Tonto, P. B. | bioRxiv Science

bioRxiv2025

Pre-existing YFV-17D immunity mediates T cell cross-protection against DENV-2 infection

Widespread yellow fever virus (YFV) immunity in Sub-Saharan Africa may mitigate orthoflavivirus outbreaks. Here, we investigate whether pre-existing YFV-17D immunity confers cross-protection against dengue virus serotype 2 (DENV-2) in a murine model. IFNAR1-/- mice immunized with YFV-17D exhibited significantly reduced DENV-2 viremia, weight loss, and disease severity, with improved survival compared to YFV-naive controls. Mechanistic studies revealed that cross-protection was mediated by heterologous T cell responses rather than cross-neutralizing antibodies. Depletion of T cells in YFV-17D-immune mice prior to DENV-2 challenge resulted in increased viremia, weight loss, and disease severity, underscoring the protective role of YFV-17D-elicited T cell immunity. Furthermore, YFV-17D-specific T cells displayed cytotoxicity against DENV NS3- and NS5-pulsed cells, demonstrating their functional role in viral control. These findings highlight the critical contribution of heterologous T cell immunity in YFV-17D-mediated protection against DENV-2 and suggest that vaccines designed to elicit T cell responses could enhance cross-protection against orthoflavivirus infections.

immunology↗

bioRxiv2024

Development of RT-RPA-based point-of-care tests for epidemic arthritogenic alphaviruses

Chikungunya (CHIKV), onyong-nyong (ONNV), and Mayaro (MAYV) viruses are transmitted by mosquitoes and known to cause a debilitating arthritogenic syndrome. These alphaviruses have emerged and re-emerged, leading to outbreaks in tropical and subtropical regions of Asia, South America, and Africa. Despite their prevalence, there persists a critical gap in the availability of sensitive and virus-specific point-of-care (POC) diagnostics. Traditional immunoglobulin-based tests such as enzyme-linked immunosorbent assay (ELISAs) often yield cross-reactive results due to the close genetic relationship between these viruses. Molecular diagnostics such as quantitative polymerase chain reaction (qPCR) offer high sensitivity but are limited by the need for specialized laboratory equipment. Recombinase polymerase amplification (RPA), an isothermal amplification method, is a promising alternative to qPCR, providing rapid results with minimal equipment requirements. Here, we report the development and validation of three virus-specific RPA-based POC tests for CHIKV, ONNV, and MAYV. These tests demonstrated both speed and sensitivity, capable of detecting 10 viral copies within 20 minutes of amplification, without exhibiting cross-reactivity. Furthermore, we evaluated the clinical potential of these tests using serum and tissue samples from CHIKV, ONNV, and MAYV-infected mice, as well as CHIKV-infected human patients. We demonstrate that the RPA amplicons derived from the patient samples can be sequenced, enabling cost-effective molecular epidemiological studies. Our findings highlight the significance of these rapid and specific POC diagnostics in improving the early detection and management of these arboviral infections.

microbiology↗