Distinguishing hepatitis B virus (HBV) genotype D from non-D by a simple PCR.

Different HBV genotypes have characteristic geographical distribution, which is important epidemiologically. HBV strains have been classified into eight different genotypes (A-H) on the basis of >8% differences in the entire genomic sequence. Genotypes A and D are predominant in Europe, Africa, and the USA, genotypes B and C are restricted to East Asia, genotype E is found in Africa, and genotype F is found in indigenous populations in Central and South America. Genotype D is prevalent in the Turkish population. HBV genotype D shows a 33-bp deletion in the pre-S1 region that accounts for their smaller genomic size (3182 bp). This deletion can be used to facilitate the identification of genotype D. A primer in the pre-S1 region was designed to discriminate genotype D from non-D by PCR. Sixty genotype D (40 acute and 20 chronic) and 4 genotype A sera identified by restriction fragment length polymorphism (RFLP) were included in the study. Using this simple PCR method, all genotype D sera were identified correctly and the test was able to detect HBV DNA at 1000 genomes per ml. An advantage of this method is that it can differentiate in a mixture of genotypes (genotype D from non-D) provided that one isn't present below 1 x 10(4) copies/ml. In conclusion this method is rapid (approximately 5h) and it will contribute to the epidemiological study of HBV in high prevalence areas of genotype D. It can also differentiate between genotype D from non-D in cases of co-infection.