Diarrhea is one of the most common causes of morbidity and mortality in children worldwide. Rotavirus is the most common cause of infectious diarrhea both in developed and developing countries. However, bacterial causes such as Salmonella typhi and Vibrio cholerae still play an important role in developing countries. Newly developed vaccines for rotavirus, S. typhi, and V. choleae are highly immunogenic and safe in children.
Child ; Developing Countries ; Diarrhea ; Humans ; Rotavirus ; Salmonella typhi ; Typhoid-Paratyphoid Vaccines ; Vaccines ; Vibrio cholerae

Typhoid fever, a serious systemic infection caused by Salmonella enterica serovar Typhi, breaks out in developing countries. However, existing vaccines only induce relatively low protective effects with humoral responses and do not stimulate secondary immune response, especially to young people. The objective of this study is to evaluate the immunogenicity of the vaccine containing virulence capsular polysaccharide (Vi) conjugated with the optimal ratios of non-toxic variant of diphtheria toxin (CRM(197)) in mice. Six-week-old BALB/c female mice were injected intraperitoneally three times at intervals of 14 days and sera were collected on days 0, 14, 28, 42 and 56 post-injection. The efficacy of the vaccine was evaluated by comparing between negative control group injected with PBS and vaccine groups injected with Vi or Vi-CRM(197) conjugate of different ratio. Vi and CRM(197)-specific antibody responses were evaluated using enzyme-linked immunosorbent assay. The result showed that Vi-CRM(197)-1 group revealed the highest and significant Vi-specific IgG immune responses among the other groups and Vi group (p < 0.01). In conclusion, Vi-CRM(197)-1 conjugate vaccine induced the highest humoral immune response in mice and may be used as an effective vaccine to replace the existing typhoid vaccine for infants under 2 years old.
Animals ; Antibody Formation ; Child, Preschool ; Developing Countries ; Diphtheria Toxin ; Enzyme-Linked Immunosorbent Assay ; Female ; Humans ; Immunity, Humoral ; Immunoglobulin G ; Infant ; Mice* ; Salmonella enterica* ; Salmonella typhi* ; Salmonella* ; Typhoid Fever ; Typhoid-Paratyphoid Vaccines ; Vaccines ; Virulence

The immunogenicity of a single dose of Salmonella typhi(S.typhi) Vi capsular polysaccharide(CPS) vaccine was evaluated before, and at 1, 3, 12, and 36 months after vaccination. Eighty-five adults(20-28 years of age) and sixty-four children(8-16 years of age) received a single dose of 25 micrograms Vi CPS vaccine intramuscularly, and antibody titers to Vi CPS were measured by passive hemagglutination. Of 149 vaccinees, 138(92.6%) showed seroconversion at 1 month after vaccination, and then 138 out of 141(97.9%) did at 3 months. Of 137 vaccinees, 116(84.7%) maintained a persistent rise in Vi antibody titer 12 months after vaccination, and 55 out of 100(55.0%) had a 4-fold or greater rise at 36 months. No significant adverse reactions were observed. Booster injection may be needed 3-5 years after vaccination.
Adolescent ; Adult ; Antibodies, Bacterial/blood ; Antigens, Bacterial/immunology ; Child ; Evaluation Studies ; Human ; Polysaccharides, Bacterial/*immunology ; Salmonella typhi/*immunology ; Typhoid Fever/prevention & control ; Typhoid-Paratyphoid Vaccines/adverse effects/immunology/*therapeutic use

OBJECTIVETo study the regulating effects of a novel CpG oligodeoxynuleotide and the synergistic effect of chitosan-nanoparticles (CNP) with CpG on immune responses of mice, which were used to develop a novel immunoadjuvant to boost immune response to conventional vaccines.

METHODSA novel CpG ODN containing 11 CpG motifs was synthesized and its bioactivities to stimulate the proliferation of lymphocytes of pig in vitro were detected. Then it was entrapped with CNP prepared in our laboratory by the method of ionic cross linkage, and immunized Kunming mice were co-inoculated with paratyphoid vaccine. The peripheral blood was collected weekly from the tail vein of inoculated mice to detect the contents of IgG, IgA, IgM, and specific antibody against salmonella as well as the levels of interleukin-2 (IL2), IL-4, and IL-6 by SABC-ELISA assay. The numbers of leucocytes, monocytes, granuloytes, and lymphocytes were calculated separately using the routine method. The experimental mice were orally challenged with virulent salmonella 35 days after inoculation.

