Post-exposure intranasal IFNα suppresses replication and neuroinvasion of Venezuelan Equine Encephalitis virus within olfactory sensory neurons.

BACKGROUND: Venezuelan Equine Encephalitis virus (VEEV) may enter the central nervous system (CNS) within olfactory sensory neurons (OSN) that originate in the nasal cavity after intranasal exposure. While it is known that VEEV has evolved several mechanisms to inhibit type I interferon (IFN) signaling within infected cells, whether this inhibits virologic control during neuroinvasion along OSN has not been studied. METHODS: We utilized an established murine model of intranasal infection with VEEV and a repository of scRNAseq data from IFN-treated OSN to assess the cellular targets and IFN signaling responses after VEEV exposure. RESULTS: We found that immature OSN, which express higher levels of the VEEV receptor LDLRAD3 than mature OSN, are the first cells infected by VEEV. Despite rapid VEEV neuroinvasion after intranasal exposure, olfactory neuroepithelium (ONE) and olfactory bulb (OB) IFN responses, as assessed by evaluation of expression of interferon signaling genes (ISG), are delayed for up to 48 h during VEEV neuroinvasion, representing a potential therapeutic window. Indeed, a single intranasal dose of recombinant IFNα triggers early ISG expression in both the nasal cavity and OB. When administered at the time of or early after infection, IFNα treatment delayed onset of sequelae associated with encephalitis and extended survival by several days. VEEV replication after IFN treatment was also transiently suppressed in the ONE, which inhibited subsequent invasion into the CNS. CONCLUSIONS: Our results demonstrate a critical and promising first evaluation of intranasal IFNα for the treatment of human encephalitic alphavirus exposures.

An improved alphaviruses-specific RT-qPCR facilitates monitoring and prevention of alphaviruses.

Molecular surveillance is vital for monitoring arboviruses, often employing genus-specific quantitative reverse-transcription polymerase chain reaction (RT-qPCR). Despite this, an overlooked chikungunya fever outbreak occurred in Yunnan province, China, in 2019 and false negatives are commonly encountered during alphaviruses screening practice, highlighting the need for improved detection methods. In this study, we developed an improved alphaviruses-specific RT-qPCR capable of detecting chikungunya virus, eastern equine encephalitis virus, western equine encephalitis virus, Venezuelan equine encephalitis virus, Sindbis virus, Mayaro virus, and Ross River virus with high sensitivity and specificity. The assay identified three chikungunya virus-positive cases out of 188 sera retrospectively. Later genetic characterization suggested that imported cases from neighboring countries may be responsible for the neglected chikungunya fever outbreak of 2019 in Yunnan. Our findings underscore the value of improved alphaviruses-specific RT-qPCR in bolstering alphaviruses surveillance and informing preventive strategies.

Therapeutic efficacy of a potent anti-Venezuelan equine encephalitis virus antibody is contingent on Fc effector function.

The development of specific, safe, and potent monoclonal antibodies (Abs) has led to novel therapeutic options for infectious disease. In addition to preventing viral infection through neutralization, Abs can clear infected cells and induce immunomodulatory functions through engagement of their crystallizable fragment (Fc) with complement proteins and Fc receptors on immune cells. Little is known about the role of Fc effector functions of neutralizing Abs in the context of encephalitic alphavirus infection. To determine the role of Fc effector function in therapeutic efficacy against Venezuelan equine encephalitis virus (VEEV), we compared the potently neutralizing anti-VEEV human IgG F5 (hF5) Ab with intact Fc function (hF5-WT) or containing the loss of function Fc mutations L234A and L235A (hF5-LALA) in the context of VEEV infection. We observed significantly reduced binding to complement and Fc receptors, as well as differential in vitro kinetics of Fc-mediated cytotoxicity for hF5-LALA compared to hF5-WT. The in vivo efficacy of hF5-LALA was comparable to hF5-WT at -24 and + 24 h post infection, with both Abs providing high levels of protection. However, when hF5-WT and hF5-LALA were administered + 48 h post infection, there was a significant decrease in the therapeutic efficacy of hF5-LALA. Together these results demonstrate that optimal therapeutic Ab treatment of VEEV, and possibly other encephalitic alphaviruses, requires neutralization paired with engagement of immune effectors via the Fc region.

A framework for automated scalable designation of viral pathogen lineages from genomic data.

