Safety and Immunogenicity of Vi Conjugate Vaccines for Typhoid Fever in Adults, Teenagers, and 2- to 4-Year-Old Children in Vietnam

Kossaczká, Zuzana; Lin, Feng-Ying C.; Hó, Vô Anh; Thủy, Nguyễn Thị Thanh; Bay, Phan Van Be; Thanh, Tran Cong; Khiem, Ha Ba; Trach, Dang Duc; Karpas, Arthur B.; Hunt, Steven; Bryla, Dolores A.; Schneerson, Rachel; Robbins, John B.; Szu, Shousun C.

doi:10.1128/iai.67.11.5806-5810.1999

Cited by 126 publications

(59 citation statements)

References 34 publications

(36 reference statements)

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“…However Vi-negative variants of S. Typhi and S. Paratyphi A are emerging as a cause of typhoidal disease. These strains lack Vi antigen which is considered to be the main virulence factor and is the major target for vaccine development [23]. Other pathogenicity mechanisms must therefore play a role in infection and if uncontrolled as a result of poor immune protection these strains may emerge as competitors to Vi-positive S. Typhi.…”

Section: Discussionmentioning

confidence: 99%

Multiplex PCR for differential diagnosis of emerging typhoidal pathogens directly from blood samples

Ali

Haque

et al. 2008

Epidemiol. Infect.

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Classically Salmonella enterica serovar Typhi (S. Typhi) is associated with typhoid, a major health problem in developing countries. However, in recent years S. Paratyphi A and Vi-negative variants of S. Typhi have emerged rapidly. We have developed a nested multiplex PCR targeting five different genes for differential diagnosis of typhoidal pathogens which has been optimized to be directly applicable on clinical blood samples. Of 42 multiplex PCR-positive blood samples, 26, nine, and two were Vi-positive S. Typhi, Vi-negative S. Typhi and S. Paratyphi A, respectively, and five patients were found to have mixed infection. Seventeen patients grew Salmonella from blood culture and the remaining 25 were positive in the Salmonella-specific PCR. Tests with several common pathogens confirmed the specificity of the assay. We conclude that the proposed multiplex PCR is rapid, sensitive and specific for the diagnosis of typhoidal pathogens directly from blood samples.

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Section: Discussionmentioning

confidence: 99%

Multiplex PCR for differential diagnosis of emerging typhoidal pathogens directly from blood samples

Ali

Haque

et al. 2008

Epidemiol. Infect.

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“…Anti-rabies Ab titres were calculated at the Central Veterinary Laboratories, Surrey, UK using the fluorescent antibody virus neutralization method, as described by Cliquet et al (1998). Anti-Vi IgG Kossaczka et al (1999). Full details of all laboratory procedures can be found elsewhere (Moore et al 2004).…”

Section: Pakistanmentioning

confidence: 99%

Effect of month of vaccine administration on antibody responses in The Gambia and Pakistan

Moore

Collinson

Fulford

et al. 2006

Tropical Med Int Health

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Summaryobjective To explore the relationship between calendar month of administration and antibody (Ab) response to vaccination in subjects from The Gambia and Pakistan, two countries with distinct patterns of seasonality.methods Three cohorts were investigated: Responses to rabies and pneumococcal vaccine were assessed in 472 children (mean age 8 years, males 53%) from rural Gambia. Responses to tetanus, diphtheria and hepatitis B (HBsAg) were investigated in 138 infants also from The Gambia (birth to 52 weeks of age, males 54%). Responses to rabies and Vi typhoid vaccines were assessed in 257 adults from Lahore, Pakistan (mean age 29.4 years, males 57%).results In Gambian children, significant associations were observed between month of vaccination and Ab response for the pneumococcal and rabies vaccines. As no consistent pattern by month was observed between the responses, it is assumed that different immunomodulatory stimuli or mechanisms were involved. In Pakistani adults, a significant pattern by month of vaccination was observed with both rabies and typhoid vaccine. No monthly influences were observed in the infant study to the tetanus, diphtheria or the HbsAg vaccines.conclusions Antibody responses to certain specific vaccines are influenced by month of administration. Further research is required to elucidate the precise mechanisms explaining these observations, but a co-stimulatory effect of seasonally variable environmental antigens is a likely cause. Future studies of Ab response to vaccination in countries with a seasonally dependent environment should consider month of vaccination when interpreting study findings.

