Identification of Tecovirimat Resistance-Associated Mutations in Human Monkeypox Virus - Los Angeles County

Identification of mpox M1R and B6R monoclonal and bispecific antibodies that efficiently neutralize authentic mpox virus

In 2022, the monkeypox virus (mpox virus, MPXV) exhibited global dissemination across six continents, representing a notable challenge owing to the scarcity of targeted antiviral interventions. Passive immunotherapy, such as the use of monoclonal antibodies (mAbs) and bispecific antibodies (bsAbs), has emerged as a promising option for antiviral regimens. Here, we generated several mAbs against M1R and B6R of MPXV, and subsequently characterized the antiviral activity of these antibodies both in vitro and in vivo. Two neutralizing mAbs, M1H11 and M3B2, targeting M1R, and one B6R-specific mAb, B7C9, were identified. They exhibited varying antiviral efficacy against vaccinia virus (VACV) in vitro and in vivo. A cocktail comprising M1H11 and M3B2 demonstrated a superior protective effect in vivo. A bsAb, Bis-M1M3, was engineered by conjugating the fragment crystallizable (Fc) region of the human-mouse chimeric engineered M1H11 with the single-chain fragment variable (scFv) of M3B2. In mice challenged with MPXV, Bis-M1M3 showed a notable protective effects. Analysis of neutralization mechanism showed that these mAbs and Bis-M1M3 exerted virus-neutralizing effects before the virus infects cells. In vivo pharmacokinetic experiments showed that Bis-M1M3 has a long half-life in rhesus macaques. This study provides crucial insights for further research on broad-spectrum antiviral drugs against MPXV and other orthopoxviruses.

Severe mpox in an immunocompromised patient complicated by deep tissue infection: A case report

Objectives

We report prolonged mpox (>14 weeks) in a patient with HIV complicated by deep tissue MPXV infection despite two courses of tecovirimat treatment.

Methods

MPXV-DNA levels in lesional swabs, blood and tissue were quantified by qPCR. Anti-MPXV antibodies were analyzed by IF and VNT. Infectivity was assessed by virus isolation. Sequencing was performed to assess for tecovirimat resistance mutations and quantitative results were obtained by digital SNP PCR (A288P).

Results

The patient's clinical condition improved significantly during both tecovirimat treatment courses (each 14 days), yet we observed persistent MPXV-DNA in lesions accompanied by viremia (mean 1.4 × 104 copies/ml) for >14 weeks. A deep tissue infection driven by MPXV complicated the clinical course (week 9). Presence of infectious virus within the tissue and high infectious titers (>106 PFU/ml) were observed. The VP37 protein sequence revealed A288P substitutions. Digital PCR showed 1 % and less abundance (A288P) during first treatment course (blood and swabs), with increasing proportion during second course (week 8-9; 28 % in blood and swabs), however the mutation was absent in samples from deep tissue infection and MPXV isolates (week 9) indicating compartimentalization. Morphological fully enveloped MPXV partices visualized by TEM in necrotic areas suggesting tecovirimat treatment failure in the deep tissue compartment.

Conclusion

Our data provide evidence that Tecovirimat treatment selects for compartimentalized viral mutations (A288P). While the patient clinically benefited from repeated tecovirimat course, emergence of viral muations and deep tissue infection emphasizes the challenge and importance of infectious disease monitoring in mpox patient management.

Notes from the Field: Mpox Cluster Caused by Tecovirimat-Resistant Monkeypox Virus - Five States, October 2023-February 2024

The antiviral drug tecovirimat* has been used extensively to treat U.S. mpox cases since the start of a global outbreak in 2022. Mutations in the mpox viral protein target (F13 or VP37) that occur during treatment can result in resistance to tecovirimat† (1,2). CDC and public health partners have conducted genetic surveillance of monkeypox virus (MPXV) for F13 mutations through sequencing and monitoring of public databases. MPXV F13 mutations associated with resistance have been reported since 2022, typically among severely immunocompromised mpox patients who required prolonged courses of tecovirimat (3-5). A majority of patients with infections caused by MPXV with resistant mutations had a history of tecovirimat treatment; however, spread of tecovirimat-resistant MPXV was reported in California during late 2022 to early 2023 among persons with no previous tecovirimat treatment (3). This report describes a second, unrelated cluster of tecovirimat-resistant MPXV among 18 persons with no previous history of tecovirimat treatment in multiple states.

