New Perspectives on Antimicrobial Agents: Tecovirimat for Treatment of Human Monkeypox Virus

Identification of core therapeutic targets for Monkeypox virus and repurposing potential of drugs: A WEB prediction approach

A new round of monkeypox virus has emerged in the United Kingdom since July 2022 and rapidly swept the world. Currently, despite numerous research groups are studying this virus and seeking effective treatments, the information on the open reading frame, inhibitors, and potential targets of monkeypox has not been updated in time, and the comprehension of monkeypox target ligand interactions remains a key challenge. Here, we first summarized and improved the open reading frame information of monkeypox, constructed the monkeypox inhibitor library and potential targets library by database research as well as literature search, combined with advanced protein modeling technologies (Sequence-based and AI algorithms-based homology modeling). In addition, we build monkeypox virus Docking Server, a web server to predict the binding mode between targets and substrate. The open reading frame information, monkeypox inhibitor library, and monkeypox potential targets library are used as the initial files for server docking, providing free interactive tools for predicting ligand interactions of monkeypox targets, potential drug screening, and potential targets search. In addition, the update of the three databases can also effectively promote the study of monkeypox drug inhibition mechanism and provide theoretical guidance for the development of drugs for monkeypox.

Mpox Virus and its ocular surface manifestations

The Mpox virus (MPXV) is the causative agent of human Mpox disease - a debilitating rash illness similar to smallpox. Although Clade I MPXV has remained endemic to West and Central Africa, Clade II MPXV has been responsible for many outbreaks worldwide. The most recent outbreak in 2022 resulted from the rapid spread of a new clade of MPXV, classified into Clade IIb - a distinct lineage from the previously circulating viral strains. The rapid spread and increased severity of Mpox disease by the Clade IIb strain have raised the serious public health imperative of better understanding the host and viral determinants during MPXV infection. In addition to typical skin rashes, including in the periorbital area, MPXV causes moderate to severe ophthalmic manifestations - most commonly, ocular surface complications (e.g., keratitis, conjunctivitis, blepharitis). While ocular manifestations of Clade I Mpox within the Congo basin have been well-reported, global incidence trends of ocular Mpox cases by Clade IIb are still emerging. Given the demonstrated ability of all MPXV strains to auto-inoculate ocular tissue, alongside the enhanced transmissibility of the Clade IIb virus, there is an urgent need to elucidate the mechanisms by which MPXV causes ocular anomalies. In this review, we discuss the viral and genomic structures of MPXV, the epidemiology, and pathology of systemic and ocular Mpox, as well as potential prophylactic and therapeutic interventions.

Mpox: what sexual health physicians need to know?

Monkeypox virus (MPXV) is another zoonotic virus spilled over to the man and resulted in pandemic. World Health Organization declared it as a 'Public Health Emergency of International Concern (PHEIC) on July 22, 2022. Mpox affected over 95226 individuals among them claimed the lives of 185. Despite the fact that Mpox is generally mild and self-limited, immunocompromised people with low CD4 counts may experience severe disease course. Management of Mpox patients has three pillars. First symptomatic approach includes pain management, prophylaxis for secondary infections and when needed effective treatment of superinfections. Second, vaccines developed against smallpox can be used in preexposure or postexposure prophylaxis strategies against Mpox. Third, current antiviral options include tecovirimat, cidofovir and birincidofovir all of which have been recommended relying on experience from animal studies, clinical case reports or case series. Results of well-planned randomized control trials are not available. Occupational exposure to MPXV is especially a manageable risk for health care workers. Prevention of Mpox also requires risk communication with vulnerable population and their involvement in mitigation efforts.

