Researchers identify a new type of respiratory syncytial virus associated with long-term infection

new Journal of Infectious Diseases The study examines the host pathogen or genetic risk factors for RSV infection and whether certain viral variants are associated with prolonged infection.

Study: Virological genetic determinants of prolonged respiratory syncytial virus infection among infants in a healthy birth cohort.  Image credit: ART_ur / Shutterstock.com

Stady: Viral genetic determinants of prolonged respiratory syncytial virus infection among infants in a healthy birth cohort. Image credit: ART_ur / Shutterstock.com

RSV transmission

Human lung bone virus, more commonly known as respiratory syncytial virus (RSV), can lead to significant mortality and morbidity worldwide.

All children between the ages of two and three years have been infected with RSV at least once. RSV mainly infects the epithelium of the lower and upper respiratory tract; However, it has also been found in sources other than the airway. Although RSV usually causes acute respiratory infections, it can also lead to persistent or prolonged illness in some individuals.

Prolonged shedding of RSV virus in infants after the first infection has been observed to increase the average duration of shedding virus. However, it is not known whether specific viral agents lead to prolonged infection in infants.

Understanding the characteristics of prolonged infection is essential, as it can increase transmission rates and cause developmental changes in the airway epithelium of young patients. The RSV reservoir is also poorly understood, as it is believed that some strains of RSV remain circulating at low levels in the community, while others may remain seasonal.

about studying

The current study involved healthy infants who had prolonged RSV infection. A viral genome-wide association study (GWAS) using RSV whole genome sequencing was performed to understand the relationship between prolonged RSV infection in infants and viral genotypes.

A human GWAS was performed to analyze the effect of first-year RSV infection risk on genotype. In addition, the local immune response to RSV was evaluated, along with analysis of all viral sequence data.

Finally, a summary of all functional data for the selected variant is provided.

Results

A total of 19 infants met criteria for prolonged infection, which was defined as acute respiratory infection with two or more nasal RSV polymerase chain reaction (PCR) samples with more than 15 days between test dates.

The mean RSV Ct value for the first infection was 25.9, while for the second it was 31.6. The average number of days between infection was 29 days.

RSV infection had little or no effect on the infants’ genotypes. Moreover, prolonged infections were caused by viruses from different strain combinations compared to a single specific strain. Similar RSV sequences were observed for initial and subsequent detection of the virus, suggesting that this was a long-term infection.

A genetic association was observed between prolonged infection and the lead variant, with no other variants associated with the lead variant. The p.E123K/D and p.P218T/S/L variant genotypes were primarily associated with prolonged infection; However, information about the effects of the two variants on regional or local RSV G protein structure was insufficient. In addition, the effect on glycosylation was nonspecific.

conclusions

The current study identified RSV variants that resulted in healthy long-term infants. However, no information was obtained on the genetic susceptibility of the host to RSV infection.

Understanding the viral and host mechanisms that lead to long-term infection can be useful in determining strategies that can control the short- and long-term effects of RSV infection. In addition, identification of RSV variants that cause prolonged infection can help improve vaccine design.

More research is needed to determine the reservoir for RSV, as well as its potential for prolonged infection in immunocompetent hosts.

determinants

The current study was not designed to examine the duration of infection and required additional sampling. In addition to the small cohort size, the researchers were only able to analyze the host’s genetic risk for infection rather than prolonged infection. Finally, the modulating effects of maternal antibody levels on infants have not been measured.

Journal reference:

  • Lawless D, McKennan CJ, Das SR, et al. (2022). Viral genetic determinants of prolonged respiratory syncytial virus infection among infants in a healthy birth cohort. Journal of Infectious Diseases. doi: 10.1093/infdis/jiac442.

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