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標題: Reduced neutralizing antibody titer against genotype I virus in swineimmunized with a live-attenuated genotype III Japanese encephalitisvirus vaccine
關鍵字: Japanese encephalitis;Genotype replacement;Protective threshold;Live-attenuated vaccine
Project: Veterinary Microbiology, Volume 163, Issues 3-4, Page(s) 248-256.
A shift in prevalence from Japanese encephalitis virus (JEV) genotype III (GIII) to GI virushas been observed in several Asian countries. Genotype I virus was first detected in Taiwanin 2008, and became the dominant JEV island-wide within a year. We conducted aserosurvey using swine serum specimens from multiple counties in Taiwan following thetransmission season in 2009 and results showed 67–100% of JEV seropositive swineshowed evidence of GI virus infection. The envelope (E) protein is a structural protein thatelicits protective neutralizing antibodies (Nt Ab). The GIII at222 (a live-attenuated swinevaccine) virus E protein differs at eight amino acid residues (E-123, E-129, E-138, E-176, E-209, E-222, E-327 and E-366) from that of the GI TC2009-1 strain (isolated in Taiwan in2009). Twenty piglets were vaccinated with two doses of at222 vaccine, and serumspecimens were collected to evaluate the strain-specific Nt Ab titer against GIII at222, GIIICJN, and GI TC2009-1 viruses. Seropositivity rates (Nt Ab titer 1:10) and geometric meantiters (GMT) were similar against at222 and CJN viruses. However, sera from swinevaccinated with at222 were least potently neutralizing against GI TC2009-1 virus. Theestimated protective threshold against GI virus was observed only when the PRNT50against at222 virus was 1:320. Thus, our current study indicates that the live-attenuatedat222 swine vaccine can be partially protective against GI virus, and suggests that theefficacy of GIII swine vaccines currently used may require a comprehensive reevaluation inthe field.
DOI: 10.1016/j.vetmic.2013.01.017
Appears in Collections:微生物暨公共衛生學研究所

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