RESUMO
BACKGROUND: Studies of the immunogenicity of the killed bivalent whole cell oral cholera vaccine, Shanchol, have been performed in historically cholera-endemic areas of Asia. There is a need to assess the immunogenicity of the vaccine in Haiti and other populations without historical exposure to Vibrio cholerae. METHODOLOGY/PRINCIPAL FINDINGS: We measured immune responses after administration of Shanchol, in 25 adults, 51 older children (6-17 years), and 47 younger children (1-5 years) in Haiti, where cholera was introduced in 2010. A≥4-fold increase in vibriocidal antibody titer against V. cholerae O1 Ogawa was observed in 91% of adults, 74% of older children, and 73% of younger children after two doses of Shanchol; similar responses were observed against the Inaba serotype. A≥2-fold increase in serum O-antigen specific polysaccharide IgA antibody levels against V. cholerae O1 Ogawa was observed in 59% of adults, 45% of older children, and 61% of younger children; similar responses were observed against the Inaba serotype. We compared immune responses in Haitian individuals with age- and blood group-matched individuals from Bangladesh, a historically cholera-endemic area. The geometric mean vibriocidal titers after the first dose of vaccine were lower in Haitian than in Bangladeshi vaccinees. However, the mean vibriocidal titers did not differ between the two groups after the second dose of the vaccine. CONCLUSIONS/SIGNIFICANCE: A killed bivalent whole cell oral cholera vaccine, Shanchol, is highly immunogenic in Haitian adults and children. A two-dose regimen may be important in Haiti, and other populations lacking previous repeated exposures to V. cholerae.
Assuntos
Vacinas contra Cólera/imunologia , Cólera/prevenção & controle , Vibrio cholerae O139/imunologia , Vibrio cholerae O1/imunologia , Adolescente , Adulto , Anticorpos Antibacterianos/sangue , Carga Bacteriana/efeitos dos fármacos , Criança , Pré-Escolar , Cólera/epidemiologia , Cólera/imunologia , Vacinas contra Cólera/administração & dosagem , Epidemias , Feminino , Haiti , Humanos , Lactente , Masculino , Vacinas de Produtos Inativados/administração & dosagem , Vacinas de Produtos Inativados/imunologia , Adulto JovemRESUMO
No commercially live vaccine against cholera caused by Vibrio cholerae O139 serogroup is available and it is currently needed. Virulent O139 strain CRC266 was genetically modified by firstly deleting multiple copies of the filamentous phage CTXφ, further tagging by insertion of the endoglucanase A coding gene from Clostridium thermocellum into the hemagglutinin/protease gene and finally deleting the mshA gene, just to improve the vaccine biosafety. One of the derived strains designated as TLP01 showed full attenuation and good colonizing capacity in the infant mouse cholera model, as well as highly immunogenic properties in the adult rabbit and rat models. Since TLP01 lacks MSHA fimbriae, it is refractory to infection with another filamentous phage VGJφ and therefore protected of acquiring CTXφ from a recombinant hybrid VGJφ/CTXφ. This strategy could reduce the possibilities of stable reversion to virulence out of the human gut. Furthermore, this vaccine strain was impaired to produce biofilms under certain culture conditions, which might have implications for the strain survival in natural settings contributing to vaccine biosafety as well. The above results has encouraged us to consider TLP01 as a live attenuated vaccine strain having an adequate performance in animal models, in terms of attenuation and immunogenicity, so that it fulfills the requirements to be evaluated in human volunteers.
Assuntos
Vacinas contra Cólera/imunologia , Proteínas de Fímbrias/imunologia , Vibrio cholerae O139/imunologia , Administração Oral , Animais , Anticorpos Antibacterianos/imunologia , Derrame de Bactérias , Sequência de Bases , Biofilmes , Cólera/imunologia , Cólera/prevenção & controle , Vacinas contra Cólera/genética , Vacinas contra Cólera/farmacologia , Modelos Animais de Doenças , Fezes/microbiologia , Proteínas de Fímbrias/genética , Mucosa Intestinal/imunologia , Lectina de Ligação a Manose/genética , Lectina de Ligação a Manose/imunologia , Dados de Sequência Molecular , Coelhos , Ratos , Ratos Sprague-Dawley , Alinhamento de Sequência , Deleção de Sequência/genética , Estatísticas não Paramétricas , Vacinas Atenuadas/genética , Vacinas Atenuadas/imunologia , Vacinas Atenuadas/farmacologia , Vibrio cholerae O139/genéticaRESUMO
Vibrio cholerae O139 Bengal emerged as a second aetiologic agent of cholera in South Asia in late 1992. This new serogroup arose from a Vibrio cholerae O1 strain by deletion of the chromosomal region encoding O1 specificity and acquisition of a novel 35-kb region encoding the O139 specificity. Previous studies indicated significant phenotypic and genotypic changes in O139 isolates over the years since its first appearance. This prompted us to study possible polymorphism in the 35-kb novel region encoding the O139 specificity. A total of 17 V. cholerae O139 isolates originating from different countries and years in South Asia and China, and a single unrelated V. cholerae O139 isolate from Argentina were studied. The 35-kb chromosomal region was amplified as two fragments of 12 and 23 kb in an extended PCR from all isolates. These amplicons were then treated separately with seven different restriction enzymes and separated by agarose gel electrophoresis. The South Asian and Chinese isolates gave identical patterns for the same enzymes, but different patterns for different enzymes, thus exhibiting no polymorphism in the 35-kb region. However, the Argentine isolate gave distinct patterns for most of the enzymes confirming its different origin. This data indicated that the portion of the chromosome encoding the O139 antigen specificity is highly conserved. As found in previous studies, the early O139 isolates were resistant to trimethoprim-sulfamethoxazole (TMP-SMX) and vibriostatic compound, O/129, and CAMP- haemolysin positive. The isolates of later years diverged exhibiting different patterns by pulsed-field gel electrophoresis (PFGE), and becoming susceptible to TMP-SMX and O/129, and CAMP-haemolysin negative.
Assuntos
DNA Bacteriano/genética , Antígenos O/genética , Polimorfismo Genético , Vibrio cholerae O139/genética , Antibacterianos/farmacologia , Argentina , Ásia , China , Cólera/microbiologia , Eletroforese em Gel de Campo Pulsado , Hemólise , Humanos , Antígenos O/química , Antígenos O/metabolismo , Pteridinas/farmacologia , Combinação Trimetoprima e Sulfametoxazol/farmacologia , Vibrio cholerae O139/classificação , Vibrio cholerae O139/imunologia , Vibrio cholerae O139/isolamento & purificaçãoRESUMO
The hemagglutinin/protease (HA/P) seems to be an attractive locus for the insertion of heterologous tags in live cholera vaccine strains. A deltaCTXphi spontaneous mutant derived from a pathogenic strain of O139 Vibrio cholerae was sequentially manipulated to obtain hapA Colon, two colons celA derivatives which were later improved in their environmental safety by means of a thyA mutation. All the strains here obtained showed similar phenotypes in traits known to be remarkable for live cholera vaccines irrespective of their motility phenotypes, although the hapA mutants had a 10-fold decrease in their colonisation capacity compared with their parental strains in the infant mouse cholera model. However, the subsequent thyA mutation did not affect their colonisation properties in the same model. These preliminary results pave the way for further clinical assays to confirm the possibilities of these vaccine prototypes as safe and effective tools for the prevention of O139 cholera.