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Genotype I (GI) virus has replaced genotype III (GIII) virus as the dominant Japanese encephalitis virus (JEV) in the epidemic area of Asia. The mechanism underlying the genotype replacement remains unclear. Therefore, we focused our current study on investigating the roles of mosquito vector and amplifying host(s) in JEV genotype replacement by comparing the replication ability of GI and GIII viruses. GI and GIII viruses had similar infection rates and replicated to similar viral titers after blood meal feedings in Culex tritaeniorhynchus. However, GI virus yielded a higher viral titer in amplifying host-derived cells, especially at an elevated temperature, and produced an earlier and higher viremia in experimentally inoculated pigs, ducklings, and young chickens. Subsequently we identified the amplification advantage of viral genetic determinants from GI viruses by utilizing chimeric and recombinant JEVs (rJEVs). Compared to the recombinant GIII virus (rGIII virus), we observed that both the recombinant GI virus and the chimeric rJEVs encoding GI virus-derived NS1-3 genes supported higher replication ability in amplifying hosts. The replication advantage of the chimeric rJEVs was lost after introduction of a single substitution from a GIII viral mutation (NS2B-L99V, NS3-S78A, or NS3-D177E). In addition, the gain-of-function assay further elucidated that rGIII virus encoding GI virus NS2B-V99L/NS3-A78S/E177E substitutions re-gained the enhanced replication ability. Thus, we conclude that the replication advantage of GI virus in pigs and poultry is the result of three critical NS2B/NS3 substitutions. This may lead to more efficient transmission of GI virus than GIII virus in the amplifying host-mosquito cycle. [ABSTRACT FROM AUTHOR]

Background: Genotype I (GI) Japanese encephalitis virus (JEV) that replaced GIII virus has become the dominant circulating virus in Asia. Currently, all registered live and inactivated JEV vaccines are derived from genotype III viruses. In Taiwan, the compulsory JEV vaccination policy recommends that children receives four doses of formalin-inactivated Nakayama (GIII) JEV vaccine. Methodology/Principal Findings: To evaluate the influence of genotype replacement on the post-vaccination viral neutralizing ability by GIII and GI viruses, the small panel of vaccinated-children serum specimens was assembled, and the reciprocal 50% plaque-reduction neutralizing antibody titers (PRNT50) were measured against Nakayama vaccine strain, CJN GIII human brain isolate and TC2009-1 GI mosquito isolate. The seropositivity rate (PRNT50≥1∶10) and geometric mean titers (GMT) against the TC2009-1 virus were the lowest among the three viruses. The protective threshold against the CJN and TC2009-1 viruses could only be achieved when the GMT against Nakayama virus was ≥1∶20 or ≥1∶80, respectively. Using undiluted vaccinees' sera, the enhancement of JEV infection in K562 cells was observed in some low or non-neutralizing serum specimens. Conclusions/Significance: Our preliminary study has shown that neutralizing antibodies, elicited by the mouse brain-derived and formalin-inactivated JEV Nakayama vaccine among a limited number of vaccinees, have reduced neutralizing capacity against circulating GI virus, but more detailed studies are needed to address the potential impact on the future vaccine policy. Author Summary: Genotype I (GI) Japanese encephalitis virus (JEV) that replaced GIII virus has become the dominant circulating virus in Asia; however, all available JEV vaccines are derived from genotype III viruses, and no study has been conducted on the cross-neutralization and protection elicited by GIII JEV vaccines against GI viruses using vaccinated children's serum specimens collected from the general population. Genotype I virus was first detected in Taiwan in 2008, and became the dominant circulating JEV, and was island-wide within a year. In the present study, the small panel of GIII virus vaccinated-children serum specimens were not only showed lower strain-specific neutralization against GI virus as compared to the GIII vaccine and human isolates but also observed the enhancement of GI virus infection in K562 cells in some low or non-neutralizing serum specimens. These preliminary results indicated the reduced neutralization potency due to genotype replacement should be closely monitored in the JE epidemic/endemic regions in the future. [ABSTRACT FROM AUTHOR]

