Preparation of Monoclonal Antibodies Cross-Reactive with Orthopoxviruses and Their Application for Direct Immunofluorescence Test

Development of a specific MPXV antigen detection immunodiagnostic assay

Human monkeypox (mpox) has recently become a global public health emergency; however, assays that detect mpox infection are not widely available, largely due to cross-reactivity within the Orthopoxvirus genus. Immunoassay development was largely confined to researchers who focus on biothreats and endemic areas (Central and West Africa) until the 2022 outbreak. As was noted in the COVID-19 pandemic, antigen detection assays, integrated with molecular assays, are necessary to help curb the spread of disease. Antigen-detecting immunoassays offer the advantage of providing results ranging from within min to h and in lateral flow formats; they can be deployed for point-of-care, home, or field use. This study reports the development of an mpox-specific antigen detection immunoassay developed on a multiplexed, magnetic-bead-based platform utilizing reagents from all research sectors (commercial, academic, and governmental). Two semi-quantitative assays were developed in parallel and standardized with infectious mpox virus (MPXV) cell culture fluid and MPXV-positive non-human primate (NHP) sera samples. These assays could detect viral antigens in serum, were highly specific toward MPXV as compared to other infectious orthopoxviruses (vaccinia virus, cowpox virus, and camelpox virus), and exhibited a correlation with quantitative PCR results from an NHP study. Access to a toolbox of assays for mpox detection will be key for identifying cases and ensuring proper treatment, as MPXV is currently a global traveler.

Human monkeypox: A review of the literature

Monkeypox (MPX) has recently made international headlines for the rapid and simultaneous progression of the disease across the world. This review aims at summarizing the literature available as well as describing the evolution of the disease as it pertains to the cases today along with potential treatments and infection control strategies. To date, more than 76 countries have reported cases in more than 12,261 people. Before this, MPX was a rare zoonotic disease confined to endemic areas in Western and Central Africa with sporadic outbreaks namely in the United States, associated with the import of wild animals from Ghana. However, during the current outbreak, human-to-human transmission has become the primary mode of transmission, raising concerns for unaccounted community spread. Most of these patients did not travel to the endemic areas of Africa, suggesting possible previously underdetected community transmission. Observations from emergent cases have reported that the manifestations of the disease were sometimes atypical from what has been previously described. Young men who have sex with men seem to be the population most vulnerable to infection. Though the disease is currently perceived to be mild in its clinical course, questions that remain unclear and warrant further investigation include potential of humans harboring a genital reservoir of the virus and the possibility of airborne transmission, which has implications for infection control and health of the community at large.

Long-lasting immunity by early infection of maternal-antibody-protected infants

Newborn higher vertebrates are largely immuno-incompetent and generally survive infections--including poxviruses--by maternal antibody protection. Here, we show that mice survived epidemics as adults only if exposed to lethal orthopoxvirus infections during infancy under the umbrella of maternal protective antibodies. This implies that both the absence of exposure to infection during early infancy or of effective vaccination renders the population highly susceptible to new or old re-emerging pathogens.

Fast and reliable diagnostic methods for the detection of human poxvirus infections

Although the most prominent poxvirus, Variola virus, was successfully eradicated in the last century, several other poxviruses cause zoonotic infections that, in the early stages, resemble Variola virus infections with varying pathogenicity in humans. Over recent decades, numerous diagnostic methods for the detection of poxviruses have been established. As a result of technical progress and the advancement in molecular techniques, only a small selection of these methods meet the demands of being rapid and reliable. This review briefly introduces human poxviruses, summarizes the methods available, discusses their pros and cons and provides recommendations for a ‘fast and reliable diagnostic approach.

A PCR-based assay for detection of emerging vaccinia-like viruses isolated in Brazil

We report 2 strategies to identify Brazilian vaccinia virus (VACV) isolates related to Cantagalo virus (CTGV) based on the amplification of the hemagglutinin (HA) gene by the polymerase chain reaction (PCR). One PCR protocol was combined with restriction analysis using the endonuclease SnaB I, generating a unique digestion pattern for CTGV amplicons. The restriction profile could identify 41 CTGV-related isolates in 43 clinical specimens and clearly differentiated them from other orthopoxviruses and strains of VACV. Alternatively, we used a 1-step PCR assay with primers that specifically targeted CTGV HA sequence. This protocol produced similar results more rapidly than the 1st strategy, eliminating post-PCR procedures. The results were supported by Western blot analysis of the viral protein profile in infected cells. Both PCR-based methods enabled a fast, sensitive, and cost-effective detection of new isolates of VACV related to CTGV directly from clinical samples without requiring virus isolation.