Mpox Recurrence and Tecovirimat Resistance in a Patient With Advanced Human Immunodeficiency Virus Disease

We present a case of mpox recurrence in a transgender woman with AIDS. Her recurrent lesions required several courses of antiviral therapy over a 5-month period and her monkeypox viral genome was subsequently noted to have tecovirimat resistance mutations. Interestingly, she developed a robust orthopoxvirus-specific T-cell response.

Investigation of an Mpox Outbreak Affecting Many Vaccinated Persons in Chicago, Illinois-March 2023-June 2023

BACKGROUND

After months of few mpox cases, an increase in cases was reported in Chicago during May 2023, predominantly among fully vaccinated (FV) patients. We investigated the outbreak scope, differences between vaccinated and unvaccinated patients, and hypotheses for monkeypox virus (MPXV) infection after vaccination.

METHODS

We interviewed patients and reviewed medical records to assess demographic, behavioral, and clinical characteristics; mpox vaccine status; and vaccine administration routes. We evaluated serum antibody levels after infection and compared patient viral genomes with MPXV sequences in available databases. We discussed potential vaccine compromise with partners who manufactured, handled, and administered the vaccine associated with breakthrough infections.

RESULTS

During 18 March-27 June 2023, we identified 49 mpox cases; 57% of these mpox patients were FV. FV patients received both JYNNEOS doses subcutaneously (57%), intradermally (7%), or via heterologous administration (36%). FV patients had more median sex partners (3; interquartile range [IQR] = 1-4) versus not fully vaccinated patients (1; IQR = 1-2). Thirty-six of 37 sequenced specimens belonged to lineage B.1.20 of clade IIb MPXV, which did not demonstrate any amino acid changes relative to B.1, the predominant lineage from May 2022. Vaccinated patients demonstrated expected humoral antibody responses; none were hospitalized. No vaccine storage excursions were identified. Approximately 63% of people at risk for mpox in Chicago were FV during this period.

CONCLUSIONS

Our investigation indicated that cases were likely due to frequent behaviors associated with mpox transmission, even with relatively high vaccine effectiveness and vaccine coverage. Cases after vaccination might occur in similar populations.

Severe mpox requiring colostomy in a patient with advanced HIV disease: A case report and literature review

This severe monkeypox case described a 23-year-old male with advanced HIV-1 disease presenting perirectal abscess, extensive anal ulcerative lesions requiring colostomy, and tecovirimat resistance. Radiologically non-liquefied perirectal abscess presented diagnostic challenges highlighting the complexity of aggressive monkeypox manifestations in immunocompromised individuals.

Bisbenzimide compounds inhibit the replication of prototype and pandemic potential poxviruses

