Coxsackievirus B3 is a member of the coxsackievirus B group within Enterovirus B of the Picornaviridae family. It is a non enveloped, icosahedral virus about 30 nm across that contains a single‑stranded positive sense RNA genome. CVB3 infects humans via fecal–oral and respiratory routes and replicates in the mucosa of the gastrointestinal and respiratory tract before disseminating to other organs. Among the coxsackie B serotypes, CVB3 is best known as a leading cause of viral myocarditis.
Structure, entry and pathogenesis
The genome of Coxsackievirus B3 encodes a polyprotein that is cleaved into capsid proteins VP1‑VP4 and non‑structural proteins required for replication and protease activity. The virus uses the coxsackievirus–adenovirus receptor (CAR) on host cells to gain entry. Replication occurs entirely in the cytoplasm using an RNA‑dependent RNA polymerase. CVB3 is acid‑resistant and can survive passage through the stomach, allowing it to infect via the oral route. After primary replication in the oropharynx and intestine, viremia spreads the virus to the heart, pancreas, liver and central nervous system. In cardiomyocytes, CVB3 replication leads to direct cell lysis and triggers innate and adaptive immune responses that can result in acute and chronic myocarditis. Experimental studies show that the virus can hijack host autophagic pathways to enhance replication. CVB3 circulates worldwide and infection peaks in summer and early autumn. There is no approved vaccine or specific antiviral therapy; treatment is supportive.
Clinical significance and examples
Coxsackievirus B3 infection may produce mild nonspecific symptoms such as fever, sore throat or abdominal pain, but it can also cause severe disease. CVB3 is considered the most common enteroviral cause of acute myocarditis and dilated cardiomyopathy, particularly in adolescents and young adults. Patients may present with chest pain, dyspnea, arrhythmias or signs of heart failure, and some cases progress to sudden cardiac death. CVB3 can also cause epidemic pleurodynia, characterised by severe pleuritic chest pain, as well as aseptic meningitis and neonatal sepsis. During outbreaks, cases often cluster in summer months and occur following exposure to contaminated water or close contact with infected individuals. Preventive measures such as proper hand hygiene, safe food handling and disinfection of communal surfaces reduce transmission. Coxsackievirus B3 is a small RNA virus that remains an important cause of viral myocarditis and pleurodynia. Early recognition of cardiac involvement and supportive management are essential to improve outcomes. Related Terms: Myocarditis, Coxsackievirus B4, Coxsackievirus B2, Enterovirus B, Dilated cardiomyopathy