotic infection after contact with animals. In the tropics, tanapox or vaccinia may be in the differential diagnosis as neglected tropical dermatoses. Molluscum contagiosum virus infection accounts for significant disease burden worldwide and is classified as a sexually transmitted infection in certain scenarios. Recently, mpox (monkeypox) has emerged as a public health emergency of international concern, requiring rapid recognition and appropriate management by dermatologists and infectious disease specialists. Advances and new insights into the epidemiology, diagnosis, clinical manifestations and complications, treatment, and prevention of poxviral infections require a high level of expertise and interdisciplinary skills from healthcare professionals linking virology, infectious diseases, and dermatology. This CME article provides a systematic overview and update to assist the practicing dermatologist in the identification, differential diagnosis, and management of poxviral infections.

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.

A 4-month-old male baby with an orf lesion on his nose: a rare case report

Background

Ecthyma contagiosum, sometimes referred to as human orf, is a zoonotic disease caused by the orf virus that is mostly acquired by coming into contact with diseased animals such as sheep or goats. The orf virus, a DNA virus belonging to the Poxviridae family, infects epidermal keratinocytes via breaking down the skin barrier, which can be caused by burns or wounds. The accompanying characteristic skin lesions can take on a range of morphologies depending on the infection's stage; lesions that are crusted, papillomatous, maculopapular, targetoid, and nodular can occur before clearing up. In addition to the lips and corners of the mouth, infected animals may also have lesions on the neck, vulva, and teeth. Skin sores caused by Ecthyma contagiousum discharge the orf virus into the environment.

Case presentation

A 4-month-old male infant with no medical history brought himself to the dermatology clinic with a minor fever and a skin lesion on his nose. An orf virus infection was discovered in the newborn through blood culture and PCR testing. For a subsequent infection, the patient received fusidic acid cream, an antibiotic, and an antipyretic. Following a follow-up of 3 months, the lesion vanished entirely.

Conclusion

Rarely, as in our instance, are orf nodules seen somewhere else than the hands. In order to appropriately treat a patient without fear, clinicians should keep this in mind, especially if they come up with a history similar to that of our patient.

Monkeypox: Virology, laboratory diagnosis and therapeutic approach

Monkeypox infection outbreaks have been observed sporadically in Africa, usually as a result of interaction with wildlife reservoirs. The genomes of the new strain range in size from 184.7 to 198.0 kb and are identified with 143-214 open reading frames. Viral cores are rapidly carried on microtubules away from the cell's perimeter and deeper into the cytoplasm once the virus and cell membranes fuse. Depending on the kind of exposure, patients with monkeypox may experience a febrile prodrome 5-13 days after exposure, which frequently includes lymphadenopathy, malaise, headaches, and muscle aches. A different diagnostic approach is available for monkeypox, including histopathological analysis, electron microscopy, immunoassays, polymerase chain reaction, genome sequencing, microarrays, loop-mediated isothermal amplification technology and CRISPR (i.e., "clustered regularly interspaced short palindromic repeats"). There are currently no particular, clinically effective treatments available for the monkeypox virus. An initial treatment is cidofovir. As a monophosphate nucleotide analog, cidofovir is transformed into an inhibitor of viral DNA polymerase by cellular kinases, which is analogous to cidofovir's function in inhibiting viral DNA synthesis. The European Medicine Agency and the Food and Drug Administration have both granted permission for IMVAMUNE, a replication-deficient, attenuated third-generation modified vaccinia Ankara vaccine, to be used for the prevention of smallpox and monkeypox in adults.

Insights on monkeypox disease and its recent outbreak with evidence of nonsynonymous missense mutation

The 2022 monkeypox outbreak has created a new global health threat and pandemic. Monkeypox virus is a descendant of the genus Orthopoxvirus, producing a febrile skin rash disease in humans. Monkeypox is zoonotic transmitted and transmitted from human to human in several ways. Even though this disease is self-limited, it creates important community health worries due to its inconvenience and widespread complications. Herein, we discussed the up-to-date current situation of monkeypox regarding its epidemiology, clinical manifestations, current in-use therapeutics, necessary protective measures, and response to potential occurrences considering the recent pandemic. Also, in this review, a comparative genomic analysis of the recent circulating strains that have been recovered from various countries including, Egypt, USA, Spain, Japan and South Africa has been investigated.

Human MPox (Monkeypox) Virus Membranous Keratoconjunctivitis With Transient Corneal Hypoesthesia and Late Symblepharon Formation: A Novel Case and Clinical Implications

PURPOSE

The aim of this study was to describe a case of corneal involvement as an early manifestation of ocular disease in the 2022 human mpox (monkeypox) virus outbreak.

METHODS

This is a single case report with longitudinal care.