We previously identified the bisbenzimide Hoechst 33342 (H42) as a potent multi-stage inhibitor of the prototypic poxvirus, the vaccinia virus (VACV), and several parapoxviruses. A recent report showed that novel bisbenzimide compounds similar in structure to H42 could prevent human cytomegalovirus replication. Here, we assessed whether these compounds could also serve as poxvirus inhibitors. Using virological assays, we show that these bisbenzimide compounds inhibit VACV spread, plaque formation, and the production of infectious progeny VACV with relatively low cell toxicity. Further analysis of the VACV lifecycle indicated that the effective bisbenzimide compounds had little impact on VACV early gene expression but inhibited VACV late gene expression and truncated the formation of VACV replication sites. Additionally, we found that bisbenzimide compounds, including H42, can inhibit both monkeypox and a VACV mutant resistant to the widely used anti-poxvirus drug TPOXX (Tecovirimat). Therefore, the tested bisbenzimide compounds were inhibitors of both prototypic and pandemic potential poxviruses and could be developed for use in situations where anti-poxvirus drug resistance may occur. Additionally, these data suggest that bisbenzimide compounds may serve as broad-activity antiviral compounds, targeting diverse DNA viruses such as poxviruses and betaherpesviruses.IMPORTANCEThe 2022 mpox (monkeypox) outbreak served as a stark reminder that due to the cessation of smallpox vaccination over 40 years ago, most of the human population remains susceptible to poxvirus infection. With only two antivirals approved for the treatment of smallpox infection in humans, the need for additional anti-poxvirus compounds is evident. Having shown that the bisbenzimide H33342 is a potent inhibitor of poxvirus gene expression and DNA replication, here we extend these findings to include a set of novel bisbenzimide compounds that show anti-viral activity against mpox and a drug-resistant prototype poxvirus mutant. These results suggest that further development of bisbenzimides for the treatment of pandemic potential poxviruses is warranted.

Challenges in Managing Treatment-Resistant Mpox Complicated by Severe Superinfection

Though typically self-limiting, severe mpox infections have been treated with antiviral medications, most notably tecovirimat. Various reports exist of mpox progression despite tecovirimat treatment. Treatment resistance can be due to acquired mpox strain mutations, most often occurring in an immunocompromised host. We present the case of a male with AIDS who developed disseminated treatment-resistant mpox infection complicated by superimposed bacterial and fungal infections. His orthopoxvirus polymerase chain reaction result remained positive despite treatment with 4 weeks of oral tecovirimat and 3 doses of intravenous cidofovir. Poor response to antiviral therapy was likely due to his underlying immunocompromised state; however, strain resistance cannot be ruled out given that the patient had started but not completed a 14-day course of tecovirimat 8 months prior, at the time of initial mpox diagnosis. Patients with mpox who are immunocompromised may require extended and additional treatment beyond the standard 14 days of tecovirimat, such as cidofovir, brincidofovir, or intravenous vaccina immune globulin.

Surveillance of Complicated Mpox Cases Unresponsive to Oral Tecovirimat in Los Angeles County, 2022

The Los Angeles County Department of Public Health established a surveillance system to identify complicated (advanced human immunodeficiency virus [HIV] or hospitalized) mpox cases. From 1 August to 30 November 2022, we identified 1581 mpox cases, of which 134 (8.5%) were complicated. A subset of 8 cases did not recover after either initiating or completing a course of oral tecovirimat. All 8 patients were HIV positive and had advanced HIV (CD4 count <200 cells/μL). We identified 8 distinct mutations previously associated with tecovirimat resistance in specimens collected from 6 patients. Ongoing surveillance of viral evolution requires close coordination between health departments and frontline providers.

How the Orthodox Features of Orthopoxviruses Led to an Unorthodox Mpox Outbreak: What We've Learned, and What We Still Need to Understand

Orthopoxviruses have repeatedly confounded expectations in terms of the clinical illness they cause and their patterns of spread. Monkeypox virus (MPXV), originally characterized in the late 1950s during outbreaks among captive primates, has been recognized since the 1970s to cause human disease (mpox) in West and Central Africa, where interhuman transmission has largely been associated with nonsexual, close physical contact. In May 2022, a focus of MPXV transmission was detected, spreading among international networks of gay, bisexual, and other men who have sex with men. The outbreak grew in both size and geographic scope, testing the strength of preparedness tools and public health science alike. In this article we consider what was known about mpox before the 2022 outbreak, what we learned about mpox during the outbreak, and what continued research is needed to ensure that the global public health community can detect, and halt further spread of this disease threat.

Pathology and Monkeypox virus Localization in Tissues From Immunocompromised Patients With Severe or Fatal Mpox

BACKGROUND

Pathology and Monkeypox virus (MPXV) tissue tropism in severe and fatal human mpox is not thoroughly described but can help elucidate the disease pathogenesis and the role of coinfections in immunocompromised patients.

