The first workshop dedicated to Lassa virus–specific correlates of protection (CoP) was held in 2024 and was convened by the Coalition for Epidemic Preparedness Innovations (CEPI). Experts from multiple disciplines reviewed existing knowledge and identified gaps in understanding Lassa virus- and vaccine-induced immune responses. Discussions covered key areas including epidemiology, immunogenicity, preclinical and clinical research, data science, and regulatory considerations, with the goal of pinpointing opportunities to discover CoP.

Congenital cytomegalovirus (CMV) infection is the leading non-genetic cause of infant hearing loss worldwide, and a significant cause of neurodevelopmental disabilities. Reliance on polymerase chain reaction (PCR) for CMV DNA testing hampers diagnostic and research efforts in low-resource settings and universal screening implementation in high-resource settings. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated protein (Cas) detection and recombinase polymerase amplification (RPA) can be used together for low-cost viral detection. Here we describe an adaptable RPA-Cas12a assay for CMV DNA quantification based on the WHO international standard. Adequate quantification accuracy was achieved with contrived CMV samples but performance with Sierra Leonean infant saliva remains suboptimal. While improved quantification accuracy will require further optimization, our assay achieves screening test requirements, including > 80% sensitivity/specificity, quicker and more economically than PCR. This work highlights RPA-Cas12a-based assays for DNA quantification and suggests a path towards increased congenital CMV screening using PCR and RPA-Cas12a synergistically.

Lassa fever is a zoonotic disease endemic to several West African countries, with seasonal outbreaks and potential to cause future epidemics. Vaccines and other medical countermeasures are in development, requiring reliable assays for evaluation. A WHO International Standard (IS) for anti-Lassa virus (LASV) antibodies can support harmonization of serological assay results, aiding vaccine and therapeutic assessment, surrogates of protection identification, and improving epidemiological understanding. In this study, a pooled plasma sample from Lassa fever survivors was evaluated in a multi-centre collaborative study involving 17 laboratories for its suitability as a reference material for detecting anti-LASV antibodies. Additionally, two well-characterized monoclonal antibody (mAb) cocktails were assessed as potential alternatives to convalescent plasma. Expressing the antibody titre of the collaborative study panel samples relative to the convalescent plasma pool (NIBSC 20/202) or the mAb cocktails harmonized the results from the participants reducing the inter-laboratory variation. However, while the candidate IS 20/202 performed consistently across all assays, the mAb cocktails were not detected by a few binding antibody methods. These findings support the use of mAb cocktails as reference material for evaluating humoral responses within a laboratory or network using common assays; however, for an IS, applicable globally across methods, convalescent serum or plasma remains the most suitable material.

Steps should be taken now to prevent an epidemic of H5N1 in humans and prepare for an outbreak should it occur.

Evolution of SARS-CoV-2 from bat sarbecoviruses involved multiple changes in Spike in addition to insertion of the furin cleavage site (FCS). Analysis of the closely related Spike of BANAL-20-52 reveals key adaptations in the SARS-CoV-2 Spike beyond the FCS that occurred prior to the spillover of SARS-CoV-2's immediate progenitor to humans. Bat sarbecoviruses have enteric tropism and spread mostly by the gastrointestinal route. Their Spike proteins predominantly assume the locked form, which is able to resist the low pH of the bat gastrointestinal tract. Initial changes during the SARS-CoV-2 evolutionary pathway included substitutions that expanded the host range of the sarbecovirus progenitor and allowed circulation in nonbat mammals. Adaptation of the SARS-CoV-2 progenitors also involved remodeling of the amino-terminal domain. Respiratory adaptation occurred during circulation in nonbat animals and resulted in greater propensity for Spike to assume open forms that are less compact and more metastable than the locked or closed forms. Substitutions at monomer interfaces in the Spike trimer facilitate the open shift. Like FCS insertion, these substitutions make Spike more susceptible to low pH degradation and could not have occurred in bats. After SARS-CoV-2 spilled over to humans Spikes of the dominant lineage acquired an aspartic acid to glycine substitution at position 614 that further decreases interaction between monomers and promotes opening of the Spike trimer. A multi-stage evolutionary trajectory is also evident during cross-species transmissions of bat sarbecoviruses to pangolins and the first known spillovers of SARS-CoV via the wildlife trade.

