Evaluation of a histocompatibility antigen related to hepatitis B virus in patients with hepatocellular carcinoma in the western Brazilian Amazon.

Hepatocellular carcinoma is an infection of variable incidence that can be caused by hepatitis B virus (HBV), which is endemic in the Amazon region. The diagnosis of HBV can be performed through the use of serum markers such as the hepatitis B surface antigen. The chronic HBV can cause mutagenesis and carcinogenesis, being the susceptibility of infection due to allele human leukocyte antigen (HLA). Thus, we evaluated the clinical, molecular and laboratory profile (histocompatibility complex) of HBV in 22 patients with hepatocellular carcinoma in Amazonia, including 18 males and 4 females, using a blood sample for generic HLA class II. The results showed increased frequency of disease evolution in adults between 25 and 64 years old, who comprised 19 of the 22 patients studied. Most patients (16/22) presented high levels of alpha-fetoprotein and transaminases (14/22). The most common HLA alleles were DRB1 04 (8/44), DRB1 08 (9/44), DRB 03 (16/44), and DQB1 04 (9/44). When we compared specific phenotype frequencies of HLA-DRB1 between patients and controls, we found that patients had a significantly higher frequency of allele DRB1 08 and a significantly lower frequency of DRB1 07 and DRB1 12 compared to previous studies on Asian and Amazonian populations suggesting ethnic differences. We suggest that alleles HLA-DRB 08, HLA-DRB 03 and HLA-DQB1 04 may be risk factors for hepatocellular carcinoma in Amazon.

Phenotypic and genotypic characterisation of Escherichia coli strains serogrouped as enteropathogenic E. coli (EPEC) isolated from pasteurised milk.

Fifty-six Escherichia coli strains, serogrouped as EPEC, isolated from three different brands of pasteurised milk commercialised in Rio de Janeiro, Brazil, were tested for enteropathogenicity markers. Most of the strains (71.4%) were adherent to HEp-2 cells. The adherent strains were distributed among 7 EPEC serogroups (O26, O55, O111, O114, O125, O127, O128, O158). Although almost half of these strains (33.9%) presented unrecognisable adherence phenotypes, classical adherence patterns (localised-like, aggregative and diffuse adherence) described for E. coli and epidemiologically associated with diarrheagenic strains were observed. None of the strains showed typical localised adherence, usually associated with EPEC strains, but 4 of them displayed a localised-like adherence (LAL) phenotype, characterised by fewer and less compact microcolonies but that is still associated with diarrheagenic strains as well as strains of non-human origin. Indeed, 3 of these 4 strains were able to elicit the attaching-effacing lesion (FAS-positive), the central feature of EPEC pathogenesis, and hybridised with bfpA and eae DNA probes. The other LAL-positive strain hybridised with the bfpA probe but gave negative results for the eae probe and FAS assays. Interestingly, all LAL-positive strains produced amplicons of 200 bp in the PCR for bfpA, instead of the expected 326 bp fragment. PCR reactions for stx1 and stx2, two shiga-toxin-encoding genes, gave negative results. Typing of LEE-associated genes by PCR showed the profile eae (beta), tir (beta), espA (alpha) and espB (alpha) for one of the LAL-positive strain. The most prevalent adherence phenotype was the aggregative pattern which is observed in strains epidemiologically associated with persistent diarrhea. Additionally, one strain promoted complete detachment of the Hep-2 cell monolayer after 3 h of infection which might be related to the production of citotoxins, a feature that has been increasingly observed in clinical strains. The possession of EPEC-related O and H antigens is no longer deemed an essential characteristic of true pathogenic EPEC strains, emphasising the importance of routinely screen for virulence markers in E. coli strains isolated from foods. Our results are in accordance with data from the literature that demonstrate that environmental strains display atypical features but yet are capable of eliciting the classical A/E lesion and thus must be considered as potentially pathogenic. Further, our results demonstrate the potential of pasteurised milk as a vehicle for transmission of diarrheagenic E. coli in Brazil.