RESULTS

A 47-year-old immunocompetent man presented with viral conjunctivitis before development of skin lesions or systemic symptoms. Subsequently, he developed membranous keratoconjunctivitis and a corneal epithelial defect. Orthopoxvirus-positive polymerase chain reaction test from his ocular surface was positive. The epithelial defect did not heal with conservative treatment but was successfully treated with amniotic membrane transplantation over 8 days. Reduced corneal sensation was noted after epithelial healing, and polymerase chain reaction from the ocular surface remained positive at 17 days from symptom onset, with slowly recovering conjunctivitis at 21 days. Continued membrane formation required repeated removal but significantly improved with topical corticosteroid treatment after epithelial healing by 29 days of symptom onset. Corneal sensation normalized by 87 days from symptom onset at which time symblepharon were noted but PCR testing from the ocular surface was negative.

CONCLUSIONS

Early corneal involvement of human monkeypox virus is possible. Transient corneal hypoesthesia may be due to acute inflammation. Chronic inflammatory changes can result in symblepharon. These findings have potential implications in patient care and corneal donation.

Insights into monkeypox pathophysiology, global prevalence, clinical manifestation and treatments

On 23rd July 2022, the World Health Organization (WHO) recognized the ongoing monkeypox outbreak as a public medical crisis. Monkeypox virus (MPV), the etiological agent of monkeypox, is a zoonotic, linear, double-stranded DNA virus. In 1970, the Democratic Republic of the Congo reported the first case of MPV infection. Human-to-human transmission can happen through sexual contact, inhaled droplets, or skin-to-skin contact. Once inoculated, the viruses multiply rapidly and spread into the bloodstream to cause viremia, which then affect multiple organs, including the skin, gastrointestinal tract, genitals, lungs, and liver. By September 9, 2022, more than 57,000 cases had been reported in 103 locations, especially in Europe and the United States. Infected patients are characterized by physical symptoms such as red rash, fatigue, backache, muscle aches, headache, and fever. A variety of medical strategies are available for orthopoxviruses, including monkeypox. Monkeypox prevention following the smallpox vaccine has shown up to 85% efficacy, and several antiviral drugs, such as Cidofovir and Brincidofovir, may slow the viral spread. In this article, we review the origin, pathophysiology, global epidemiology, clinical manifestation, and possible treatments of MPV to prevent the propagation of the virus and provide cues to generate specific drugs.

Current Insights into Diagnosis, Prevention Strategies, Treatment, Therapeutic Targets, and Challenges of Monkeypox (Mpox) Infections in Human Populations

In the wake of the emergence and worldwide respread of a viral infection called Monkeypox (Mpox), there is a serious threat to the health and safety of the global population. This viral infection was endemic to the western and central parts of Africa, but has recently spread out of this endemic area to various countries, including the United Kingdom (UK), Portugal, Spain, the United States of America (USA), Canada, Sweden, Belgium, Italy, Australia, Germany, France, the Netherlands, Israel, and Mexico. This is a timely review focusing on recent findings and developments in the epidemiology, clinical features, therapeutic targets, diagnosis, prevention mechanisms, research challenges and possible treatment for Mpox. To date (29 November 2022), there have been around 81,225 reported cases of Mpox. In most cases, this illness is mild; however, there is a fatality rate ranging from 1 to 10%, which might be increased due to associated complications and/or secondary infections. There is a real challenge in the diagnosis of Mpox, since its symptoms are very similar to those of other infections, including smallpox and chickenpox. Generally, to prevent/limit the risk and transmission of Mpox, the detection and isolation of infected individuals, as well as hand hygiene and cleanliness, are essential and effective approaches to control/combat this viral infection. Nevertheless, updated information about Mpox from different angles is lacking. Thus, this review provides updated and comprehensive information about the Mpox illness, which should highlight the global burden, pathogenicity, symptoms, diagnosis, prevention measures and possible treatment of this emerging disease.

Monkeypox outbreak 2022: What we know so far and its potential drug targets and management strategies

Monkeypox is a rare zoonotic disease caused by infection with the monkeypox virus. The disease can result in flu-like symptoms, fever, and a persistent rash. The disease is currently spreading throughout the world and prevention and treatment efforts are being intensified. Although there is no treatment that has been specifically approved for monkeypox virus infection, infected patients may benefit from using certain antiviral medications that are typically prescribed for the treatment of smallpox. The drugs are tecovirimat, brincidofovir, and cidofovir, all of which are currently in short supply due to the spread of the monkeypox virus. Resistance is also a concern, as widespread replication of the monkeypox virus can lead to mutations that produce monkeypox viruses that are resistant to the currently available treatments. This article discusses monkeypox disease, potential drug targets, and management strategies to overcome monkeypox disease. With the discovery of new drugs, it is hoped that the problem of insufficient drugs will be resolved, and it is not anticipated that drug resistance will become a major issue in the near future.