Background: Genotype I (GI) Japanese encephalitis virus (JEV) that replaced GIII virus has become the dominant circulating virus in Asia. Currently, all registered live and inactivated JEV vaccines are derived from genotype III viruses. In Taiwan, the compulsory JEV vaccination policy recommends that children receives four doses of formalin-inactivated Nakayama (GIII) JEV vaccine. Methodology/Principal Findings: To evaluate the influence of genotype replacement on the post-vaccination viral neutralizing ability by GIII and GI viruses, the small panel of vaccinated-children serum specimens was assembled, and the reciprocal 50% plaque-reduction neutralizing antibody titers (PRNT50) were measured against Nakayama vaccine strain, CJN GIII human brain isolate and TC2009-1 GI mosquito isolate. The seropositivity rate (PRNT50≥1:10) and geometric mean titers (GMT) against the TC2009-1 virus were the lowest among the three viruses. The protective threshold against the CJN and TC2009-1 viruses could only be achieved when the GMT against Nakayama virus was ≥1:20 or ≥1:80, respectively. Using undiluted vaccinees' sera, the enhancement of JEV infection in K562 cells was observed in some low or non-neutralizing serum specimens. Conclusions/Significance: Our preliminary study has shown that neutralizing antibodies, elicited by the mouse brain-derived and formalin-inactivated JEV Nakayama vaccine among a limited number of vaccinees, have reduced neutralizing capacity against circulating GI virus, but more detailed studies are needed to address the potential impact on the future vaccine policy. [ABSTRACT FROM AUTHOR]

Background: Although the previous study demonstrated the envelope protein of dengue viruses is under purifying selection pressure, little is known about the genetic differences of full-length viral genomes of DENV-3. In our study, complete genomic sequencing of DENV-3 strains collected from different geographical locations and isolation years were determined and the sequence diversity as well as selection pressure sites in the DENV genome other than within the E gene were also analyzed., Results: Using maximum likelihood and Bayesian approaches, our phylogenetic analysis revealed that the Taiwan's indigenous DENV-3 isolated from 1994 and 1998 dengue/DHF epidemics and one 1999 sporadic case were of the three different genotypes - I, II, and III, each associated with DENV-3 circulating in Indonesia, Thailand and Sri Lanka, respectively. Sequence diversity and selection pressure of different genomic regions among DENV-3 different genotypes was further examined to understand the global DENV-3 evolution. The highest nucleotide sequence diversity among the fully sequenced DENV-3 strains was found in the nonstructural protein 2A (mean +/- SD: 5.84 +/- 0.54) and envelope protein gene regions (mean +/- SD: 5.04 +/- 0.32). Further analysis found that positive selection pressure of DENV-3 may occur in the non-structural protein 1 gene region and the positive selection site was detected at position 178 of the NS1 gene., Conclusion: Our study confirmed that the envelope protein is under purifying selection pressure although it presented higher sequence diversity. The detection of positive selection pressure in the non-structural protein along genotype II indicated that DENV-3 originated from Southeast Asia needs to monitor the emergence of DENV strains with epidemic potential for better epidemic prevention and vaccine development.

Introduction: The purpose of this study was to assess the severity of malocclusion in young Asian men in relation to types of malocclusion and orthodontic treatment need., Methods: Study models of 339 male army recruits (age, 17-22 years) with no history of orthodontic treatment were assessed. The peer assessment rating (PAR) index was used to determine the severity of their malocclusions. Logistic regression and receiver operating characteristics (ROC) curves were performed to evaluate the PAR index in relation to treatment need assessed by the dental health component (DHC) and the esthetic component (EC) of the index of orthodontic treatment need., Results: The mean PAR scores were 17, 20, 28, and 18 for Class I, Class II Division 1, Class II Division 2, and Class III, respectively. PAR scores were highly correlated with DHC and EC scores (P < .001). An increase of 1 point in the PAR score significantly increased the likelihood of orthodontic treatment need for dental-health reasons or esthetic impairment (by 1.17 times [95% CI 1.13-1.21] or 1.25 times [95% CI 1.19-1.31]). The areas under the ROC curves for PAR index were 84% and 94% for the DHC and EC assessments, respectively, suggesting that PAR scores were better predicators of esthetic than dental health impairment for assessing Asian malocclusions. The optimum cutoff points were PAR scores of 17 and 20 for dental health and esthetic impairment, respectively., Conclusions: Class II malocclusions were more severe than Class I or III in Asian men. Malocclusions with definite treatment need had PAR scores that were significantly greater than those with borderline, little, or no need. ROC curves showed that the PAR index had an acceptable level of validity with the professional assessment of orthodontic treatment need in Asian malocclusions. The optimum cutoff PAR scores were 17 and 20 in relation to DHC and EC assessment, respectively. The PAR index was more predictive of esthetic than dental health need.