Hepatitis A: Viral Structure, Classification, Life Cycle, Clinical Symptoms, Diagnosis Error, and Vaccination

Table 2

HAV genotypes and subtypes and their geographical distributions.

Hepatitis A virus genotypes	Hepatitis A virus subtypes	Geographical distribution	Comments	References
Genotype I	A, B, C	Subgenotype IA was reported in China, Japan, Turkey, Russia, Hungary, the United States of America (US), and Germany	(i) Infecting humans, the most frequent genotype is the I genotype. The IA subgenotype is more frequent than IB	[22, 24, 38, 40–42]
			(ii) Genotype IA was most common among strains tested in US outbreak investigations and surveillance during 1996–2015
		Subgenotype IB has been reported in Turkey, the Netherlands, Hungary, France, Italy, Bulgaria, and Egypt	(iii) Genotype IB gained prominence during 2016–2019 person-to-person multistate outbreaks
			(iv) Subgenotype IB is the most prevalent genotype in Turkey
			(v) The cell culture-adapted viruses most commonly used are variants of the Australian strain HM175 (genotype IB) and the German strain GBM (genotype IA)
Genotype II	A, B	Until today, only a few cases of genotype II have been reported	Infect humans	[22, 24, 29, 38, 40, 43, 44]
		With potential African origin of IIA strains and occasionally found in France
Genotype III	A, B	Genotype III has a worldwide distribution pattern. Subgenotype IIIB is mainly seen in Japan	Infect humans	[22, 24, 29, 38, 40, 41, 43, 44]
		Subgenotype IIIA has been reported in Iran, The Netherlands, South Korea, Japan, Afghanistan, Turkey, and India