Molecular analysis of the bacille Calmette-Guérin vaccine strain currently being used in Iran

BACKGROUND

In developing countries, tuberculosis (TB) infection control remains a challenge. The bacille Calmette-Guérin (BCG) vaccine is the only effective vaccine available for TB control. Iran uses a local BCG vaccine strain with an unknown substrain.

OBJECTIVE

To investigate the molecular characteristics of the current BCG strain being used in Iran using comparative genomics of the evolutionarily late strains, including BCG vaccines Pasteur, BCG-Danish, BCG-Glaxo, BCG-Prague, BCG-Frappier, BCG-Connaught and BCG-Moreau.

METHODS

A total of 67 different vials of BCG vaccine were cultured. DNA was extracted using the modified cetrimonium bromide (CTAB) method, and multiplex polymerase chain reaction (PCR) was performed to determine four target genomic regions of difference (RD) 1, RD8, RD16 and SenX3-RegX3, and to see whether RD2 and RD14 were present.

RESULTS

Our results showed that all studied batches were Mycobacterium bovis; molecular analysis revealed that the Iranian vaccine strains possess RD8, RD16 and SenX3-RegX3 regions but not RD1, RD2 and RD14. All of the vaccine batches analysed were compatible with BCG-Pasteur 1173p2, the original strain.

CONCLUSION

All of the BCG strains studied were recognised as the BCG-Pasteur 1173p2 strain. No genetic diversity among stocks and ready-for-use vaccine vials were detected.

Measles vaccination coverage and seroprevalence of anti-measles antibody in south-east Islamic Republic of Iran

Discrepancies often exist between recorded immunization coverage and the real immunity level in a community. To estimate the vaccination coverage against measles in south-east Islamic Republic of Iran, a crosssectional study was conducted in 3 districts during summer 2011. Using probability proportional to size cluster sampling, 1368 children aged 30-54 months were selected. Serum samples of 663 who had received 2 injections of mumpsmeasles- rubella (MMR) vaccine were checked for anti-measles IgG. Vaccination coverage for the second dose of MMR vaccine was 93.7%. The prevalence of anti-measles IgG in those who had received at least 2 MMR vaccine doses was 94.6%. There was a statistically significant association between the serological results and variables that reflected poor accessibility to health services. Combining serological results with coverage data, the proportion of the community protected against measles was estimated as 88.6%, which was below the limits defined for the measles elimination goals.

Seroprevalence of poliovirus antibodies among 7-month-old infants after 4 doses of oral polio vaccine in Sistan-va-Baluchestan, Islamic Republic of Iran

Despite high coverage rates of polio vaccine in the Islamic Republic of Iran, the seroconversion rates of infants may be inadequate. This study measured seroprevalence of antibodies against poliovirus serotypes 1 to 3 (PV1, PV2 and PV3) in 7-month-old infants who had received at least 4 doses of trivalent oral polio vaccine. A serosurvey was conducted in 2010 in rural areas of Chabahar, Sistan-va-Baluchestan province. Using cluster sampling, 72 eligible infants were tested for antibody against the 3 poliovirus serotypes according to WHO guidelines. Antibody titres ≥ 1:10 were considered positive. The seropositive rates for antibody against PV1, PV2 and PV3 were 84.7%, 95.8% and 70.8% respectively. Only 63.9% of participants were seropositive for antibodies against all 3 poliovirus serotypes. Except for PV2, the seroprevalence of antibody against the other 2 poliovirus serotypes, especially PV3, was unsatisfactory.

Risk of polio reintroduction to border regions of Islamic Republic of Iran: seroprevalence study of children with at least 5 doses of oral polio vaccine

Movements of populations from countries where polio has not been eradicated is a concern in the Islamic Republic of Iran. A cross-sectional, community-based study was implemented in 2010 in 2 districts in Sistan-va-Baluchestan Province near the south-east border. The aim was to determine the seroprevalence of antibodies in children aged 20 (± 2) months who had received at least 5 doses of trivalent oral polio vaccine. Using cluster sampling, 365 children were enrolled for serological testing. Antibody titres ≥ 1:10 were considered positive. Seropositive rates for antibody against poliovirus serotypes 1, 2 and 3 were 94.1%, 96.7% and 78.3% respectively. The lowest seropositive rate was for antibody against polio serotype 3 (PV3) among boys (58.3%). Exclusive breastfeeding showed a direct relationship with antibody response to PV3 (OR = 2.0; 95% CI: 1.1-3.6). Improving community protection against PV3 is an urgent programme priority.

InvasiveVibrio cholerae01 E1 Tor Inaba in a 3-day-old neonate: case report

A 3-day-old girl with invasive V. cholerae infection is described. Her mother had cholera in the perinatal period. Because of retracted nipples, she expressed milk and fed her infant by bottle. The infant died on the 2nd day of admission.