Results of the first German external quality assessment scheme for the detection of monkeypox virus DNA

BACKGROUND

In May 2022, the monkeypox virus (MPXV) spread into non-endemic countries and the global community was quick to test the lessons learned from the SARS-CoV-2 pandemic. Due to its symptomatic resemblance to other diseases, like the non-pox virus varicella zoster (chickenpox), polymerase chain reaction methods play an important role in correctly diagnosing the rash-causing pathogen. INSTAND quickly established a new external quality assessment (EQA) scheme for MPXV and orthopoxvirus (OPXV) DNA detection to assess the current performance quality of the laboratory tests.

METHODS

We analyzed quantitative and qualitative data of the first German EQA for MPXV and OPXV DNA detection. The survey included one negative and three MPXV-positive samples with different MPX viral loads. The threshold cycle (Ct) or other measures defining the quantification cycle (Cq) were analyzed in an assay-specific manner. A Passing Bablok fit was used to investigate the performance at laboratory level.

RESULTS

141 qualitative datasets were reported by 131 laboratories for MPXV detection and 68 qualitative datasets by 65 laboratories for OPXV detection. More than 96% of the results were correctly identified as negative and more than 97% correctly identified as positive. An analysis of the reported Ct/Cq values showed a large spread of these values of up to 12 Ct/Cq. Nevertheless, there is a good correlation of results for the different MPXV concentrations at laboratory level. Only a few quantitative results in copies/mL were reported (MPXV: N = 5; OPXV: N = 2), but the results correlated well with the concentration differences between the EQA samples, which were to a power of ten each.

CONCLUSION

The EQA results show that laboratories performed well in detecting both MPXV and OPXV. However, Ct/Cq values should be interpreted with caution when conclusions are drawn about the viral load as long as metrological traceability is not granted.

Monkeypox Disease: History, Epidemiology, Threat Assessment, and Management Strategies

Infection with the monkeypox virus is more prevalent among genus Funisciurus squirrels, less prevalent among genus Heliosurus squirrels, and rare among forest monkeys. These squirrels inhabit secondary woods close to human settlements in rural Zaire, particularly where oil palm is cultivated. In Prime Rain Forest, they are in short supply. The monkeypox virus often affects children between the ages of 5 and 9, particularly in rural settings where children hunt and consume squirrels and other small animals. Animal husbandry will minimize the danger and occurrence of human monkeypox, even in areas where the virus has spread to squirrels, as the human population grows and relies primarily on animals for animal protein. Population expansion and economic development in West and Central Africa may lessen the danger of monkeypox infection in people, but visitors who interact with animals should be vaccinated against smallpox. The spread of monkeypox can be stopped by measures such as post-exposure vaccination, contact tracing, case identification, and isolation of infectious patients. The recent monkeypox incidence is of further concern in light of the current COVID-19 pandemic.

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.

Clinical manifestations of human monkeypox infection and implications for outbreak strategy

Monkeypox is an orthopoxvirus-based zoonotic illness that causes symptoms similar to smallpox in humans. Health care workers around the world are making it a priority to educate themselves on the many clinical manifestations and treatment options for this virus as public health agencies strive to stop the current outbreak. The infected do not have access to any treatment at this time. However, information obtained from the smallpox pandemic has led researchers to examine vaccinia immune globulin (IVG), tecovirimat, and cidofovir as viable treatments for monkeypox. Moreover, medication like tecovirimat may be given in extreme circumstances, and supportive therapy can help with symptom relief. The European Medicines Agency (EMA) certified tecovirimat as safe and effective against monkeypox in 2022, per the World Health Organization (WHO). As there are now no established guidelines for alleviating these symptoms, the efficacy of these treatments is highly questionable. Some high-profile cases in recent years have cast doubt on the long-held belief that this illness is rare and always resolves itself without treatment. We aimed to conduct this review to get a deeper comprehension of the evolving epidemiology of monkeypox by analysing such factors as the number of confirmed, probable, and potential cases, the median age at presentation, the mortality rate, and the geographic distribution of the disease. This study offers an updated review of monkeypox and the clinical treatments that are currently available as a result of the worldwide epidemics.

Neurologic Complications of Smallpox and Monkeypox: A Review

Importance

Orthopox viruses include smallpox virus, a once feared but now eradicated virus, as well as monkeypox virus. Monkeypox is an emerging virus initially isolated in 1958, previously unrecognized outside sub-Saharan Africa until a worldwide outbreak in May 2022. It is important to review known neurologic consequences of both these viruses, as complications of smallpox may be relevant to monkeypox, though complications of monkeypox may be rarer and perhaps less severe.