"Mpox in MSM: Tackling stigma, minimizing risk factors, exploring pathogenesis, and treatment approaches"

Mpox is a zoonotic disease caused by the monkeypox virus (MPV), primarily found in Central and West African countries. The typical presentation of the disease before the 2022 mpox outbreak includes a febrile prodrome 5-13 days post-exposure, accompanied by lymphadenopathy, malaise, headache, and muscle aches. Unexpectedly, during the 2022 outbreak, several cases of atypical presentations of the disease were reported, such as the absence of prodromal symptoms and the presence of genital skin lesions suggestive of sexual transmission. As per the World Health Organization (WHO), as of March 20, 2024, 94,707 cases of mpox were reported worldwide, resulting in 181 deaths (22 in African endemic regions and 159 in non-endemic countries). The United States Centers for Disease Control and Prevention (CDC) reports a total of 32,063 cases (33.85% of total cases globally), with 58 deaths (32.04% of global deaths) due to mpox. Person-to-person transmission of mpox can occur through respiratory droplets and sustained close contact. However, during the 2022 outbreak of mpox, a high incidence of anal and perianal lesions among MSMs indicated sexual transmission of MPV as a major route of transmission. Since MSMs are disproportionately at risk for HIV transmission. In this review, we discusses the risk factors, transmission patterns, pathogenesis, vaccine, and treatment options for mpox among MSM and people living with HIV (PLWH). Furthermore, we provide a brief perspective on the evolution of the MPV in immunocompromised people like PLWH.

Role of vaccination in patients with human monkeypox virus and its cardiovascular manifestations

Human monkeypox, caused by the monkeypox virus (MPXV), is an emerging infectious disease with the potential for human-to-human transmission and diverse clinical presentations. While generally considered milder than smallpox, it can lead to severe cardiovascular complications. The virus primarily spreads through contact with infected animals or through human-to-human transmission. Cardiovascular involvement in human monkeypox is rare but has been associated with myocarditis, pericarditis, arrhythmias, and even fulminant myocardial infarction. Vaccination plays a crucial role in preventing and controlling monkeypox, but the eradication of smallpox has left global populations vulnerable. This review explores the cardiovascular manifestations of human monkeypox, the role of vaccination in disease prevention, and the importance of continued research and development of effective vaccines to protect against this emerging infectious threat. The global impact of monkeypox outbreaks, particularly on vulnerable populations, further highlights the importance of understanding and addressing this disease.

Combination of Extended Antivirals With Antiretrovirals for Severe Mpox in Advanced Human Immunodeficiency Virus Infection: Case Series of 4 Patients

To gauge the safety and utility of extended tecovirimat/cidofovir for severe mpox, here we report our experience caring for 4 patients with mpox and advanced human immunodeficiency virus (HIV) at the Hospitals of the University of Pennsylvania during the 2022 global outbreak. Three patients had recurrent courses complicated by superinfections, coinfections and insufficient nutrition/housing, requiring extended tecovirimat (5-16 weeks) and cidofovir (1-12 doses) with probenecid and fluids. At follow-up, patients had undetectable HIV RNA on antiretrovirals, improved ulcers and stable renal function on antivirals. Serology guided cessation for one 7-month cidofovir course. Overall findings support a comprehensive approach of prolonged tecovirimat/cidofovir with antiretrovirals for severe mpox, while addressing social factors.

Natural compounds inhibit Monkeypox virus methyltransferase VP39 in silico studies

VP39, an essential 2'-O-RNA methyltransferase enzyme discovered in Monkeypox virus (MPXV), plays a vital role in viral RNA replication and transcription. Inhibition of the enzyme may prevent viral replication. In this context, using a combination of molecular docking and molecular dynamics (MDs) simulations, the inhibitory ability of NCI Diversity Set VII natural compounds to VP39 protein was investigated. It should be noted that the computed binding free energy of ligand via molecular docking and linear interaction energy (LIE) approaches are in good agreement with the corresponding experiments with coefficients of R = 0.72 and 0.75, respectively. NSC 319990, NSC 196515 and NSC 376254 compounds were demonstrated that can inhibit MPVX methyltransferase VP39 protein with the similar affinity compared to available inhibitor sinefungin. Moreover, nine residues involving Gln39, Gly68, Gly72, Asp95, Arg97, Val116, Asp138, Arg140 and Asn156 may be argued that they play an important role in binding process of inhibitors to VP39.Communicated by Ramaswamy H. Sarma.

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.

