Infections Caused by HRSV A ON1 Are Predominant among Hospitalized Infants with Bronchiolitis in São Paulo City

Area of Science:

• Virology
• Pediatrics
• Epidemiology

Background:

• Human respiratory syncytial virus (HRSV) is a primary cause of severe respiratory infections in infants globally.
• Multiple HRSV genotypes exist, necessitating ongoing surveillance to understand their prevalence and impact.

Purpose of the Study:

• To identify and characterize the predominant HRSV genotypes responsible for infant bronchiolitis in São Paulo, Brazil, from 2013 to 2015.
• To analyze the clinical and epidemiological features associated with different HRSV genotypes.

Main Methods:

• Studied 94 infants (0-6 months) diagnosed with bronchiolitis.
• Collected clinical and epidemiological data.
• Utilized real-time PCR, conventional PCR, sequencing, and phylogenetic analysis to detect and genotype 16 respiratory viruses from nasopharyngeal secretions.

Main Results:

• A high respiratory virus detection rate (98.9%) was observed, with HRSV accounting for 77.6% of cases.
• The HRSV genotype ON1 (a subtype of HRSVA) was predominant (76.7% of HRSV cases), followed by HRSVB genotypes BA9 and BA10.
• No significant clinical or epidemiological differences were found between infants infected with HRSVA ON1 and those infected with other HRSV genotypes.

Conclusions:

• This study highlights the significant burden of HRSV in infant bronchiolitis in São Paulo.
• The predominance of the HRSVA ON1 genotype, newly identified in this region, underscores the importance of continuous molecular surveillance for emerging viral strains.
• Clinical presentation of bronchiolitis in infants did not significantly vary based on the infecting HRSV genotype in this cohort.