Observations

This was a literature review of the known neurologic complications of smallpox, which include encephalitis, transverse myelitis, and acute disseminated encephalomyelitis among others; historical complications of smallpox vaccination, including postvaccinal encephalomyelitis; and the known neurologic complications of monkeypox, which include headaches and mood disturbances, as well as rare presentations of encephalitis, transverse myelitis, and seizures. Of concern is the possibility of viral persistence and systemic complications in immunocompromised individuals. Also provided were considerations for diagnosis, current treatment, and prevention of monkeypox.

Conclusions and Relevance

Monkeypox should be considered in high-risk populations who present with neurologic syndromes. Diagnosis may require serology and polymerase chain reaction testing of blood and spinal fluid. Antiviral therapy should be initiated early in the course of the illness.

The 2022 outbreak and the pathobiology of the monkeypox virus

Following two reports of monkeypox virus infection in individuals who returned from Nigeria to the USA, one who returned to Texas (July 2021) and the other to the Washington, DC area (November 2021), the number of monkeypox infection have dramatically increased. This sounded an alarm of potential for spreading of the virus throughout the USA. During 2022, there was a report of monkeypox virus infection (May 6, 2022) in a British national following a visit to Nigeria who developed readily recognizable signs and symptoms of monkeypox virus infection. Soon following this report, case numbers climbed. By June 10, 2022, more than 1,500 cases were reported in 43 countries, including Europe and North America. While the prevalence of the monkeypox virus is well known in central and western Africa, its presence in the developed world has raised disturbing signs for worldwide spread. While infection was reported during the past half-century, starting in the Democratic Republic of Congo in 1970, in the United States, only sporadic monkeypox cases have been reported. All cases have been linked to international travel or through African animal imports. The monkeypox virus is transmitted through contact with infected skin, body fluids, or respiratory droplets. The virus spreads from oral and nasopharyngeal fluid exchanges or by intradermal injection; then rapidly replicates at the inoculation site with spreads to adjacent lymph nodes. Monkeypox disease begins with constitutional symptoms that include fever, chills, headache, muscle aches, backache, and fatigue. Phylogenetically the virus has two clades. One clade emerged from West Africa and the other in the Congo Basin of Central Africa. During the most recent outbreak, the identity of the reservoir host or the primary carriage remains unknown. African rodents are the suspected intermediate hosts. At the same time, the Centers for Disease Control (CDC) affirmed that there are no specific treatments for the 2022 monkeypox virus infection; existing antivirals shown to be effective against smallpox may slow monkeypox spread. A smallpox vaccine JYNNEOS (Imvamune or Imvanex) may also be used to prevent infection. The World Health Organization (WHO), has warned that the world could be facing a formidable infectious disease challenge in light of the current status of worldwide affairs. These affairs include the SARS-COVID-19 pandemic and the Ukraine-Russia war. In addition, the recent rise in case of numbers worldwide could continue to pose an international threat. With this in mind, strategies to mitigate the spread of monkeypox virus are warranted.

CRISPR/Cas9 as an antiviral against Orthopoxviruses using an AAV vector

A vaccine for smallpox is no longer administered to the general public, and there is no proven, safe treatment specific to poxvirus infections, leaving people susceptible to infections by smallpox and other zoonotic Orthopoxviruses such as monkeypox. Using vaccinia virus (VACV) as a model organism for other Orthopoxviruses, CRISPR-Cas9 technology was used to target three essential genes that are conserved across the genus, including A17L, E3L, and I2L. Three individual single guide RNAs (sgRNAs) were designed per gene to facilitate redundancy in rendering the genes inactive, thereby reducing the reproduction of the virus. The efficacy of the CRISPR targets was tested by transfecting human embryonic kidney (HEK293) cells with plasmids encoding both SaCas9 and an individual sgRNA. This resulted in a reduction of VACV titer by up to 93.19% per target. Following the verification of CRISPR targets, safe and targeted delivery of the VACV CRISPR antivirals was tested using adeno-associated virus (AAV) as a packaging vector for both SaCas9 and sgRNA. Similarly, AAV delivery of the CRISPR antivirals resulted in a reduction of viral titer by up to 92.97% for an individual target. Overall, we have identified highly specific CRISPR targets that significantly reduce VACV titer as well as an appropriate vector for delivering these CRISPR antiviral components to host cells in vitro.

SUCCESSFUL TREATMENT OF CLINICAL ORTHOPOXVIRUS INFECTION IN A GIANT ANTEATER (MYRMECOPHAGA TRIDACTYLA)

An anorexic 5-yr-old female giant anteater (Myrmecophaga tridactyla) developed multifocal ulcerative and vesicular lesions affecting the rostrum, oral cavity, and tongue. Disseminated skin lesions were also found on the body, affecting the feet, flanks, and genital area. Polymerase chain reaction confirmed a systemic viremic orthopoxvirus infection. Cowpox virus was considered to be the only likely etiological agent. Intensive supportive treatment, including daily fluid therapy, force-feeding, and anti-inflammatory administration achieved a successful outcome after 3 wk. To the authors' knowledge, this is the first time a giant anteater with severe orthopoxvirus lesions has survived the disease. This unique case discusses current and possible future therapeutic and prophylactic options for the treatment of orthopoxvirus infections in giant anteaters and other nondomestic animal species.