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“…However, in clinical studies in healthy adults, neither Typhax nor Vi conjugates elicited a significant increase in anti-Vi IgG antibody titers 1to 4-weeks following a second administration [16,22]. However, increases in anti-Vi responses were observed in 2-4 year old children with the Vi-rEPA conjugate vaccine following a second dose 6 weeks after the initial immunization [15] and with Typbar-TCV 720 days following the initial dose [12]. Together these data suggest that Vi conjugates can elicit a memory response although the timing of the second dose and age of the patient may be factors.…”

Section: Discussionmentioning

confidence: 93%

“…The National Institutes of Health developed a vaccine candidate consisting of Vi PS conjugated to a recombinant Pseudomonas aeruginosa exoprotein A (Vi-rEPA). This vaccine was well tolerated and elicited protective levels of anti-Vi antibody titers in adults, children, and infants [15][16][17][18] having completed Phase 2 evaluation. Novartis Vaccine Institute for Global Health (NVGH) demonstrated that Vi PS conjugated to CRM197, a genetic toxoid of diphtheria toxin [19,20], was safe and immunogenic in Phase 1 and 2 trials [21].…”

Section: Introductionmentioning

confidence: 99%

A phase 1 randomized safety, reactogenicity, and immunogenicity study of Typhax: A novel protein capsular matrix vaccine candidate for the prevention of typhoid fever

Cartee¹,

Thanawastien²,

Griffin³

et al. 2020

PLoS Negl Trop Dis

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Background Typhoid fever remains a significant cause of morbidity and mortality in developing countries especially in children �5 years old. Although the widely available unconjugated Vi polysaccharide vaccines are efficacious, they confer limited, short-term protection and are not approved for young children or infants. Vi conjugate vaccines, however, are now licensed in several typhoid endemic countries for use in children >6 months of age. As an alternative to conjugate vaccines, Matrivax has applied its novel 'virtual conjugation' Protein Capsular Matrix Vaccine (PCMV) technology to manufacture Typhax, which is composed of Vi polysaccharide entrapped in a cross-linked CRM197 matrix. Methodology A randomized, double-blinded, dose escalating Phase 1 study was performed to compare the safety and immunogenicity of three dose levels of aluminum phosphate adjuvanted Typhax (0.5, 2.5, or 10 μg of Vi antigen) to the FDA licensed vaccine, Typhim Vi, and placebo. Groups of 15 healthy adult subjects aged 18 to 55 years were randomized and received Typhax, Typhim Vi, or placebo at a ratio of 9:3:3. Typhax and placebo were administered in a two-dose regimen (Days 0 and 28) while Typhim Vi was administered as a single-dose on Day 0 with a placebo administered on Day 28. All doses were administered as a 0.5 mL intramuscular (IM) injection in a blinded fashion. The anti-Vi IgG antibody response was determined preimmunization (Day 0) and on Days 14, 28, 42, and 180 by ELISA. Seroconversion was defined as a titer 4-fold or greater above baseline. Principal findings All Typhax vaccine regimens were well tolerated and adverse events were low in number and primarily characterized as mild in intensity and similar in incidence across the treatment

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Safety and Immunogenicity of Vi Conjugate Vaccines for Typhoid Fever in Adults, Teenagers, and 2- to 4-Year-Old Children in Vietnam

Cited by 126 publications

References 34 publications

Multiplex PCR for differential diagnosis of emerging typhoidal pathogens directly from blood samples

Multiplex PCR for differential diagnosis of emerging typhoidal pathogens directly from blood samples

Effect of month of vaccine administration on antibody responses in The Gambia and Pakistan

A phase 1 randomized safety, reactogenicity, and immunogenicity study of Typhax: A novel protein capsular matrix vaccine candidate for the prevention of typhoid fever

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