Genomic Insights Into Respiratory Syncytial Virus Circulation Patterns and Neutralization by Anti-F Monoclonal Antibodies in Panama (2018-2024).

BACKGROUND

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infections and hospitalization in infants and children. Whole genome sequencing (WGS) plays a critical role in understanding the evolution and epidemiology of RSV. Limited studies have been conducted in Central America and the Caribbean, and none have specifically focused on lineages involved in recent outbreaks. Furthermore, no assays currently exist to evaluate the sensitivity of the RSV fusion protein to monoclonal antibodies.

METHODS

In Panama, an epidemiological surveillance system tracks RSV activity through the collection of nasopharyngeal samples from patients with acute respiratory infections. Between January 2018 and July 2024, 303 RSV-positive samples were analyzed by RT-qPCR. RSV-B was the dominant subgroup in 2018, but following years had alternating dominance between RSV-A and RSV-B. Of the 303 samples, 115 underwent WGS. Additionally, neutralization assays were done using different Anti-F Monoclonal Antibodies.

RESULTS

In RSV-A, 11 lineages were identified, with 3 to 5 cocirculating during each annual outbreak, and a shift in predominance from A.D.1 (2019) to A.D.5.2 (2023-2024). In RSV-B, two lineages circulated: B.D.4.1.1 (2018-2020) and its descendant B.D.E.1, which predominated from 2021 onward. Several monoclonal antibodies, including nirsevimab's precursor MEDI8897*, effectively neutralized the RSV strains in neutralization assays.

CONCLUSIONS

Although Panama has not yet implemented a preventive therapy for RSV, this step could modify outbreak dynamics. The findings from this study provide a baseline reference prior to the implementation of preventive therapies against RSV in Panama and the region, facilitating the assessment of potential changes in the evolutionary dynamics of the virus.