Respiratory Syncytial Virus (RSV) continues to represent a serious threat to global health, particularly among infants and immunocompromised individuals. Historically, research efforts have focused on RSV-A, supported by the well-established Memphis 37 challenge strain. Yet, the equally critical RSV-B serotype lacked a reliable, controlled human challenge model—until now. hVIVO has delivered a significant milestone with the creation of the RSV-B London strain, meticulously developed under cGMP conditions to ensure safety, consistency, and scientific rigour.
This breakthrough stemmed from a careful selection process that began in 2022, with bronchoalveolar lavage samples collected from RSV-positive infants. These clinical samples underwent a stringent triage process, ensuring only the highest quality viruses moved forward. The final candidate demonstrated robust viability, ability to propagate in GMP Wi-38 cells, genetic suitability, and a complete absence of adventitious agents. This methodical approach safeguarded the integrity of the final challenge stock, setting a new benchmark for viral challenge studies.
The production process was equally exacting. Through a series of controlled passages in GMP-certified environments, the RSV-B London strain was amplified and purified. The final product underwent a comprehensive suite of quality control tests, including sterility, viral genome sequencing, adventitious agent screening, and functional assays in human airway epithelium models. Each step confirmed the virus’s stability, safety, and infectivity, establishing a solid foundation for its use in human studies.
Early clinical data from the characterisation study are highly encouraging. To date, eight healthy volunteers have been successfully inoculated with the RSV-B London strain. The infection model has exhibited an outstanding safety profile with no serious adverse events reported. Participants experienced expected RSV symptoms that mirrored those observed with the established RSV-A Memphis 37 strain, confirming the reliability and predictability of the model. No unforeseen medical concerns have arisen, and the infection course has been both manageable and well-tolerated.
The RSV-B London strain is notably contemporaneous with currently circulating RSV-B viruses and was produced using human cells, eliminating concerns of non-human host adaptation. This biological fidelity enhances the relevance and applicability of challenge study results, making it an indispensable tool for accelerating the development of next-generation RSV vaccines and antiviral therapies.
With the creation of this RSV-B challenge agent, hVIVO has not only expanded its leadership in controlled human infection models but has also bridged a critical gap in respiratory virus research. This strategic advancement offers pharmaceutical partners a faster, more controlled pathway to validate candidate products, reducing the time and cost associated with traditional field trials where RSV serotype prevalence can vary unpredictably.
hVIVO’s pioneering work with the RSV-B London strain sets the stage for a new chapter in vaccine and therapeutic innovation. As demand for respiratory disease solutions intensifies, hVIVO stands out as a catalyst for progress, offering unmatched expertise, state-of-the-art facilities, and a growing portfolio of high-value challenge agents.
hVIVO plc (formerly Open Orphan plc) is a rapidly growing specialist contract research organisation (CRO) and the world leader in testing infectious and respiratory disease vaccines and antivirals using human challenge clinical trials, providing end-to-end early clinical development services for its broad and long-standing client base of biopharma companies.