The Possibility of Using the ICR Mouse as an Animal Model to Assess Antimonkeypox Drug Efficacy

As a result of the conducted experimental studies on intranasal challenge of ICR mice, rabbits and miniature pigs (even in the maximum variant) with the doses of 4.0-5.5 lg PFU of monkeypox virus (MPXV), some clinical signs such as purulent conjunctivitis, blepharitis and ruffled fur were found only in mice. The 50% infective dose (C ID50 ) of MPXV for these animals estimated by the presence of external clinical signs was 4.8 lg PFU, and L ID50 estimated by the virus presence in the lungs of mice 7 days post-infection taking into account its 10% application in the animal respiratory tract was 1.4 lg PFU. When studying the dynamics of MPXV propagation in mice challenged intranasally with 25 L ID50 of MPXV, the maximum pathogen accumulation was revealed in nasal cavity, lungs and brain: 5.7 ± 0.1, 5.5 ± 0.1 and 5.3 ± 0.3 lg PFU/ml, respectively. The pathomorphological examination of these animals revealed the presence and replication of the pathogen in the traditional primary target cells for MPXV (mononuclear phagocyte system cells and respiratory tract epitheliocytes) as well as in some other types of cells (endothelial cells, reticular cells, connective tissue cells). Our use of these animals to assess the antiviral efficacy of some drugs demonstrated the agreement of the results (a significant positive effect of NIOCH-14 and ST-246) with those described in scientific literature, which opens up the prospects of using ICR mice as animal models for monkeypox to develop preventive antismallpox drugs.

Co-administration of the broad-spectrum antiviral, brincidofovir (CMX001), with smallpox vaccine does not compromise vaccine protection in mice challenged with ectromelia virus

Natural orthopoxvirus outbreaks such as vaccinia, cowpox, cattlepox and buffalopox continue to cause morbidity in the human population. Monkeypox virus remains a significant agent of morbidity and mortality in Africa. Furthermore, monkeypox virus’s broad host-range and expanding environs make it of particular concern as an emerging human pathogen. Monkeypox virus and variola virus (the etiological agent of smallpox) are both potential agents of bioterrorism. The first line response to orthopoxvirus disease is through vaccination with first-generation and second-generation vaccines, such as Dryvax and ACAM2000. Although these vaccines provide excellent protection, their widespread use is impeded by the high level of adverse events associated with vaccination using live, attenuated virus. It is possible that vaccines could be used in combination with antiviral drugs to reduce the incidence and severity of vaccine-associated adverse events, or as a preventive in individuals with uncertain exposure status or contraindication to vaccination. We have used the intranasal mousepox (ectromelia) model to evaluate the efficacy of vaccination with Dryvax or ACAM2000 in conjunction with treatment using the broad spectrum antiviral, brincidofovir (BCV, CMX001). We found that co-treatment with BCV reduced the severity of vaccination-associated lesion development. Although the immune response to vaccination was quantifiably attenuated, vaccination combined with BCV treatment did not alter the development of full protective immunity, even when administered two days following ectromelia challenge. Studies with a non-replicating vaccine, ACAM3000 (MVA), confirmed that BCV’s mechanism of attenuating the immune response following vaccination with live virus was, as expected, by limiting viral replication and not through inhibition of the immune system. These studies suggest that, in the setting of post-exposure prophylaxis, co-administration of BCV with vaccination should be considered a first response to a smallpox emergency in subjects of uncertain exposure status or as a means of reduction of the incidence and severity of vaccine-associated adverse events.

Human monkeypox

Human monkeypox is a zoonotic Orthopoxvirus with a presentation similar to smallpox. Clinical differentiation of the disease from smallpox and varicella is difficult. Laboratory diagnostics are principal components to identification and surveillance of disease, and new tests are needed for a more precise and rapid diagnosis. The majority of human infections occur in Central Africa, where surveillance in rural areas with poor infrastructure is difficult but can be accomplished with evidence-guided tools and educational materials to inform public health workers of important principles. Contemporary epidemiological studies are needed now that populations do not receive routine smallpox vaccination. New therapeutics and vaccines offer hope for the treatment and prevention of monkeypox; however, more research must be done before they are ready to be deployed in an endemic setting. There is a need for more research in the epidemiology, ecology, and biology of the virus in endemic areas to better understand and prevent human infections.