RESULTSThis CpG ODN could remarkably provoke the proliferation of lymphocytes of pig in vitro in contrast with the control (P < 0.05). Compared with those of the control, immunoglobulins, including IgG, IgA, IgM, and specific antibodies to paratyphoid vaccine, increased significantly in sera from the CpG or CpG-CNP-vaccinated mice (P < 0.05). IL-2, IL-4, and IL-6 increased remarkably in sera from immunized mice (P < 0.05). The leucocytes, monocytes, granuloytes, and lymphocytes of the mice immunized with CpG or CpG-CNP were also increased in number (P < 0.05). After the challenge, these immunity values were elevated in the mice vaccinated with CpG or CpG-CNP. The immunized mice all survived, while the control mice fell ill with evident lesions with diffuse hemorrhage in stomach, small intestine, and peritoneum.

CONCLUSIONSCpG ODN entrapped with CNP is a promising effective immunoadjuvant for vaccination, which promotes humoral and cellular immune responses, enhances immunity and resistance against salmonella by co-administration with paratyphoid vaccine.

Adjuvants, Immunologic ; administration & dosage ; pharmacology ; Animals ; Antibodies, Bacterial ; blood ; Cell Proliferation ; Chitosan ; chemistry ; Drug Therapy, Combination ; Enzyme-Linked Immunosorbent Assay ; Immunoglobulin Isotypes ; blood ; Interleukins ; blood ; Lymphocyte Activation ; drug effects ; Lymphocytes ; cytology ; Mice ; Nanoparticles ; chemistry ; Oligodeoxyribonucleotides ; administration & dosage ; pharmacology ; Paratyphoid Fever ; immunology ; prevention & control ; Salmonella ; physiology ; Salmonella Infections, Animal ; immunology ; prevention & control ; Swine ; immunology ; Typhoid-Paratyphoid Vaccines ; immunology

INTRODUCTIONEnteric fever is a multisystemic infection which largely affects children. This study aimed to analyse the epidemiology, clinical presentation, treatment and outcome of paediatric enteric fever in Singapore.

MATERIALS AND METHODSA retrospective review of children diagnosed with enteric fever in a tertiary paediatric hospital in Singapore was conducted from January 2006 to January 2012. Patients with positive blood cultures for Salmonella typhi or paratyphi were identified from the microbiology laboratory information system. Data was extracted from their case records.

RESULTSOf 50 enteric fever cases, 86% were due to Salmonella typhi, with 16.3% being multidrug resistant (MDR) strains. Sixty-two percent of S. typhi isolates were of decreased ciprofloxacin susceptibility (DCS). Five cases were both MDR and DCS. The remaining 14% were Salmonella paratyphi A. There were only 3 indigenous cases. Ninety-four percent had travelled to typhoid-endemic countries, 70.2% to the Indian subcontinent and the rest to Indonesia and Malaysia. All patients infected with MDR strains had travelled to the Indian subcontinent. Anaemia was a significant finding in children with typhoid, as compared to paratyphoid fever (P = 0.04). Although all children were previously well, 14% suffered severe complications including shock, pericardial effusion and enterocolitis. None had typhoid vaccination prior to their travel to developing countries.

CONCLUSIONEnteric fever is largely an imported disease in Singapore and has contributed to significant morbidity in children. The use of typhoid vaccine, as well as education on food and water hygiene to children travelling to developing countries, needs to be emphasised.

Adolescent ; Anemia ; epidemiology ; Anti-Bacterial Agents ; therapeutic use ; Child ; Child, Preschool ; Drinking Water ; Drug Resistance, Multiple, Bacterial ; physiology ; Enterocolitis ; epidemiology ; Female ; Food Contamination ; Health Education ; Hospitals, Pediatric ; Humans ; India ; Indonesia ; Infant ; Malaysia ; Male ; Paratyphoid Fever ; drug therapy ; epidemiology ; microbiology ; Pericardial Effusion ; epidemiology ; Retrospective Studies ; Salmonella paratyphi A ; physiology ; Salmonella typhi ; physiology ; Shock ; epidemiology ; Singapore ; epidemiology ; Tertiary Care Centers ; Travel ; Typhoid Fever ; drug therapy ; epidemiology ; microbiology ; prevention & control ; Typhoid-Paratyphoid Vaccines ; therapeutic use

