# Development and Validation of a New Set of Primers for Identification of Circulating Lineages and Palivizumab/Nirsevimab Resistance in HRSV Isolates from Cabo Verde

## TL;DR

Researchers developed new primers to identify HRSV lineages and check for resistance to treatments in Cabo Verde, finding common global lineages without resistance mutations.

## Contribution

A new primer set was developed and validated for HRSV lineage identification and resistance detection in Cabo Verde.

## Key findings

- HRSV lineages A.D.2.2.1, A.D.3, B.D.4.1.1, and B.D.E.1 were identified in Cabo Verde.
- No mutations conferring resistance to Palivizumab or Nirsevimab were detected in HRSV isolates.
- Continuous monitoring of HRSV genotypes is recommended to detect potential resistance mutations.

## Abstract

In Cabo Verde, Acute Respiratory Infection caused by various pathogens was the most reported condition in children under 5 years old between 2014–2020, and the fourth leading cause of mortality in this age group, with Human Respiratory Syncytial Virus (HRSV) being one of the main etiological agents. However, limited literature on the subject hinders the study of its epidemiology and the evaluation of potential implications for public health. In this work, we developed and validated a primer collection for the amplification and sequencing of the G and F genes of HRSV, using a sequential workflow including conventional and semi-nested PCR, followed by Sanger sequencing. This strategy not only allowed for the identification of HRSV linages but also facilitated the detection of mutants in the HRSV F protein, a critical step towards evaluating and ensuring the continued efficacy of Nirsevimab or Palivizumab as prophylactic therapies. Our analysis revealed the presence of the HRSV lineages A.D.2.2.1, A.D.3, B.D.4.1.1, and B.D.E.1, corresponding to the globally circulating lineages during the study period (years 2019 and 2022). No previously described mutations in the F protein that confer resistance to Palivizumab and Nirsevimab were found. However, continuous monitoring of HRSV genotypes is crucial to promptly identifying resistant viruses, considering their potential impact on public health.