Molecular evidence for tick-borne encephalitis virus in ticks in South Korea.

To investigate whether tick-borne encephalitis viruses (TBEVs) are present in South Korea, Korean ixodid ticks were tested for TBEV RNA. Ticks (n = 2460) were collected from wild and domestic animals or by flagging at forest and grassland in 12 regions of five provinces in 2005-06. Four species in two genera were identified, yielding 197 sample pools (1-20 ticks per pool); from these, 12 envelope protein gene fragments of TBEV were amplified by reverse transcriptase-nested polymerase chain reaction (RT-nested PCR). Ten of the 2104 adult ticks (0.4%) and two of the 356 nymph ticks (0.2%) were positive for the envelope (E) gene of TBEV. Twelve TBEV RNA-positive samples were detected in Gyeonggi and Gangwon provinces. Phylogenetic analysis showed that the E genes of the TBEV isolates were clustered with the Western European subtype (98% identity). This study suggests that TBEVs may exist in Korea.

Polymorphisms at codons 129 and 219 of the prion protein gene (PRNP) are not associated with sporadic Alzheimer's disease in the Korean population.

Polymorphisms of prion protein gene (PRNP) at codons 129 and 219 play an important role in the susceptibility to Creutzfeldt-Jakob disease (CJD). Alzheimer's disease (AD) and prion diseases, such as CJD, are both characterized by the accumulation of abnormally folded proteins in the brain. An association between sporadic AD and the PRNP polymorphism at codon 129 has been reported in several studies, but other studies have failed to confirm an association. To investigate whether PRNP polymorphisms are associated with an increased risk for developing sporadic AD in the Korean population, we compared the genotype, allele, and haplotype frequencies of PRNP polymorphisms in 271 sporadic AD patients with those in 236 healthy Koreans. Our study does not show a significant difference in PRNP genotype, allele, and haplotype frequency at codons 129 and 219 between sporadic AD and normal controls. Analyses stratifying by age at disease onset, and gender also failed to reveal any association between these polymorphisms and sporadic AD. These results indicate that these PRNP polymorphisms have no direct influence on the susceptibility to sporadic AD in the Korean population.