This experiment was conducted to assess the efficacy of typhoid vaccine newly produced by purifying Vi antigen of Salmonella typhi. With Karber method, LD50 of challenging organism (S. typhi ty2) was determined as 6.31 CFU/mouse, and then the organism was used for the study. With Probits method, ED50 of the vaccine was determined as 0.016 microgram / 0.5 ml / mouse. The ELISA titer (0.5097+/-0.0606) was 4 times in the group treated with high dose (0.25 microgram/0.5ml) as in control (0.1113+/-0.0110). Six major protein bands of 66, 55, 35, 33, 18, and 9 kd were detected in Western blot analysis with serum of a vaccine treated mouse, whereas only one weak band of about 35 kd was detected with serum of a control mouse. We concluded that typhoid vaccine produced by purifying Vi antigen of S. typhi very effectively prevent S. typhi infection in mice.
Animals ; Antibodies, Bacterial/immunology ; Antigens, Bacterial/*immunology/*isolation&purification ; Blotting, Western ; Enzyme-Linked Immunosorbent Assay ; Lethal Dose 50 ; Logistic Models ; Male ; Mice ; Mice, Inbred BALB C ; Polysaccharides, Bacterial/*immunology/*isolation&purification ; Salmonella typhi/chemistry/*immunology ; Typhoid Fever/immunology/prevention&control ; Typhoid-Paratyphoid Vaccines/administration & dosage/*immunology/*isolation&purification

Avian pathogenic Escherichia coli (APEC) is a causative agent for a number of extra intestinal diseases and account for significant losses to the poultry industry. Since protective immunity against APEC is largely directed to virulence antigens, we have individually expressed four different viulence antigens, papA, papG, IutA, and CS31A, using an attenuated Salmonella Typhimurium and a plasmid pBB244. Following oral immunization of mice with combination of two or four of these strains, serum IgG and mucosal IgA responses were elicited against each antigen represented in the mixture. The antigen-specific mucosal IgA responses were significantly higher in the group of mice immunized with the heat-labile Escherichia coli enterotoxin B subunit (LTB) strain than those in the group of mice immunized without the LTB strain. While, there was no significant difference between these two groups in antigen-specific serum IgG responses. The results showed that LTB could act as mucosal immune adjuvant. To assess the nature of immunity, the distribution of antigen-specific IgG isotypes was analyzed. All groups promoted Th1-type immunity as determined by the IgG2a/IgG1 ratio. Thus, our findings provided evidence that immunization with a combination of several vaccine strains is one of the strategies of developing effective vaccines against APEC.
Animals ; Enterotoxins ; Escherichia coli ; Immunity, Mucosal* ; Immunization ; Immunoglobulin A ; Immunoglobulin G ; Intestinal Diseases ; Mice* ; Plasmids ; Poultry ; Salmonella typhimurium ; Salmonella Vaccines* ; Salmonella* ; Vaccines ; Virulence

BACKGROUND: This study is aimed at evaluating immunogenicity by measuring immunoglobulin A (IgA) seroconversion rate through common mucosal immune system and adverse reactions after vaccination of oral live attenuated Salmonella typhi (S. typhi) Ty21a vaccine in Korean population. METHODS: A commercially available oral live attenuated vaccine of S. typhi strain Ty21a (Zerotyph(r) capsule, Boryung Biopharma Co., Seoul, Korea) was given to volunteers; children above 6 years, adolescents, and adults who have never infected with S. typhi nor received S. typhi vaccination. The vaccines were given in three doses, with two day interval between the doses. Seroconversion was determined by ELISPOT (enzyme-linked immunospot) assay. Adverse reactions after vaccination were evaluated in 12 institutions by direct interviewing with vaccinees. RESULTS: A total of 93 volunteers for evaluation of seroconversion were enrolled. Seroconversion rate in the the below 16 year-old group was 73.8% (31/42) and that of over 16 year-old group was 86.3% (44/51), which was not statistically different. Adverse reaction were found in 8.6% (40/465). Gastrointestinal symptoms were most common (6.5%, 30/465). Adverse reactions were found in 5.2% (24/465) after 1st administration, 4.5% (21/462) after 2nd, and 2.6% (12/461) after 3rd. Frequency of adverse reactions was significantly higher after 1st administration (P<0.05). CONCLUSION: Oral live attenuated S. typhi vaccine, Zerotyph(r) capsule, had good immnuogenicity and safety through intestinal immune system.
Adolescent ; Adult ; Child ; Enzyme-Linked Immunospot Assay ; Humans ; Immune System ; Immunoglobulin A ; Salmonella typhi* ; Salmonella* ; Seoul ; Vaccination ; Vaccines ; Volunteers

