E1 Tor Vibrio cholerae (EVC) strains may be classifled into two kinds-epidemigenic (EEVC) strains and non-epidemigenic (NEEVC) strains-based on a phage-biotyping system. A large number of EEVC strains have been screen...E1 Tor Vibrio cholerae (EVC) strains may be classifled into two kinds-epidemigenic (EEVC) strains and non-epidemigenic (NEEVC) strains-based on a phage-biotyping system. A large number of EEVC strains have been screened for toxigenic and putative colonization attributes. One such naturally occurring strain (designated IEM 101) has been found which is devoid of genes encoding cholera toxin (CT), accessory cholera enterotoxin (ACE), zonula occludens toxin (ZOT), but possesses RS1 sequences and toxin-coregulated pilus A gene (tcpA) although tcpA is poorly expressed. It expresses type B pili but does not posses type C pili. It is an E1 Tor Ogawa strain and does not cause fluid accumulation in rabbit ileal loop tests. Active immunization of rabbits with strain IEM 101 elicited good protection against challenge with virulent strains of V cholerae O1. Oral administrationcaused no side effects in 15 human volunteers, colonized the gut for four to ten days and elicited good immune responses展开更多
Background The adenovirus-based HIV-1 vaccine developed by Merck Company suffered from an unexpected failure in September 2007. This generated a big shift in the strategy of HIV vaccine development with renewed focus ...Background The adenovirus-based HIV-1 vaccine developed by Merck Company suffered from an unexpected failure in September 2007. This generated a big shift in the strategy of HIV vaccine development with renewed focus on the induction of neutralizing antibodies. A major challenge in developing an HIV-1 vaccine is to identify immunogens and adopt delivery methods that can elicit broadly neutralizing antibodies against primary isolates of different genetic subtypes. Methods Most circulating HIV-1 isolates in China are composed of clades Thai-B, CRF_BC and CRF01_AE. In order to construct DNA vaccines against these 3 HIV-1 subtypes, DNA vaccines carrying the gp120 regions from HIV-1 isolates of GX48（AE）, GX79（AE）, NX22（BC）, GS22（BC）, HN24（Thai-B） were constructed. Expression of gp120 from these DNA vaccines was detected by Western blotting in transiently transfected 293T cells. Pilot immunizations of New Zealand white rabbits were performed using the strategy of ＂DNA prime plus protein boost＂ and the neutralizing antibody response was detected in a Tzm-bl cell based assay against different HIV-1 strains. Results Response of gp120-specific antibody was relatively low after DNA primes （mean titer=10^4.72）; however, the titer of gp120-specific antibody went up with 2 protein boosts （mean titer=10^6.81）. Above all, neutralizing antibody （Nab） titers induced by this combined approach were much better than those elicited by DNA or protein used alone （P 〈0.01）. Neutralizing activities of immunized rabbit sera against several pseudoviruses and laboratorial strains were evaluated, most rabbit sera primed with monovalent vaccine were capable of neutralizing only 1 of 5 viruses, however, sera primed with the polyvalent DNA vaccines were able to neutralize at least 2 of 5 viruses. Conclusion Polyvalent DNA prime plus protein boost is an effective immunization strategy to broaden the neutralization breadth and further research should be performed on the basis of this pilot study.展开更多
文摘E1 Tor Vibrio cholerae (EVC) strains may be classifled into two kinds-epidemigenic (EEVC) strains and non-epidemigenic (NEEVC) strains-based on a phage-biotyping system. A large number of EEVC strains have been screened for toxigenic and putative colonization attributes. One such naturally occurring strain (designated IEM 101) has been found which is devoid of genes encoding cholera toxin (CT), accessory cholera enterotoxin (ACE), zonula occludens toxin (ZOT), but possesses RS1 sequences and toxin-coregulated pilus A gene (tcpA) although tcpA is poorly expressed. It expresses type B pili but does not posses type C pili. It is an E1 Tor Ogawa strain and does not cause fluid accumulation in rabbit ileal loop tests. Active immunization of rabbits with strain IEM 101 elicited good protection against challenge with virulent strains of V cholerae O1. Oral administrationcaused no side effects in 15 human volunteers, colonized the gut for four to ten days and elicited good immune responses
基金This work was supported by the grants from the China 973 Project （No. 2006CB504206） and the Natural Science Foundation of China （No. 30700706）. In addition, this work was supported by a funding from Jiangsu Provincial Key Infectious Diseases Laboratory.
文摘Background The adenovirus-based HIV-1 vaccine developed by Merck Company suffered from an unexpected failure in September 2007. This generated a big shift in the strategy of HIV vaccine development with renewed focus on the induction of neutralizing antibodies. A major challenge in developing an HIV-1 vaccine is to identify immunogens and adopt delivery methods that can elicit broadly neutralizing antibodies against primary isolates of different genetic subtypes. Methods Most circulating HIV-1 isolates in China are composed of clades Thai-B, CRF_BC and CRF01_AE. In order to construct DNA vaccines against these 3 HIV-1 subtypes, DNA vaccines carrying the gp120 regions from HIV-1 isolates of GX48（AE）, GX79（AE）, NX22（BC）, GS22（BC）, HN24（Thai-B） were constructed. Expression of gp120 from these DNA vaccines was detected by Western blotting in transiently transfected 293T cells. Pilot immunizations of New Zealand white rabbits were performed using the strategy of ＂DNA prime plus protein boost＂ and the neutralizing antibody response was detected in a Tzm-bl cell based assay against different HIV-1 strains. Results Response of gp120-specific antibody was relatively low after DNA primes （mean titer=10^4.72）; however, the titer of gp120-specific antibody went up with 2 protein boosts （mean titer=10^6.81）. Above all, neutralizing antibody （Nab） titers induced by this combined approach were much better than those elicited by DNA or protein used alone （P 〈0.01）. Neutralizing activities of immunized rabbit sera against several pseudoviruses and laboratorial strains were evaluated, most rabbit sera primed with monovalent vaccine were capable of neutralizing only 1 of 5 viruses, however, sera primed with the polyvalent DNA vaccines were able to neutralize at least 2 of 5 viruses. Conclusion Polyvalent DNA prime plus protein boost is an effective immunization strategy to broaden the neutralization breadth and further research should be performed on the basis of this pilot study.