METHODS

We analyzed biopsy and autopsy tissues from 22 patients with severe or fatal outcomes to characterize pathology and viral antigen and DNA distribution in tissues by immunohistochemistry and in situ hybridization. Tissue-based testing for coinfections was also performed.

RESULTS

Mucocutaneous lesions showed necrotizing and proliferative epithelial changes. Deceased patients with autopsy tissues evaluated had digestive tract lesions, and half had systemic tissue necrosis with thrombotic vasculopathy in lymphoid tissues, lung, or other solid organs. Half also had bronchopneumonia, and one-third had acute lung injury. All cases had MPXV antigen and DNA detected in tissues. Coinfections were identified in 5 of 16 (31%) biopsy and 4 of 6 (67%) autopsy cases.

CONCLUSIONS

Severe mpox in immunocompromised patients is characterized by extensive viral infection of tissues and viremic dissemination that can progress despite available therapeutics. Digestive tract and lung involvement are common and associated with prominent histopathological and clinical manifestations. Coinfections may complicate mpox diagnosis and treatment. Significant viral DNA (likely correlating to infectious virus) in tissues necessitates enhanced biosafety measures in healthcare and autopsy settings.

Prolonged viral shedding in an immunocompromised Korean patient infected with hMPXV, sub-lineage B.1.3, with acquired drug resistant mutations during tecovirimat treatment

Following the worldwide surge in mpox (monkeypox) in 2022, cases have persisted in Asia, including South Korea, and sexual contact is presumed as the predominant mode of transmission, with a discernible surge in prevalence among immunocompromised patients. Drugs such as tecovirimat can result in drug-resistant mutations, presenting obstacles to treatment. This study aimed to ascertain the presence of tecovirimat-related resistant mutations through genomic analysis of the monkeypox virus isolated from a reported case involving prolonged viral shedding in South Korea. Here, tecovirimat-resistant mutations, previously identified in the B.1 clade, were observed in the B.1.3 clade, predominant in South Korea. These mutations exhibited diverse patterns across different samples from the same patient and reflected the varied distribution of viral subpopulations in different anatomical regions. The A290V and A288P mutant strains we isolated hold promise for elucidating these mechanisms, enabling a comprehensive analysis of viral pathogenesis, replication strategies, and host interactions. Our findings imply that acquired drug-resistant mutations, may present a challenge to individual patient treatment. Moreover, they have the potential to give rise to transmitted drug-resistant mutations, thereby imposing a burden on the public health system. Consequently, the meticulous genomic surveillance among immunocompromised patients, conducted in this research, assumes paramount importance.

Clinical considerations on monkeypox antiviral medications: An overview

Monkeypox (mpox), a virus belonging to the orthopoxvirus family, can cause a zoonotic infectious disease with morbidity and cosmetic complications. Therefore, effective antiviral drugs with appropriate safety profiles are important for the treatment of patients with mpox. To date, there is no FDA-approved drug for the treatment of mpox. However, tecovirimat, brincidofovir, and cidofovir are the candidate therapies for the management of mpox. Given the safety concerns following the use of these medications, we aimed to review evidence on the clinical considerations of mpox antiviral medications that will be useful to guide clinicians in the treatment approach. Based on the current evidence, tecovirimat has favorable clinical efficacy, safety, and side effect profile and it can be considered as first-line treatment for mpox.