Mpox in Children: 3 Cases

Although the 2022 mpox outbreak mostly affected adults, its effect on children and adolescents was also substantial. In this report, we describe the clinical course and treatment of the first 3 known cases of mpox in children in New York City. These cases are instructive because they illustrate various routes of transmission, clinical presentations, and diagnostic challenges that differ from previous reports of mpox in endemic countries and previous mpox outbreaks. Of note is that each of the 3 patients received treatment with tecovirimat under an US Food and Drug Administration expanded access investigational new drug application and improved without exhibiting adverse reactions.

Early administration of tecovirimat shortens the time to mpox clearance in a model of human infection

Despite use of tecovirimat since the beginning of the 2022 outbreak, few data have been published on its antiviral effect in humans. We here predict tecovirimat efficacy using a unique set of data in nonhuman primates (NHPs) and humans. We analyzed tecovirimat antiviral activity on viral kinetics in NHP to characterize its concentration-effect relationship in vivo. Next, we used a pharmacological model developed in healthy volunteers to project its antiviral efficacy in humans. Finally, a viral dynamic model was applied to characterize mpox kinetics in skin lesions from 54 untreated patients, and we used this modeling framework to predict the impact of tecovirimat on viral clearance in skin lesions. At human-recommended doses, tecovirimat could inhibit viral replication from infected cells by more than 90% after 3 to 5 days of drug administration and achieved over 97% efficacy at drug steady state. With an estimated mpox within-host basic reproduction number, R0, equal to 5.6, tecovirimat could therefore shorten the time to viral clearance if given before viral peak. We predicted that initiating treatment at symptom onset, which on average occurred 2 days before viral peak, could reduce the time to viral clearance by about 6 days. Immediate postexposure prophylaxis could not only reduce time to clearance but also lower peak viral load by more than 1.0 log10 copies/mL and shorten the duration of positive viral culture by about 7 to 10 days. These findings support the early administration of tecovirimat against mpox infection, ideally starting from the infection day as a postexposure prophylaxis.

Inhibitors of mpox VP39 2'-O methyltransferase efficiently inhibit the monkeypox virus

The RNA 2'-O methyltransferase (MTase) VP39 of the monkeypox virus (MpxV) participates in RNA capping within poxviruses. Sub-micromolar inhibitors targeting this enzyme were already reported. However, these 7-deaza analogs of S-adenosyl methionine (SAH) had not been tested in cellular assays until now. In this study, we employed plaque assays and cytopathic effect-based assays to evaluate the effectiveness of these compounds. All tested compounds demonstrated antiviral activity against MpxV, with EC50 values ranging from 0.06 to 2.7 μM. Nevertheless, some of these compounds also exhibited cytotoxicity in HeLa cells, while others showed no toxicity. Notably, the non-toxic compounds featured a large aromatic substituent at the 7-deaza position, whereas the toxic compounds had a small substituent at the same position. These findings suggest that VP39 represents a bona fide target for the development of antiviral drugs against MpxV.

Antivirals against Monkeypox (Mpox) in Humans: An Updated Narrative Review

As of 29 August 2023, a total of 89,596 confirmed cases of Mpox (monkeypox) have been documented across 114 countries worldwide, with 157 reported fatalities. The Mpox outbreak that transpired in 2022 predominantly affected young men who have sex with men (MSM). While most cases exhibited a mild clinical course, individuals with compromised immune systems, particularly those living with HIV infection and possessing a CD4 count below 200 cells/mm3, experienced a more severe clinical trajectory marked by heightened morbidity and mortality. The approach to managing Mpox is primarily symptomatic and supportive. However, in instances characterized by severe or complicated manifestations, the utilization of antiviral medications becomes necessary. Despite tecovirimat's lack of official approval by the FDA for treating Mpox in humans, a wealth of positive clinical experiences exists, pending the outcomes of ongoing clinical trials. Brincidofovir and cidofovir have also been administered in select cases due to the unavailability of tecovirimat. Within the scope of this narrative review, our objective was to delve into the clinical attributes of Mpox and explore observational studies that shed light on the utilization of these antiviral agents.

Mpox and HIV: a Narrative Review

PURPOSE OF REVIEW

We reviewed the available literature on mpox in People with HIV (PWH). We highlight special considerations of mpox infection related to epidemiology, clinical presentation, diagnostic and treatment considerations, prevention, and public health messaging in PWH.

