A negative screening of rare genetic variants in the ADIPOQ and STATH genes in cystic fibrosis.

BACKGROUND: The phenotypic variability in cystic fibrosis (CF) is widely recognized and modulated by environmental and genetic factors, including CFTR pathogenic variants and modifier genes genetic variants. In this context, determining the presence of variants in genes involved in immune response may allow a better understanding of CF variability, mainly in lung disease. Thus, ADIPOQ and STATH genes were selected and the analysis of exons and exon/intron junctions was performed for the determination of variations in its sequence, to determine the possible genetic modulation. METHODS: A total of 49 patients with CF, diagnosed for showing abnormal [chloride] levels in the sweat test, and identification of two pathogenic variants in CFTR categorized as class I and II were included. Genetic sequencing was performed for the identification of variants in the modifier genes. RESULTS: In our analysis, there was absence of rare genetic variants in STATH and ADIPOQ genes associated with the clinical variability. Thus, we are not able to establish an association between the disease severity and rare genetic variants in STATH and ADIPOQ genes, considering exons and exon/intron junctions. CONCLUSIONS: Considering the negative screening for rare genetic variants in ADIPOQ and STATH genes, it may be concluded that these genes are not associated with phenotypic modulation of CF in our population. To understand the modifier genes and its action at CF variability it is essential to promote a better overview of the disease. Also, negative reports can help to direct new studies without the use of unnecessary financial support.

Serotypes, virulence markers and cell invasion ability of Shiga toxin-producing Escherichia coli strains isolated from healthy dairy cattle.

AIM: The occurrence of virulence markers, serotypes and invasive ability were investigated in Shiga toxin-producing Escherichia coli (STEC) isolated from faecal samples of healthy dairy cattle at Rio de Janeiro State, Brazil. METHODS AND RESULTS: From 1562 stx-positive faecal samples, 105 STEC strains were isolated by immuno-magnetic separation (IMS) or plating onto MacConkey agar (MC) followed by colony hybridisation. Fifty (47·6%) strains belonged to nine serotypes (O8:H19, O22:H8, O22:H16, O74:H42, O113:H21, O141:H21, O157:H7, O171:H2 and ONT:H21). The prevalent serotypes were O157:H7 (12·4%), O113:H21 (6·7%) and O8:H19 (5·7%). Virulence genes were identified by polymerase chain reaction (PCR). E-hlyA (77·1%) was the more prevalent virulence marker, followed by espP (64·8%), saa (39%), eae (24·8%) and astA (21·9%). All O157:H7 strains carried the γ (gamma) variant of the locus of enterocyte effacement (LEE) genes and the stx2c gene, while the stx1/stx2 genotype prevailed among the eae-negative strains. None of the eae-positive STEC produced the localized adherence (LA) phenotype in HEp-2 or Caco-2 cells. However, intimate attachment (judged by the fluorescent actin staining test) was detected in some eae-positive strains, both in HEp-2 (23·1%) and in Caco-2 cells (11·5%). Most strains (87·5%) showed 'peripheral association' (PA) adherence phenotype to undifferentiated Caco-2 cells. Twenty-five (92·6%) of 27 strains invaded Caco-2 cells. The highest average value of invasion (9·6%) was observed among the eae-negative bovine strains from serotypes described in human disease. CONCLUSION: Healthy dairy cattle is a reservoir of STEC carrying virulence genes and properties associated with human disease. SIGNIFICANCE AND IMPACT OF THE STUDY: Although reports of human disease associated with STEC are scarce in Brazil, the colonization of the animal reservoir by potentially pathogenic strains offers a significant risk to our population.