Human antibody responses to circulating monkeypox virus emphasise the need for the first mpox-specific vaccine

Current status of next-generation vaccines against mpox virus: a scoping review

Introduction

The mpox disease, caused by the mpox virus (MPXV), has become a rising public health issue due to its potential to cause outbreaks. Consistently, this investigation aims to evaluate the current advances in the development of novel immunotherapeutic approaches against MPXV, which are crucial for preventing and controlling mpox spread.

Methods

This scoping review was performed by analyzing the content of English-language articles published between 2018 and 2024, which reported the development of next-generation vaccines against MPXV and their assessment in animal models. Patents within the scope of this research were also included. Contrarywise, studies based solely on immunoinformatic methods, reviews, book chapters, news, and others were excluded. The literature search was executed in 11 databases, such as Scopus, MEDLINE, and PubMed.

Results

A total of 36 records (32 studies and 4 patents) were included in this review. All 32 articles contain preclinical studies with varied group sizes (4-16) in which the main animal models were BALB/c mice. Less commonly used models included CAST/Ei mice and cynomolgus macaques. Moreover, most vaccines targeted one or more MPXV antigens, such as A29L, A35R, B6R, and M1R, through active immunization (via mRNAs or recombinant antigens) or passive immunization (antibody delivery).

Conclusion

Overall, new generation vaccines might represent prospective candidates to combat the mpox health concern. Nonetheless, several of the analyzed studies possess drawbacks, including animal models with limited similarity to humans, small group sizes, and brief follow-up durations. Consequently, additional research is required to ascertain the long-term protection, efficacy, and safety of these immunotherapeutic approaches.

Development and validation of a quantitative Orthopoxvirus immunoassay to evaluate and differentiate serological responses to Mpox infection and vaccination

BACKGROUND

The Mpox outbreak, caused by Monkeypox virus (MPXV), underscores the need for a serological assay to assess Mpox immunity. Modified Vaccinia Ankara (MVA) vaccine, an attenuated vaccinia virus (VACV), is authorised for Mpox prevention. We aimed to develop a quantitative immunoassay to differentiate infection- and vaccination-induced immunity and explore serological responses to Mpox infection and vaccination.

METHODS

We evaluated an electrochemiluminescence assay targeting IgG to 10 MPXV and 3 VACV antigens in plasma from adults in a cohort study with previous Mpox, MVA-vaccination, or historical controls. Sensitivity and specificity to distinguish i) seropositive versus naive and ii) infection- versus vaccination-induced seropositivity were determined using ROC curves. Antibody kinetics were analysed with generalised additive models.

FINDINGS

Eight of the thirteen IgG antibodies showed significant titre differences across groups identifying three key antigens: MPXVB6R, MPXVA27L, and VACVB5. A VACVB5 IgG titre of 0.082 IgG normalised units (nu) offered 74% (95% CI: 59-82%) sensitivity and 81% (73-96%) specificity for previous antigen exposure (infection or vaccine). For infection alone, an MPXVB6R IgG titre of 0.075 IgGnu provided 89% (82-98%) sensitivity and 94% (86-100%) specificity. To differentiate infection from vaccination-induced seropositivity, the sum of MPXVA27L IgG and the B6R/VACVB5 ratio provided 89% (80-96%) sensitivity and 80% (74-84%) specificity. VACVB5 IgG titres declined over time, with higher titres post-Mpox than post-vaccination (p < 0.0001).

INTERPRETATION

This assay demonstrates high sensitivity and specificity in quantifying and differentiating between antibody responses to Mpox infection and vaccination. Post-Mpox antibody responses were higher than post-vaccination, though both waned over time.

FUNDING

Health Research Board (MONKEYVAX-2022-1), University College Dublin School of Medicine.

Current advances and challenges in mpox vaccine development: a global landscape

Given the surge in mpox outbreaks in 2022 and the advancements in domestic and international vaccine research, the effectiveness of smallpox vaccines in providing cross-protection against mpox remains crucial. Having learned from the COVID-19 pandemic, it is significant to continue evaluating existing vaccines to ensure their safety and efficacy. Developing new vaccines for widespread use against mpox and its emerging strains also serves as a preventive strategy in the ongoing battle against this dynamic infection. Here's an opportunity to control human-to-human transmission, give short deadlines, and avoid vaccine disparity. Public health systems must take decisive action to prevent the global spread of mpox, particularly among vulnerable groups. This action should include strengthening global surveillance, improving vaccine access, and ensuring equitable distribution, particularly in resource-poor settings, to prevent future outbreaks. This review aims to assess recent advancements and barriers in mpox vaccine development, emphasizing cross-protection and equitable vaccine distribution in resource-poor settings.