BACKGROUND: This study is aimed at evaluating immunogenicity by measuring immunoglobulin A (IgA) seroconversion rate through common mucosal immune system and adverse reactions after vaccination of oral live attenuated Salmonella typhi (S. typhi) Ty21a vaccine in Korean population. METHODS: A commercially available oral live attenuated vaccine of S. typhi strain Ty21a (Zerotyph(r) capsule, Boryung Biopharma Co., Seoul, Korea) was given to volunteers; children above 6 years, adolescents, and adults who have never infected with S. typhi nor received S. typhi vaccination. The vaccines were given in three doses, with two day interval between the doses. Seroconversion was determined by ELISPOT (enzyme-linked immunospot) assay. Adverse reactions after vaccination were evaluated in 12 institutions by direct interviewing with vaccinees. RESULTS: A total of 93 volunteers for evaluation of seroconversion were enrolled. Seroconversion rate in the the below 16 year-old group was 73.8% (31/42) and that of over 16 year-old group was 86.3% (44/51), which was not statistically different. Adverse reaction were found in 8.6% (40/465). Gastrointestinal symptoms were most common (6.5%, 30/465). Adverse reactions were found in 5.2% (24/465) after 1st administration, 4.5% (21/462) after 2nd, and 2.6% (12/461) after 3rd. Frequency of adverse reactions was significantly higher after 1st administration (P<0.05). CONCLUSION: Oral live attenuated S. typhi vaccine, Zerotyph(r) capsule, had good immnuogenicity and safety through intestinal immune system.
Adolescent ; Adult ; Child ; Enzyme-Linked Immunospot Assay ; Humans ; Immune System ; Immunoglobulin A ; Salmonella typhi* ; Salmonella* ; Seoul ; Vaccination ; Vaccines ; Volunteers

OBJECTIVETo develop an anti-caries DNA vaccine-loaded Salmonella typhimurium (St) ghost and enhance the efficacy of immune responses induced by anti-caries DNA vaccine via mucosal route.

METHODSBoth pREP4 and PhiX gene E expression plasmids were transformed into StJ357 and then induced with isopropyl β-D-1-thiogalactopyranoside (IPTG). The bacterial ghosts (BG) were collected after wash and loaded with anti-caries DNA vaccine pGJGLU/VAX. Mice were divided into four groups and immunized through the nasal route with pGJGLU/VAX-loaded BG (Group Ghost+pGJGLU/VAX), pVAX1-loaded BG (Group Ghost+pVAX1), pGJGLU/VAX-Bupivacaine complex (Group pGJGLU/VAX) and pVAX1-Bupivacaine complex (Group pVAX1), respectively. Enzyme-linked immunosorbent assay (ELISA) was used to evaluate the immune responses.

RESULTSELISA results showed that group Ghost+pGJGLU/VAX had significantly higher level of specific anti-GLU SIgA antibody [(0.367 ± 0.086) A/µg] compared with group Ghost+pVAX1 [(0.122 ± 0.077) A/µg], Group pGJGLU/VAX[(0.068 ± 0.068) A/µg] or Group pVAX1[(0.089 ± 0.089) A/µg] (P = 0.028, 0.012 or 0.030, respectively).

CONCLUSIONSSt ghost was developed successfully, which enhanced the efficacy of immune responses induced by anti-caries DNA vaccine pGJGLU/VAX via the nasal route.

Animals ; Antibodies, Antinuclear ; Bacterial Vaccines ; Dental Caries ; prevention & control ; Immunoglobulin A, Secretory ; Mice ; Plasmids ; Salmonella typhimurium ; Vaccines, DNA