BACKGROUND:Lassa fever, caused by Lassa mammarenavirus (LASV), is a rodent-borne disease endemic to west Africa. Zoonotic surveillance of LASV provides epidemiological insights into its potential presence. We aimed to assess LASV antigen and antibody prevalence in peri-domestic rodents in southeastern Sierra Leone. METHODS:In this cross-sectional study, small mammal trapping was conducted in Kenema District, Sierra Leone, from Nov 8, 2018 to July 10, 2019. LASV antigen was detected with a nucleoprotein antigen rapid diagnostic test at necropsy, then compared with gold-standard quantitative RT-PCR in a subset of specimens to assess specificity and sensitivity. LASV IgG antibodies against nucleoprotein and glycoprotein were tested using a semi-quantitative ELISA in Mastomys and Rattus species. FINDINGS:Of the 373 specimens tested, 74 (20%) were positive for LASV antigen. Compared with qRT-PCR, antigen testing showed a specificity of 61·9% (95% CI 52·5-70·6) and sensitivity of 100·0% (95% CI 2·5-100·0%). 40 (11%) specimens tested positive for LASV nucleoprotein-specific IgG, whereas an additional 12 (3%) were only positive for LASV glycoprotein-specific IgG, respectively. Simultaneous antigen and IgG antibody presence was observed in some Mastomys sp specimens (odds ratio 0·43 [95% CI 0·24-0·73], p=0·0011). However, the relative strength of antigen response did not explain the variability in the IgG response to either glycoprotein (ρ 0·04 [95% CI -0·34 to 0·41], p=0·85) or nucleoprotein (ρ -0·23 [95% CI -0·52 to 0·11], p=0·17). INTERPRETATION:Although further evaluation is needed, the tools used in this study can aid in generating valuable public health data for LASV surveillance and in prioritising specimens for further downstream analyses. FUNDING:National Institute of Allergy and Infectious Diseases of the National Institutes of Health.

INTRODUCTION:The 2013-2016 Western African outbreak of the Ebola virus disease (EVD), the largest recorded outbreak since the discovery of Ebola virus (EBOV) in 1976, destabilised local health systems and left thousands of survivors at risk for postacute sequelae, including vision-threatening uveitis. In an EVD survivor with severe panuveitis, the detection of persistent EBOV in the aqueous humour, long after clearance of acute viremia, focused clinical and research attention on the host-EBOV interaction in the unique terrain of ocular immune privilege. Despite the recognition that uveitis is common and consequential in EVD survivors, our understanding of pathogenesis is extremely limited, including the contributions of viral persistence and ocular-specific and systemic immune responses to disease expression. In this study protocol, we outline a multifaceted approach to characterise EVD-associated intraocular inflammation, including the clinical phenotype and complications; the presence of EBOV (or EBOV RNA/antigen) in ocular fluids and tissues; and associated local ocular-specific and peripheral immune responses. METHODS AND ANALYSIS:We use an observational cohort design, which includes EVD survivors and close contacts of EVD survivors (ie, no documented history of EVD), and we propose disease (clinical examination and imaging), as well as molecular, virologic and immunologic characterisation, to meet research objectives. ETHICS AND DISSEMINATION:This study has received Institutional Review Board approval from University of Nebraska Medical Centre, Emory University and Sierra Leone Ministry of Health. Findings will be disseminated through peer-reviewed publications.

