Intra- and intergenotypic variations among human cytomegalovirus gB genotypes.
OBJECTIVE
To study genotypic variations among human cytomegalovirus (HCMV) gB genotypes in clinical samples of Thai patients.


METHODS
gB genotyping of 31 HCMV-DNA-positive clinical samples were determined by PCR-RFLP, gene cloning and DNA sequencing methods.


RESULTS
Eight gB1, 7 gB2, 7 gB3, 6 gB untype (UT1 and UT2) and 3 mixed gB genotypes were first identified by PCR-RFLP. All 3 mixed gB genotype samples and 1 gB2 sample were cloned and confirmed gB genotype by PCR-RFLP. Altogether, 57 strains (27 unique types and 30 transformants) were further analyzed by DNA sequencing method. Discordant results between PCR-RFLP and DNA sequencing methods were demonstrated in 5 samples and 1 clone. The gB UT1 and UT2 were all classified as gB1 except 1 sample of UT1 (9D), suggesting a new variant. Each genotype had a similarity of more than 97%, whereas strains of different genotypes had 77.71-92.75% homology. The most divergent type was gB3.


CONCLUSIONS
Intra- and intergenotypic variations among strains were demonstrated either in individual or distinct patients. Intragenotypic variation in a person occurs possibly due mainly to a point mutation mechanism rather than reinfection of a new gB genotype.
Chantaraarphonkun
S
S
Inter-Department of Medical Microbiology, Graduate School, Chulalongkorn University, Bangkok, Thailand.
Bhattarakosol
P
P
D001483:Base Sequence; D003587:Cytomegalovirus / Q000145:classification* / Q000235:genetics*; D003586:Cytomegalovirus Infections / Q000821:virology*; D016172:DNA Fingerprinting; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D014644:Genetic Variation; D016679:Genome, Viral; D005838:Genotype; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D013785:Thailand
D004279:DNA, Viral