title: Novel hepatitis B virus genotype a subtyping assay that distinguishes subtype Aa from Ae and its application in epidemiological studies.
abstract: The eight genotypes of hepatitis B virus (HBV) have different geographical distributions, virological characteristics, and clinical manifestations. A unique subtype of HBV genotype A (HBV/A) was reported in sub-Saharan Africa, raising the possibility that patients infected with this subtype (HBV/Aa ["a" for African and Asian]) may have different clinical outcomes than other HBV/A isolates (HBV/Ae ["e" for European]). Comparison between 30 HBV/Aa and 30 HBV/Ae isolates indicated that almost all HBV/Ae isolates had G at nucleotide (nt) 1809 and C at nt 1812, whereas HBV/Aa isolates had T1809/T1812. Taking advantage of these two single nucleotide polymorphisms (SNPs), a novel subtype-specific PCR assay in the X/precore/core region was developed. This assay was combined with a restriction fragment length polymorphism assay using BglII in a different region (nt 1984 to 1989), which has a SNP distinguishing HBV/Aa from HBV/Ae, resulting in 100% specificity for the combined assay. Application of the subtyping assay using sera from 109 paid donors in the United States indicated significantly different distributions of HBV/A subtypes among races; African-Americans, Caucasians, and Hispanics had HBV/Ae, whereas Asians had mainly HBV/Aa, suggesting that the HBV/Aa isolates may have been imported by recent immigration from Asia. In conclusion, the specificity and sensitivity of the combined subtyping assay were confirmed, and its usefulness was demonstrated in a practical context.
authors.affiliation: Department of Clinical Molecular Informative Medicine, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan.
authors.forename: Izumi
authors.initials: I
authors.lastname: Hasegawa
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Anna
authors.initials: A
authors.lastname: Kramvis
authors.forename: Takanobu
authors.initials: T
authors.lastname: Kato
authors.forename: Fuminaka
authors.initials: F
authors.lastname: Sugauchi
authors.forename: Subrat K
authors.initials: SK
authors.lastname: Acharya
authors.forename: Etsuro
authors.initials: E
authors.lastname: Orito
authors.forename: Ryuzo
authors.initials: R
authors.lastname: Ueda
authors.forename: Michael C
authors.initials: MC
authors.lastname: Kew
authors.forename: Masashi
authors.initials: M
authors.lastname: Mizokami
mesh_terms: D000293:Adolescent; D000328:Adult; D001483:Base Sequence; D001782:Blood Donors; D005260:Female; D005838:Genotype; D006509:Hepatitis B / Q000453:epidemiology* / Q000821:virology; D006515:Hepatitis B virus / Q000145:classification* / Q000235:genetics*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods*; D012150:Polymorphism, Restriction Fragment Length; D020641:Polymorphism, Single Nucleotide; D015995:Prevalence; D044469:Racial Groups; D012680:Sensitivity and Specificity; D014773:Virology / Q000379:methods