RESUMO
Universal vaccination of children for hepatitis A virus (HAV) has emerged as a cost-effective strategy to prevent this infection in regions with high incidence of symptomatic disease. Age-specific seroprevalence surveys are practical and reliable methods to estimate the rate of susceptibility in populations, and to help the implementation of vaccination policies. We surveyed the age-specific HAV seroprevalence in a nationally representative sample of Iranian adolescent students aged 10-18 years. Serum samples (n = 2494) were tested by enzyme immunoassay for total anti-HAV antibody. The overall rate of HAV seropositivity was 64% [95% confidence interval (CI), 62-66), which increased sharply from 14·8% (95% CI 7-23) at age 10 years to 72·9% (95% CI 68-78) at age 13 years, without a significant increase up to age 18 years. No significant difference in HAV seroprevalence was observed between males and females (63% vs. 65·1%), or urban and rural areas (63·4% vs. 65·2%); the seropositivity rate was similar in four different socioeconomic regions of Iran. We conclude that the seroconversion rate of HAV is high in Iranian adolescents and therefore mass vaccination of children may be necessary and should be considered by national health authorities.
Assuntos
Vacinas contra Hepatite A/administração & dosagem , Hepatite A/epidemiologia , Adolescente , Criança , Análise por Conglomerados , Feminino , Geografia , Hepatite A/prevenção & controle , Hepatite A/virologia , Humanos , Incidência , Irã (Geográfico)/epidemiologia , Masculino , Prevalência , Estudos Soroepidemiológicos , EstudantesRESUMO
Mutations within the coding region of hepatitis B surface antigen (HBsAg) have been found naturally in chronic carriers. To characterize the mutations of HBsAg from Iranian chronic carriers who were vaccine and/or medication naive. The surface genes from 360 patients were amplified and directly sequenced. The distribution of amino acid substitutions was classified according to different immune epitopes of the surface protein. All isolates belonged to genotype D. 222 (61.6%) of 360 patients contained at least one amino acid substitution. 404 (74.5%) of 542 amino acid changes occurred in different immune epitopes of HBsAg, of which 112 (27.7%) in 32 residues of B-cell epitopes (62 in the 'a' determinant); 111 (27.4%) in 32 residues of T helper; and 197 (48.7%) in 32 residues inside cytotoxic T lymphocyte (CTL) epitopes. One Th (186-197) and two CTL (28-51 and 206-215) epitopes were found to be hotspot motifs for the occurrence of 213 (52.7%) substitutions. 20 stop codons were identified in different epitopes. There was a significant association between amino acid substitutions and anti-HBe seropositivity; however, the correlation between such changes with viral load and ALT levels was not significant. In chronic hepatitis B virus(HBV) carriers, positive selection in particular outside the 'a' determinant appeared to exert influence on the surface proteins. These changes could be immune escape mutations naturally occurring due to the host immune surveillance especially at the T-cell level.
Assuntos
Portador Sadio/virologia , Epitopos de Linfócito T/genética , Antígenos de Superfície da Hepatite B/genética , Vírus da Hepatite B/genética , Hepatite B Crônica/virologia , Mutação de Sentido Incorreto , Adulto , Substituição de Aminoácidos , Estudos Transversais , DNA Viral/química , DNA Viral/genética , Epitopos de Linfócito T/imunologia , Feminino , Antígenos de Superfície da Hepatite B/imunologia , Vírus da Hepatite B/isolamento & purificação , Humanos , Evasão da Resposta Imune , Irã (Geográfico) , Masculino , Pessoa de Meia-Idade , Análise de Sequência de DNA , Linfócitos T Citotóxicos/imunologiaRESUMO
We describe the specific identification of Leishmania species in Iran using PCR DNA amplification of kDNA. For this purpose, we designed a pair of primers--upstream 5' TCGCAGAACGCCCCTACC 3' and downstream 5'-AGGGGTTGGTGTAAAATAGGC 3'--specific for conserved sequences of kDNA of Leishmania. Using this primer, we identified 3 different amplified fragments from the kDNA of the WHO reference Leishmania species. Two bands at 620 and 850 bp were identified for L. major (MRHO/IR/64/Nadim-1 strain) and only 1 band at 620 bp was identified for L. major (P strain). Therefore, we could differentiate 2 Leishmania species. Also, 1 band at 830 bp was identified for L. tropica (MHOM/Sudan/58/OD strain). We determined the sequence analysis of 2 DNA bands (620 and 850 bp) obtained from kDNA of L. major (MRHO/IR/64/Nadim-1). A total of 157 bp from the 5' site and 234 bp from the 3' site were sequenced and showed about 28% homology between 620 and 850 bp fragments. This technique could amplify as little as 1 fg of DNA and was used to differentiate kDNA samples isolated from Iranian patients with cutaneous leishmaniasis. These data indicate that the primer used for PCR amplification of kDNA is specific and can be used for diagnostic and epidemiological purposes.