Related Experiment Videos
Respiratory syncytial virus genotypes and disease severity among children in hospital
J N Fletcher1, R L Smyth, H M Thomas
1Department of Medical Microbiology and Genito-Urinary Medicine, University of Liverpool.
Objectives:
To determine the spectrum of N and G genotypes of respiratory syncytial virus (RSV) causing respiratory tract infection and whether particular genotypes are associated with severity of infection.
Patients And Methods:
Nasopharyngeal aspirates (NPAs) were obtained from 114 infants with acute respiratory tract infection due to RSV over two seasons. Viral mRNA was extracted from NPAs or cultured virus, reverse transcribed, and the cDNA amplified by the polymerase chain reaction using primers directed to parts of the N and G gene respectively. Amplicons were separately digested with four different restriction endonucleases for each gene. The fragments were separated by agarose gel, electrophoresis, and the electrophoretic patterns used to assign the various genotypes. Disease severity was assessed as very mild (upper respiratory tract signs only), mild (coryza and signs of lower respiratory tract infection), moderate (requiring nasogastric or intravenous fluids), and severe (requiring oxygen or ventilation).
Results:
Five of the six known N genotypes were detected, but NP4 and NP2 were found most frequently. There was no association between N genotype and disease severity. Six G (SHL) genotypes were detected. Significantly (p = 0.04) more of the infants infected with the SHL2 genotype had severe or moderate disease.
Conclusions:
During the seasonal peaks of RSV respiratory tract infection at least 10 different RSV genotypes cocirculated. While there is no association between N genotypes and disease severity, infection with the SHL2 G genotype appears to result in moderate to severe disease.
Insights
Respiratory syncytial virus (RSV) infection involves multiple N and G genotypes. While N genotypes don't impact severity, the SHL2 G genotype is linked to moderate to severe respiratory tract infections in infants.
Area of Science:
- Virology
- Infectious Diseases
- Pediatrics
Background:
- Respiratory syncytial virus (RSV) is a major cause of infant respiratory tract infections.
- Understanding RSV genotype diversity is crucial for disease management and prevention.
- Previous studies suggest potential links between RSV genotypes and disease severity.
Purpose of the Study:
- To identify the range of N and G genotypes of RSV causing respiratory tract infections in infants.
- To investigate if specific RSV genotypes are associated with varying degrees of disease severity.
Main Methods:
- Nasopharyngeal aspirates from 114 infants with RSV infection were analyzed over two seasons.
- Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) were used to genotype RSV N and G genes.
- Disease severity was categorized based on clinical signs and treatment requirements.
Main Results:
- Five N genotypes and six G (SHL) genotypes of RSV were detected.
- No significant association was found between N genotypes and disease severity.
- Infants infected with the SHL2 G genotype showed a higher incidence of moderate to severe disease (p=0.04).
Conclusions:
- At least 10 different RSV genotypes circulated during seasonal peaks.
- RSV N genotypes are not associated with disease severity.
- The SHL2 G genotype of RSV is a potential indicator for moderate to severe respiratory tract infections in infants.