The type-2 variant of human cytomegalovirus glycoprotein N (gN-2) is not the rarest in the Chinese population of Taiwan: Influence of primer design

Studies of the human cytomegalovirus (HCMV) glycoprotein N (gpUL73-gN) showed that genotypic variations exist in different geographic areas, with gN-2 unidentified in Chinese population. The purpose of this study was to determine the HCMV gN variants in the Chinese population of Taiwan. Primers were designed and a polymerase chain reaction (PCR) was carried out on the UL73 gene. The PCR products were subjected to restriction fragment length polymorphism (RFLP) analysis. The same PCR-RFLP assay was repeated using primers published previously to demonstrate the influence of primer design. Of the 48 clinical HCMV isolates, 33 were positive for PCR products by both primer sets. Fifteen were positive only by the “in-house” PCR. The distribution of gN-1, gN-2, gN-3, and gN-4 by RFLP analysis was 14:11:7:17, with one isolate positive for both gN-1 and gN-2. The published primers detected the four genotypes with the number of 14:0:2:17. The under-representation of gN-2 and gN-3 by the method published previously may be due to inappropriate primer design when re-examining the sequences. On the basis of the results of this study, gN-2 is not the rarest gN genotype in the Chinese population of Taiwan. The design of primers used for PCR-RFLP genotyping may have a great influence on the frequency distribution of HCMV genomic variants.