A review of experimental and natural infections of animals with monkeypox virus between 1958 and 2012

Monkeypox virus (MPXV) was discovered in 1958 during an outbreak in an animal facility in Copenhagen, Denmark. Since its discovery, MPXV has revealed a propensity to infect and induce disease in a large number of animals within the mammalia class from pan-geographical locations. This finding has impeded the elucidation of the natural host, although the strongest candidates are African squirrels and/or other rodents. Experimentally, MPXV can infect animals via a variety of multiple different inoculation routes; however, the natural route of transmission is unknown and is likely to be somewhat species specific. In this review we have attempted to compile and discuss all published articles that describe experimental or natural infections with MPXV, dating from the initial discovery of the virus through to the year 2012. We further discuss the comparative disease courses and pathologies of the host species.

A single cidofovir treatment rescues animals at progressive stages of lethal orthopoxvirus disease

BACKGROUND

In an event of a smallpox outbreak in humans, the window for efficacious treatment by vaccination with vaccinia viruses (VACV) is believed to be limited to the first few days post-exposure (p.e.). We recently demonstrated in a mouse model for human smallpox, that active immunization 2-3 days p.e. with either VACV-Lister or modified VACV Ankara (MVA) vaccines, can rescue animals from lethal challenge of ectromelia virus (ECTV), the causative agent of mousepox. The present study was carried out in order to determine whether a single dose of the anti-viral cidofovir (CDV), administered at different times and doses p.e. either alone or in conjunction with active vaccination, can rescue ECTV infected mice.

METHODS

Animals were infected intranasally with ECTV, treated on different days with various single CDV doses and monitored for morbidity, mortality and humoral response. In addition, in order to determine the influence of CDV on the immune response following vaccination, both the "clinical take", IFN-gamma and IgG Ab levels in the serum were evaluated as well as the ability of the mice to withstand a lethal challenge of ECTV. Finally the efficacy of a combined treatment regime of CDV and vaccination p.e. was determined.

RESULTS

A single p.e. CDV treatment is sufficient for protection depending on the initiation time and dose (2.5 - 100 mg/kg) of treatment. Solid protection was achieved by a low dose (5 mg/kg) CDV treatment even if given at day 6 p.e., approximately 4 days before death of the control infected untreated mice (mean time to death (MTTD) 10.2). At the same time point complete protection was achieved by single treatment with higher doses of CDV (25 or 100 mg/kg). Irrespective of treatment dose, all surviving animals developed a protective immune response even when the CDV treatment was initiated one day p.e.. After seven days post treatment with the highest dose (100 mg/kg), virus was still detected in some organs (e.g. lung and liver) yet all animals survived, suggesting that efficacious single CDV treatment requires a potent immune system. The combination of CDV and vaccination provided no additional protection over CDV alone. Yet, combining CDV and vaccination maintained vaccination efficacy.

CONCLUSIONS

Altogether, our data substantiate the feasibility of single post-exposure antiviral treatment to face orthopoxvirus infection.

In vitro characterization of a nineteenth-century therapy for smallpox

In the nineteenth century, smallpox ravaged through the United States and Canada. At this time, a botanical preparation, derived from the carnivorous plant Sarracenia purpurea, was proclaimed as being a successful therapy for smallpox infections. The work described characterizes the antipoxvirus activity associated with this botanical extract against vaccinia virus, monkeypox virus and variola virus, the causative agent of smallpox. Our work demonstrates the in vitro characterization of Sarracenia purpurea as the first effective inhibitor of poxvirus replication at the level of early viral transcription. With the renewed threat of poxvirus-related infections, our results indicate Sarracenia purpurea may act as another defensive measure against Orthopoxvirus infections.

Evaluation of disease and viral biomarkers as triggers for therapeutic intervention in respiratory mousepox - an animal model of smallpox

The human population is currently faced with the potential use of natural or recombinant variola and monkeypox viruses as biological weapons. Furthermore, the emergence of human monkeypox in Africa and its expanding environs poses a significant natural threat. Such occurrences would require therapeutic and prophylactic intervention with antivirals to minimize morbidity and mortality of exposed populations. Two orally-bioavailable antivirals are currently in clinical trials; namely CMX001, an ether-lipid analog of cidofovir with activity at the DNA replication stage and ST-246, a novel viral egress inhibitor. Both of these drugs have previously been evaluated in the ectromelia/mousepox system; however, the trigger for intervention was not linked to a disease biomarker or a specific marker of virus replication. In this study we used lethal, intranasal, ectromelia virus infections of C57BL/6 and hairless SKH1 mice to model human disease and evaluate exanthematous rash (rash) as an indicator to initiate antiviral treatment. We show that significant protection can be provided to C57BL/6 mice by CMX001 or ST-246 when therapy is initiated on day 6 post infection or earlier. We also show that significant protection can be provided to SKH1 mice treated with CMX001 at day 3 post infection or earlier, but this is four or more days before detection of rash (ST-246 not tested). Although in this model rash could not be used as a treatment trigger, viral DNA was detected in blood by day 4 post infection and in the oropharyngeal secretions (saliva) by day 2–3 post infection – thus providing robust and specific markers of virus replication for therapy initiation. These findings are discussed in the context of current respiratory challenge animal models in use for the evaluation of poxvirus antivirals.

