Rotavirus A is a double-stranded RNA virus in the family Reoviridae that causes the majority of acute rotaviral gastroenteritis in infants and young children worldwide. It is the most prevalent of the rotavirus species and is responsible for most human infections.
Explanation
Rotavirus A virions are non-enveloped and have a triple-layered icosahedral capsid about 70 nm in diameter. The genome consists of eleven double-stranded RNA segments totaling about 18,555 base pairs and encoding six structural (VP1–VP4, VP6, VP7) and six non-structural proteins. Group A viruses are classified by the outer capsid proteins VP7 (G types) and VP4 (P types); at least 36 G and 51 P genotypes have been described, though only a few combinations commonly infect humans. Rotavirus A infects mature enterocytes in the small intestine. The virus enters cells via receptor-mediated endocytosis, replicates within cytoplasmic viroplasms and assembles new virions that are released by cell lysis. The triple-layered capsid protects the genome from gastric acid, allowing the virus to survive transit through the stomach and remain stable in the environment.
Epidemiology and Disease
Rotavirus A is the leading cause of severe diarrhoea among infants and young children, causing about 600,000 deaths annually before the introduction of vaccines. Infection is highly contagious and spreads via the faecal–oral route through contaminated hands, surfaces and water. Group A viruses account for about 95 % of human rotavirus infections. Symptoms include vomiting, watery diarrhoea and fever, which can lead to dehydration. Immunity develops after repeated exposures; however, reinfections with different genotypes occur. Vaccines based on attenuated rotavirus A strains have reduced the disease burden significantly. Control measures include vaccination, improved sanitation and oral rehydration therapy.
Rotavirus A remains a major pathogen despite vaccine availability. Understanding its structure, genome segmentation and transmission helps guide prevention strategies and reduces its impact on child health worldwide.
Related Terms: Rotavirus B, Rotavirus C, Rotavirus H, Norovirus GI, Reoviridae