Lassa virus (LASV) is a World Health Organization (WHO) priority pathogen that causes high morbidity and mortality. Recently, we showed that a combination of three broadly neutralizing human monoclonal antibodies known as Arevirumab-3 (8.9F, 12.1F, 37.2D) based on the lineage IV Josiah strain protected 100% of cynomolgus macaques against heterologous challenge with lineage II and III strains of LASV when therapy was initiated beginning at day 8 after challenge. LASV strains from Benin and Togo represent a new lineage VII that are more genetically diverse from lineage IV than strains from lineages II and III. Here, we tested the ability of Arevirumab-3 to protect macaques against a LASV lineage VII Togo isolate when treatment was administered beginning 8 days after exposure. Unexpectedly, only 40% of treated animals survived challenge. In a subsequent study we showed that Arevirumab-3 protected 100% of macaques from lethal challenge when treatment was initiated 7 days after LASV Togo exposure. Based on our transcriptomics data, successful Arevirumab-3 treatment correlated with diminished neutrophil signatures and the predicted development of T cell responses. As the in vitro antiviral activity of Arevirumab-3 against LASV Togo was equivalent to lineage II and III strains, the reduced protection in macaques against Togo likely reflects the faster disease course of LASV Togo in macaques than other strains. This data causes concern regarding the ability of heterologous vaccines and treatments to provide cross protection against lineage VII LASV isolates.

Ebola virus (EBOV) infection results in Ebola virus disease (EVD), an often severe disease with a nonspecific presentation. Since its recognition, periodic outbreaks of EVD continue to occur in sub-Saharan Africa. The 2013-2016 West African EVD outbreak was the largest recorded, resulting in a substantial cohort of EVD survivors with persistent health complaints and variable immune responses. In this study, we characterize humoral immune responses in EVD survivors and their contacts in Eastern Sierra Leone. We found high levels of EBOV IgG in EVD survivors and lower yet substantial antibody levels in household contacts, suggesting subclinical transmission. Neutralizing antibody function was prevalent but variable in EVD survivors, raising questions about the durability of immune responses from natural infection with EBOV. Additionally, we found that certain discrete symptoms-ophthalmologic and auditory-are associated with EBOV IgG seropositivity, while an array of symptoms are associated with the presence of neutralizing antibody. We measured Ebola virus-specific IgG antibody and antibody neutralization potential in a cohort of 357 Ebola virus disease survivors and 969 contacts. We found that Ebola virus IgG and antibody neutralization potential persisted in the survivor population but was variable across the cohort.

In the United States (US), biosafety and biosecurity oversight of research on viruses is being reappraised. Safety in virology research is paramount and oversight frameworks should be reviewed periodically. Changes should be made with care, however, to avoid impeding science that is essential for rapidly reducing and responding to pandemic threats as well as addressing more common challenges caused by infectious diseases. Decades of research uniquely positioned the US to be able to respond to the COVID-19 crisis with astounding speed, delivering life-saving vaccines within a year of identifying the virus. We should embolden and empower this strength, which is a vital part of protecting the health, economy, and security of US citizens. Herein, we offer our perspectives on priorities for revised rules governing virology research in the US.

Infection with Lassa virus (LASV) can cause Lassa fever, a haemorrhagic illness with an estimated fatality rate of 29.7%, but causes no or mild symptoms in many individuals. Here, to investigate whether human genetic variation underlies the heterogeneity of LASV infection, we carried out genome-wide association studies (GWAS) as well as seroprevalence surveys, human leukocyte antigen typing and high-throughput variant functional characterization assays. We analysed Lassa fever susceptibility and fatal outcomes in 533 cases of Lassa fever and 1,986 population controls recruited over a 7 year period in Nigeria and Sierra Leone. We detected genome-wide significant variant associations with Lassa fever fatal outcomes near GRM7 and LIF in the Nigerian cohort. We also show that a haplotype bearing signatures of positive selection and overlapping LARGE1, a required LASV entry factor, is associated with decreased risk of Lassa fever in the Nigerian cohort but not in the Sierra Leone cohort. Overall, we identified variants and genes that may impact the risk of severe Lassa fever, demonstrating how GWAS can provide insight into viral pathogenesis. GWAS in difficult-to-recruit populations identifies variants associated with Lassa fever outcome and susceptibility at loci proximal to LIF, GRM7 and LARGE1.