The Vi conjugate typhoid vaccine is safe, elicits protective levels of IgG anti-Vi, and is compatible with routine infant vaccines.

Abstract

Typhoid fever remains a serious problem in developing countries. Current vaccines are licensed for individuals who are 5 years old or older. A conjugate of the capsular polysaccharide (CP) of Salmonella enterica serovar Typhi (Vi) bound to recombinant exoprotein A of Pseudomonas aeruginosa (Vi-rEPA) enhanced Vi immunogenicity and protected 2- to 5-year-olds in Vietnam. In this study, Vi-rEPA was evaluated for use in infants. A total of 301 full-term Vietnamese infants received Expanded Program on Immunization (EPI) vaccines alone or with Vi-rEPA or Haemophilus influenzae type b-tetanus toxoid conjugate (Hib-TT) at 2, 4, and 6 months and Vi-rEPA or Hib-TT alone at 12 months. Infants were visited 6, 24, and 48 h after each injection to monitor adverse reactions. Maternal, cord, and infant sera were assayed for IgG anti-Vi and for IgG antibodies to Hib CP and the diphtheria, tetanus, and pertussis toxins at 7, 12, and 13 months. No vaccine-related serious adverse reactions occurred. In the Vi-rEPA group, the IgG anti-Vi geometric mean (GM) increased from the cord level of 0.66 to 17.4 enzyme-linked immunosorbent assay units (EU) at 7 months, declined to 4.76 EU at 12 months, and increased to 50.1 EU 1 month after the 4th dose (95% of infants had levels of ≥ 3.5 EU, the estimated protective level). Controls had no increase of the IgG anti-Vi GM. Infants with cord anti-Vi levels of <3.5 EU responded with significantly higher IgG anti-Vi levels than those with levels of ≥ 3.5 EU. Anti-diphtheria, -tetanus, and -pertussis toxin levels were similar in all groups. Vi-rEPA was safe, induced protective anti-Vi levels, and was compatible with EPI vaccines, and it can be used in infants. High cord IgG anti-Vi levels partially suppressed infant responses to Vi-rEPA.

• Authors: Vu Dinh Thiem, Feng-Ying C Lin, Do Gia Canh, Nguyen Hong Son, Dang Duc Anh, Nguyen Duc Mao, Chiayung Chu, Steven W Hunt, John B Robbins, Rachel Schneerson, Shousun C Szu
• Journal: Clinical and vaccine immunology : CVI (Clin Vaccine Immunol) Vol. 18 Issue 5 Pg. 730-5 (May 2011) ISSN: 1556-679X [Electronic] United States
• PMID: 21411598 (Publication Type: Journal Article, Research Support, N.I.H., Intramural)

Chemical References

• Antibodies, Bacterial
• Bacterial Proteins
• Haemophilus Vaccines
• Haemophilus influenza type b polysaccharide vaccine-tetanus toxin conjugate
• Immunoglobulin G
• Polysaccharides, Bacterial
• Recombinant Proteins
• Tetanus Toxoid
• Typhoid-Paratyphoid Vaccines
• Vaccines, Conjugate
• Vi polysaccharide vaccine, typhoid

Topics

• Adolescent
• Adult
• Antibodies, Bacterial (blood)
• Bacterial Proteins (genetics, immunology)
• Female
• Haemophilus Vaccines (administration & dosage, adverse effects, immunology)
• Humans
• Immunoglobulin G (blood)
• Infant
• Infant, Newborn
• Male
• Polysaccharides, Bacterial (administration & dosage, adverse effects, immunology)
• Pseudomonas aeruginosa (genetics, immunology)
• Recombinant Proteins (genetics, immunology)
• Tetanus Toxoid (administration & dosage, adverse effects, immunology)
• Typhoid-Paratyphoid Vaccines (administration & dosage, adverse effects, immunology)
• Vaccines, Conjugate (administration & dosage, adverse effects, immunology)
• Vietnam
• Young Adult