title: Reduced neutralizing antibody titer against genotype I virus in swine immunized with a live-attenuated genotype III Japanese encephalitis virus vaccine.
abstract: A shift in prevalence from Japanese encephalitis virus (JEV) genotype III (GIII) to GI virus has been observed in several Asian countries. Genotype I virus was first detected in Taiwan in 2008, and became the dominant JEV island-wide within a year. We conducted a serosurvey using swine serum specimens from multiple counties in Taiwan following the transmission season in 2009 and results showed 67-100% of JEV seropositive swine showed evidence of GI virus infection. The envelope (E) protein is a structural protein that elicits protective neutralizing antibodies (Nt Ab). The GIII at222 (a live-attenuated swine vaccine) 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 in 2009). Twenty piglets were vaccinated with two doses of at222 vaccine, and serum specimens were collected to evaluate the strain-specific Nt Ab titer against GIII at222, GIII CJN, and GI TC2009-1 viruses. Seropositivity rates (Nt Ab titer≥1:10) and geometric mean titers (GMT) were similar against at222 and CJN viruses. However, sera from swine vaccinated with at222 were least potently neutralizing against GI TC2009-1 virus. The estimated protective threshold against GI virus was observed only when the PRNT50 against at222 virus was ≥1:320. Thus, our current study indicates that the live-attenuated at222 swine vaccine can be partially protective against GI virus, and suggests that the efficacy of GIII swine vaccines currently used may require a comprehensive reevaluation in the field.
authors: Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 40227, Taiwan.
authors: Yi-Chin
authors: YC
authors: Fan
authors: Jo-Mei
authors: JM
authors: Chen
authors: Yi-Ying
authors: YY
authors: Chen
authors: Jen-Wei
authors: JW
authors: Lin
authors: Shyan-Song
authors: SS
authors: Chiou
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology*; D000914:Antibodies, Viral / Q000097:blood; D056738:Cross Protection / Q000276:immunology; D004664:Encephalitis Virus, Japanese / Q000737:chemistry / Q000235:genetics* / Q000276:immunology*; D004672:Encephalitis, Japanese / Q000517:prevention & control / Q000662:veterinary*; D005838:Genotype; D022321:Japanese Encephalitis Vaccines / Q000276:immunology*; D013552:Swine; D013553:Swine Diseases / Q000276:immunology* / Q000517:prevention & control / Q000821:virology*; D013624:Taiwan; D014611:Vaccination / Q000662:veterinary; D014613:Vaccines, Attenuated / Q000276:immunology; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D022321:Japanese Encephalitis Vaccines; D014613:Vaccines, Attenuated; D014759:Viral Envelope Proteins