RECENT FINDINGS

During the 2022 mpox outbreak, PWH were disproportionally impacted worldwide. Recent reports suggest that the disease presentation, management, and prognosis of these patients, especially those with advanced HIV disease, can widely differ from those without HIV-associated immunodeficiency. Mpox can often be mild and resolve on its own in PWH with controlled viremia and higher CD4 counts. However, it can be severe, with necrotic skin lesions and protracted healing; anogenital, rectal, and other mucosal lesions; and disseminated organ systems involvement. Higher rates of healthcare utilization are seen in PWH. Supportive, symptomatic care and single or combination mpox-directed antiviral drugs are commonly used in PWH with severe mpox disease. Data from randomized clinical control trials on the efficacy of therapeutic and preventive tools against mpox among PWH are needed to better guide clinical decisions.

In vitro susceptibility of eighteen clinical isolates of human monkeypox virus to tecovirimat

BACKGROUND

In 2022, an outbreak of mpox that started in European countries spread worldwide through human-to-human transmission. Cases have been mostly mild, but severe clinical presentations have been reported. In these cases, tecovirimat has been the drug of choice to treat patients with aggravated disease.

OBJECTIVES

Here we investigated the tecovirimat susceptibility of 18 clinical isolates of monkeypox virus (MPXV) obtained from different regions of Brazil.

METHODS

Different concentrations of tecovirimat were added to cell monolayers infected with each MPXV isolate. After 72 hours, cells were fixed and stained for plaque visualization, counting, and measurement. The ortholog of F13L gene from each MPXV isolate was polymerase chain reaction (PCR)-amplified, sequenced, and the predicted protein sequences were analyzed.

FINDINGS

The eighteen MPXV isolates generated plaques of different sizes. Although all isolates were highly sensitive to the drug, two showed different response curves and IC50 values. However, the target protein of tecovirimat, F13 (VP37), was 100% conserved in all MPXV isolates and therefore does not explain the difference in sensitivity.

MAIN CONCLUSIONS

Our results support screening different MPXV isolates for tecovirimat susceptibility as an important tool to better use of the restricted number of tecovirimat doses available in low-income countries to treat patients with mpox.

Structure of monkeypox virus poxin: implications for drug design

Monkeypox, or mpox, is a disease that has recently resurfaced and spread across the globe. Despite the availability of an FDA-approved vaccine (JYNNEOS) and an effective drug (tecovirimat), concerns remain over the possible recurrence of a viral pandemic. Like any other virus, mpox virus must overcome the immune system to replicate. Viruses have evolved various strategies to overcome both innate and adaptive immunity. Poxviruses possess an unusual nuclease, poxin, which cleaves 2'-3'-cGAMP, a cyclic dinucleotide, which is an important second messenger in the cGAS-STING signaling pathway. Here, we present the crystal structure of mpox poxin. The structure reveals a conserved, predominantly β-sheet fold and highlights the high conservation of the cGAMP binding site and of the catalytic residues His17, Tyr138, and Lys142. This research suggests that poxin inhibitors could be effective against multiple poxviruses.

Pharmacological treatment and vaccines in monkeypox virus: a narrative review and bibliometric analysis

Mpox (earlier known as monkeypox) virus infection is a recognized public health emergency. There has been little research on the treatment options. This article reviews the specific drugs used to treat mpox virus infection and the vaccines used here. Instead of focusing on the mechanistic basis, this review narrates the practical, real-life experiences of individual patients of mpox virus disease being administered these medicines. We conducted a bibliometric analysis on the treatment of the mpox virus using data from several databases like PubMed, Scopus, and Embase. The research on this topic has grown tremendously recently but it is highly concentrated in a few countries. Cidofovir is the most studied drug. This is because it is indicated and also used off-label for several conditions. The drugs used for mpox virus infection include tecovirimat, cidofovir, brincidofovir, vaccinia immune globulin, and trifluridine. Tecovirimat is used most frequently. It is a promising option in progressive mpox disease in terms of both efficacy and safety. Brincidofovir has been associated with treatment discontinuation due to elevated hepatic enzymes. Cidofovir is also not the preferred drug, often used because of the unavailability of tecovirimat. Trifluridine is used topically as an add-on agent along with tecovirimat for ocular manifestations of mpox virus disease. No study reports individual patient data for vaccinia immune globulin. Though no vaccine is currently approved for mpox virus infection, ACAM 2000 and JYNNEOS are the vaccines being mainly considered. ACAM 2000 is capable of replicating and may cause severe adverse reactions. It is used when JYNNEOS is contraindicated. Several drugs and vaccines are under development and have been discussed alongside pragmatic aspects of mpox virus treatment and prevention. Further studies can provide more insight into the safety and efficacy of Tecovirimat in actively progressing mpox virus disease.