Zoonotic Poxviruses Associated with Companion Animals

Simple Summary

Contemporary enthusiasm for the ownership of exotic animals and hobby livestock has created an opportunity for the movement of poxviruses—such as monkeypox, cowpox, and orf—outside their traditional geographic range bringing them into contact with atypical animal hosts and groups of people not normally considered at risk. It is important that pet owners and practitioners of human and animal medicine develop a heightened awareness for poxvirus infections and understand the risks that can be associated with companion animals and livestock. This article reviews the epidemiology and clinical features of zoonotic poxviruses that are most likely to affect companion animals.

Abstract

Understanding the zoonotic risk posed by poxviruses in companion animals is important for protecting both human and animal health. The outbreak of monkeypox in the United States, as well as current reports of cowpox in Europe, point to the fact that companion animals are increasingly serving as sources of poxvirus transmission to people. In addition, the trend among hobbyists to keep livestock (such as goats) in urban and semi-urban areas has contributed to increased parapoxvirus exposures among people not traditionally considered at high risk. Despite the historic notoriety of poxviruses and the diseases they cause, poxvirus infections are often missed. Delays in diagnosing poxvirus-associated infections in companion animals can lead to inadvertent human exposures. Delays in confirming human infections can result in inappropriate treatment or prolonged recovery. Early recognition of poxvirus-associated infections and application of appropriate preventive measures can reduce the spread of virus between companion animals and their owners. This review will discuss the epidemiology and clinical features associated with the zoonotic poxvirus infections most commonly associated with companion animals.

Zoonotic Brazilian Vaccinia virus: from field to therapy

Vaccinia virus (VACV), the prototype species of the Orthopoxvirus (OPV) genus, causes an occupational zoonotic disease in Brazil that is primarily associated with the handling of infected dairy cattle. Cattle and human outbreaks have been described in southeastern Brazil since 1999 and have now occurred in almost half of the territory. Phylogenetic studies have shown high levels of polymorphisms among isolated VACVs, which indicate the existence of at least two genetically divergent clades; this has also been proven in virulence assays in a mouse model system. In humans, VACV infection is characterized by skin lesions, primarily on the hands, accompanied by systemic symptoms such as fever, myalgia, headache and lymphadenopathy. In this review, we will discuss the virological, epidemiological, ecological and clinical aspects of VACV infection, its diagnosis and compounds that potentially could be used for the treatment of severe cases.

Poxvirus interleukin-4 expression overcomes inherent resistance and vaccine-induced immunity: pathogenesis, prophylaxis, and antiviral therapy

In 2001, Jackson et al. reported that murine IL-4 expression by a recombinant ectromelia virus caused enhanced morbidity and lethality in resistant C57BL/6 mice as well as overcame protective immune memory responses. To achieve a more thorough understanding of this phenomenon and to assess a variety of countermeasures, we constructed a series of ECTV recombinants encoding murine IL-4 under the control of promoters of different strengths and temporal regulation. We showed that the ECTV-IL-4 recombinant expressing the highest level of IL-4 was uniformly lethal for C57BL/6 mice even when previously immunized. The lethality of the ECTV-IL-4 recombinants resulted from virus-expressed IL-4 signaling through the IL-4 receptor but was not due to IL-4 toxicity. A number of treatment approaches were evaluated against the most virulent IL-4 encoding virus. The most efficacious therapy was a combination of two antiviral drugs (CMX001(®) and ST-246(®)) that have different mechanisms of action.

Ectromelia virus infections of mice as a model to support the licensure of anti-orthopoxvirus therapeutics

The absence of herd immunity to orthopoxviruses and the concern that variola or monkeypox viruses could be used for bioterroristic activities has stimulated the development of therapeutics and safer prophylactics. One major limitation in this process is the lack of accessible human orthopoxvirus infections for clinical efficacy trials; however, drug licensure can be based on orthopoxvirus animal challenge models as described in the "Animal Efficacy Rule". One such challenge model uses ectromelia virus, an orthopoxvirus, whose natural host is the mouse and is the etiological agent of mousepox. The genetic similarity of ectromelia virus to variola and monkeypox viruses, the common features of the resulting disease, and the convenience of the mouse as a laboratory animal underscores its utility in the study of orthopoxvirus pathogenesis and in the development of therapeutics and prophylactics. In this review we outline how mousepox has been used as a model for smallpox. We also discuss mousepox in the context of mouse strain, route of infection, infectious dose, disease progression, and recovery from infection.