Pathogen lineage nomenclature systems are a key component of effective communication and collaboration for researchers and public health workers. Since February 2021, the Pango dynamic lineage nomenclature for SARS-CoV-2 has been sustained by crowdsourced lineage proposals as new isolates were sequenced. This approach is vulnerable to time-critical delays as well as regional and personal bias. Here we developed a simple heuristic approach for dividing phylogenetic trees into lineages, including the prioritization of key mutations or genes. Our implementation is efficient on extremely large phylogenetic trees consisting of millions of sequences and produces similar results to existing manually curated lineage designations when applied to SARS-CoV-2 and other viruses including chikungunya virus, Venezuelan equine encephalitis virus complex and Zika virus. This method offers a simple, automated and consistent approach to pathogen nomenclature that can assist researchers in developing and maintaining phylogeny-based classifications in the face of ever-increasing genomic datasets.

First detection of Rio Negro virus (Venezuelan equine encephalitis complex subtype VI) in Córdoba, Argentina

Rio Negro virus (RNV) (Venezuelan equine encephalitis subtype VI) circulates only in Argentina; in northern provinces, isolates have been obtained from mosquitoes and rodents since 1980 and have been associated with acute febrile illness in humans. However, no studies of RNV have been performed in the central area of the country. We carried out molecular and serological detection of RNV in Córdoba, a province of the central part of the country, in mosquitoes and humans, respectively. One mosquito pool tested positive for alphavirus RNA by reverse transcriptase-nested polymerase chain reaction (RT-nested PCR). Subsequent sequencing determined that this alphavirus grouped with RNV. Serological studies detected antibodies to RNV in one human serum sample, which was obtained during the same period that RNV was detected using the aforementioned molecular methods. This is the first report of RNV circulation in the central area of Argentina, indicating an expansion of its original distribution. These results highlight the importance of strengthening surveillance procedures in endemic areas, as well as in new regions where RNV may emerge.

Prevalencia de anticuerpos VEE y EEE en población humana y equina de la selva peruana / Prevalence of antibodies VEE and EEE in human and equine population of the Peruvian jungle

El complejo de virus de encefalitis equina venezolana (VEE) esta integrado por los serotipos antigénicos 1AB, 1C,1D,1E de los cuales los únicos relacionados con epizootias son los serotipos 1 AB y IC. En el Perú el virus epizootico ha hecho su aparición esporádica desde la década de los 30, siendo la última incursión epizoodémica en el año 1973 por el serotipo 1AB. En Loreto, departamento de la Selva peruana, durante 1973 se identificó el serotipo 1D enzootico, asociado a cuadros febriles en humanos, sin embargo encuestas serológicas previas muestran anticuerpos VEE, entendiéndose que su presencia tiene una antigüedad pasada no determinada. El estudio tiene la finalidad de comparar la magnitud de la circulación de las cepas selváticas de la VEE en humanos y equinos, principalmente en las áreas tropicales donde hay una significativa población equina, considerándose este hecho de riesgo para la aparición de cepas epizooticas. Así mismo, se ha considerado también la encefalitis equina del Este (EEE), virus que ha causado epizootia equina en la selva y cuya participación en la patología humana aún no ha sido definida. Los resultados encontrados mediante prueba de neutralización en placa de VEE y EEE en células VERO con sueros humanos muestran una variada prevalencia. Siendo la mas alta para VEE en el departamento de San Martín 57 por ciento y EEE en el departamento de Loreto 62 por ciento y con relación a equinos VEE 68 por ciento y EEE 65 por ciento ambos en el departamento de Loreto.

The Venezuelan Encephalities virus (VEE) complex include 1AB, 1C, 1D, 1E serotypes, but the 1AB and IC serotypes are the only one related to epizooties. In Peru, the epizootic virus appeared in the 30th and the last appearance was in 1973 and the serotype isolated was 1AR. In Loreto in the Peruvian jungle was isolated VEE ID serotype from human febrile illness; however, previous surveillance founded VEE antibodies in the same area. In this study we want to know the prevalence of VEE and Eastern Equine Encephalities virus (EEE) antibodies in humans and equines for the jungle area where the equine population were increasing lately. U sing neutralization test by plaque reduction we founded a variety of prevalence. In the human sera the highest prevalence for VEE was 57% in San Martin and for EEE was 62% in Loreto. In equines sera the highest prevalence for VEE was 68% and for EEE was 65% in Loreto.