Trifluridine for treatment of mpox infection in drug combinations in ophthalmic cell models

The Mpox virus can cause severe disease in the susceptible population with dermatologic and systemic manifestations. Furthermore, ophthalmic manifestations of mpox infection are well documented. Topical trifluridine (TFT) eye drops have been used for therapy of ophthalmic mpox infection in patients, however, its efficacy against mpox virus infection in this scenario has not been previously shown. In the present study, we have established ophthalmic cell models suitable for the infection with mpox virus. We show, that TFT is effective against a broad range of mpox isolates in conjunctival epithelial cells and keratocytes. Further, TFT remained effective against a tecovirimat-resistant virus strain. In the context of drug combinations, a nearly additive effect was observed for TFT combinations with brincidofovir and tecovirimat in conjunctival epithelial cells, while a slight antagonism was observed for both combinations in keratocytes. Altogether, our findings demonstrate TFT as a promising drug for treatment of ophthalmic mpox infection able to overcome tecovirimat resistance. However, conflicting results regarding the effect of drug combinations with approved compounds warrant close monitoring of such use in patients.

Tecovirimat Resistance in Mpox Patients, United States, 2022-2023

During the 2022 multinational outbreak of monkeypox virus (MPXV) infection, the antiviral drug tecovirimat (TPOXX; SIGA Technologies, Inc., https://www.siga.com) was deployed in the United States on a large scale for the first time. The MPXV F13L gene homologue encodes the target of tecovirimat, and single amino acid changes in F13 are known to cause resistance to tecovirimat. Genomic sequencing identified 11 mutations previously reported to cause resistance, along with 13 novel mutations. Resistant phenotype was determined using a viral cytopathic effect assay. We tested 124 isolates from 68 patients; 96 isolates from 46 patients were found to have a resistant phenotype. Most resistant isolates were associated with severely immunocompromised mpox patients on multiple courses of tecovirimat treatment, whereas most isolates identified by routine surveillance of patients not treated with tecovirimat remained sensitive. The frequency of resistant viruses remains relatively low (<1%) compared with the total number of patients treated with tecovirimat.

Treatment of Mpox with Suspected Tecovirimat Resistance in Immunocompromised Patient, United States, 2022

Reports of tecovirimat-resistant mpox have emerged after widespread use of antiviral therapy during the 2022 mpox outbreak. Optimal management of patients with persistent infection with or without suspected resistance is yet to be established. We report a successfully treated case of severe mpox in California, USA, that had suspected tecovirimat resistance.

Mpox and HIV-Collision of Two Diseases

PURPOSE OF REVIEW

The global outbreak of mpox has brought renewed attention to a previously neglected disease which is particularly severe in people with underlying untreated HIV co-infection. For this population, the disease is progressive, severe, and often lethal. In this review, we examine the pathogenesis of mpox disease and its collision with co-existent HIV infection and discuss key considerations for management as well as emerging clinical dilemmas and areas for future research.

RECENT FINDINGS

Co-existent untreated HIV infection characterized by severe immunocompromise potentiates the nefarious effects of monkeypox virus infection leading to severe manifestations of mpox. Treating mpox in the context of HIV requires mpox-directed therapies, supportive care, and HIV-specific treatment to restore immune function. Preventative measures for PWH are like those in healthy individuals, but the effectiveness and durability of protection conferred by existing vaccines in PWH remain to be fully characterized. Mpox is an important opportunistic infection in PWH. Clinicians should be aware of the unique features of the disease in this population and approaches to care and management of mpox in PWH.

Differences in pathogenicity among the mpox virus clades: impact on drug discovery and vaccine development

Since May 2022, mpox virus (MPXV) has attracted considerable attention due to a multi-country outbreak. Marked differences in epidemiology, transmission, and pathology between the 2022 global mpox outbreak (clade IIb) and classical mpox disease, endemic in Africa (clades I and IIa) have been highlighted. MPXV genome analysis has identified the genomic changes characterizing clade IIb and the drivers of MPXV rapid evolution. Although mpox cases have largely declined, MPXV cryptic transmission and microevolution continues, which may lead to an MPXV of unpredictable pathogenicity. Vaccines and antivirals developed against variola virus, the agent that caused the extinguished plague smallpox, have been used to contain the 2022 mpox outbreak. In this review article, recent findings on MPXV origin and evolution and relevant models able to recapitulate differences in MPXV pathogenicity, which are important for drug and vaccine development, are discussed.

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.