Animal models of orthopoxvirus infection

Smallpox was one of the most devastating diseases known to humanity. Although smallpox was eradicated through a historically successful vaccination campaign, there is concern in the global community that either Variola virus (VARV), the causative agent of smallpox, or another species of Orthopoxvirus could be used as agents of bioterrorism. Therefore, development of countermeasures to Orthopoxvirus infection is a crucial focus in biodefense research, and these efforts rely on the use of various animal models. Smallpox typically presented as a generalized pustular rash with 30 to 40% mortality, and although smallpox-like syndromes can be induced in cynomolgus macaques with VARV, research with this virus is highly restricted; therefore, animal models with other orthopoxviruses have been investigated. Monkeypox virus causes a generalized vesiculopustular rash in rhesus and cynomolgus macaques and induces fatal systemic disease in several rodent species. Ectromelia virus has been extensively studied in mice as a model of orthopoxviral infection in its natural host. Intranasal inoculation of mice with some strains of vaccinia virus produces fatal bronchopneumonia, as does aerosol or intranasal inoculation of mice with cowpox virus. Rabbitpox virus causes pneumonia and fatal systemic infections in rabbits and can be naturally transmitted between rabbits by an aerosol route similar to that of VARV in humans. No single animal model recapitulates all known aspects of human Orthopoxvirus infections, and each model has its advantages and disadvantages. This article provides a brief review of the Orthopoxvirus diseases of humans and the key pathologic features of animal models of Orthopoxvirus infections.

A mouse model of lethal infection for evaluating prophylactics and therapeutics against Monkeypox virus

Monkeypox virus (MPXV) is an orthopoxvirus closely related to variola, the etiological agent of smallpox. In humans, MPXV causes a disease similar to smallpox and is considered to be an emerging infectious disease. Moreover, the use of MPXV for bioterroristic/biowarfare activities is of significant concern. Available small animal models of human monkeypox have been restricted to mammals with poorly defined biologies that also have limited reagent availability. We have established a murine MPXV model utilizing the STAT1-deficient C57BL/6 mouse. Here we report that a relatively low-dose intranasal (IN) infection induces 100% mortality in the stat1(-)(/)(-) model by day 10 postinfection with high infectious titers in the livers, spleens, and lungs of moribund animals. Vaccination with modified vaccinia virus Ankara (MVA) followed by a booster vaccination is sufficient to protect against an intranasal MPXV challenge and induces an immune response more robust than that of a single vaccination. Furthermore, antiviral treatment with CMX001 (HDP-cidofovir) and ST-246 protects when administered as a regimen initiated on the day of infection. Thus, the stat1(-)(/)(-) model provides a lethal murine platform for evaluating therapeutics and for investigating the immunological and pathological responses to MPXV infection.

The new ACAM2000 vaccine and other therapies to control orthopoxvirus outbreaks and bioterror attacks

Quarantine, case tracing and population vaccination facilitated the global eradication, in 1980, of variola virus, the causative agent of smallpox. The vaccines used during the eradication period, including Dryvax, the smallpox vaccine used in the USA, were live vaccinia and cowpoxvirus-based vaccines, which induced long-lasting and cross-protective immunity against variola and other related poxviruses. These vaccine viruses were produced by serial propagation in domesticated animals. The drawbacks to such serially propagated live viral vaccines include the level of postvaccination local and systemic reactions and contraindications to their use in immunocompromised individuals, individuals with certain skin and cardiac diseases, and pregnant women. In the latter stages of the population-based smallpox vaccination campaign, research began with ways to improve safety and modernizing the manufacture of vaccinia vaccines; however, with the eradication of variola this work stopped. Outbreaks of monkeypoxvirus in humans and the bioterrorist threat of monkeypox and variola virus renewed the need for improved vaccinia vaccines. ACAM2000 is one of the new generation of smallpox vaccines. It is produced in cell culture from a clonally purified master seed stock of vaccinia derived from the New York City Board of Health strain of vaccinia. The clonally purified master seed assures a more homogeneous vaccine without the inherent mutations associated with serial propagation and the cell culture limits adventitious and bacterial contamination in vaccine production. In preclinical and clinical trials, ACAM2000 demonstrated an immunogenicity and safety profile similar to that of Dryvax.

Transmission of atypical varicella-zoster virus infections involving palm and sole manifestations in an area with monkeypox endemicity

During a suspected monkeypox outbreak in the Republic of Congo, we documented transmission of varicella-zoster virus (VZV) infection with palm and sole manifestations among 5 family members. Genotyping results confirmed the VZV strain European E2, a genotype not previously reported in Africa. VZV with palm and sole involvement should be considered when differentiating a monkeypox diagnosis.