An Overview of Antivirals against Monkeypox Virus and Other Orthopoxviruses

The current monkeypox outbreaks during the COVID-19 pandemic have reignited interest in orthopoxvirus antivirals. Monkeypox belongs to the Orthopoxvirus genus of the Poxviridae family, which also includes the variola virus, vaccinia virus, and cowpox virus. Two orally bioavailable drugs, tecovirimat and brincidofovir, have been approved for treating smallpox infections. Given their human safety profiles and in vivo antiviral efficacy in animal models, both drugs have also been recommended to treat monkeypox infection. To facilitate the development of additional orthopoxvirus antivirals, we summarize the antiviral activity, mechanism of action, and mechanism of resistance of orthopoxvirus antivirals. This perspective covers both direct-acting and host-targeting antivirals with an emphasis on drug candidates showing in vivo antiviral efficacy in animal models. We hope to speed the orthopoxvirus antiviral drug discovery by providing medicinal chemists with insights into prioritizing proper drug targets and hits for further development.

Successful Outcome after Treatment with Cidofovir, Vaccinia, and Extended Course of Tecovirimat in a Newly-Diagnosed HIV Patient with Severe Mpox: A Case Report

Purpose: To report a case of severe mpox in a newly diagnosed HIV patient concerning for Immune Reconstitution Inflammatory Syndrome (IRIS) and/or tecovirimat resistance and to describe the management approach in the setting of refractory disease. Case: 49-year-old man presented with 2 weeks of perianal lesions. He tested positive for mpox PCR in the emergency room and was discharged home with quarantine instructions. Three weeks later, the patient returned with disseminated firm, nodular lesions in the face, neck, scalp, mouth, chest, back, legs, arms, and rectum, with worsening pain and purulent drainage from the rectum. The patient reported being on 3 days of tecovirimat treatment, which was prescribed by the Florida department of health (DOH). During this admission, he was found to be HIV positive. A pelvic CT scan revealed a 2.5 cm perirectal abscess. Treatment with tecovirimat was continued for 14 days, along with an empiric course of antibiotics for treatment of possible superimposed bacterial infection upon discharge. He was seen in the outpatient clinic and initiated antiretroviral therapy (ART) with TAF/emtricitabine/bictegravir. Two weeks after starting ART, the patient was readmitted for worsening mpox rash and rectal pain. Urine PCR also returned positive for chlamydia, for which the patient was prescribed doxycycline. He was discharged on a second course of tecovirimat and antibiotic therapy. Ten days later, the patient was readmitted for the second time due to worsening symptoms and blockage of the nasal airway from progressing lesions. At this point, there were concerns for tecovirimat resistance, and after discussion with CDC, tecovirimat was reinitiated for the third time, with the addition of Cidofovir and Vaccinia, and showed an improvement in his symptoms. He received three doses of cidofovir and two doses of Vaccinia, and the patient was then discharged to complete 30 days of tecovirimat. Outpatient follow-up showed favorable outcomes and near resolution. Conclusion: We reported a challenging case of worsening mpox after Tecovirimat treatment in the setting of new HIV and ART initiation concerning IRIS vs. Tecovirimat resistance. Clinicians should consider the risk of IRIS and weigh the pros and cons of initiating or delaying ART. In patients not responding to first-line treatment with tecovirimat, resistance testing should be performed, and alternative options should be considered. Future research is needed to establish guidance on the role of Cidofovir and Vaccinia immune globulin and the continuation of tecovirimat for refractory mpox.