Enterotoxigenic Escherichia coli (ETEC) is one of the major causes of neonatal calf diarrhea. Almost all ETEC bacteria are known to adhere to receptors on the small intestinal epithelium via their fimbriae, (F5 (K99) and F41).This study was undertaken to investigate the phenotypic and genotypic screening of virulence genes in E. coli K99 and F41. During January 2008 to December 2009, 298 diarrheic neonatal calves at 1-30 days old were studied by multiplex PCR, isolation, and serological grouping. Of the 298 diarrheic samples, 268 E. coli were isolated, of which 16 samples (5.3%) were positive for having the F5 (K99) fimbrial gene by PCR while all of the E. coli isolates also carried F41 fimbrial genes. Twenty-five percent of the isolates were proven not to be toxigenic as they did not possess the STa enterotoxin gene.
Enterohaemorrhagic Escherichia coli constitute a subset of serotypes (E. coli O157 and some other serogroups) of Shiga toxin-producing E. coli firmly associated with severe human illnesses like bloody diarrhoea and haemolytic uraemic syndrome. Escherichia coli O157:H7 is a zoonotic pathogen. They rarely cause disease in animals, live in the intestines of healthy sheep and ruminants are recognized as their main natural reservoir, so they can contaminate meat during slaughtering practices. The purpose of this study was epidemiological survey on the occurrence of E. coli O157:H7 in healthy sheep in Shiraz-Iran. Polymerase Chain Reaction (PCR) assay was developed to detect the Stx2 gene the only bacterial factor that has been associated with more severe disease. During a period of 7 months (December 2005 to June 2006), 153 slaughtered sheep at Shiraz slaughterhouse, were randomly selected and examined for surface carriage of E. coli O157:H7 by conventional plating and Stx2 gene detection by PCR technique. E. coli O157:H7 was found in 6(3.92%) of 153 sheep. The bacteria were isolated from 5(3.34%) of 114 and 1(2.63%) of 38 sheep two or under two and more than 2 years old, respectively (p = 0.5). The contamination rate might vary depending on season, age and infection time. The higher frequency for younger animals may be due to differences in the composition of the gastrointestinal flora resulting from differences in diet. This is the first report of the presence of E. coli O157:H7 in sheep from Iran.
Background: Influenza is a major cause of morbidity and mortality worldwide. Each year, influenza viruses cause epidemics by evading pre-existing immunity through mutations in major surface glycoprotein hemagglutinin, which helps in attachment of the viral strain on the host cell surface. Due to high mutation rate, only currently circulating strains should be used in the vaccines.
Introduction: Influenza is a contagious acute viral disease of the respiratory tract that causes fever, headache, muscle aches and cough. One of the unique features of influenza virus is antigenic variation in viral protein neuraminidase (NA) which causes emergence of new virus variants. NA is responsible for the release and spread of progeny virions. Due to the continuous changes of NA genes, vaccine strains must be re-selected annually. Methods: Complete NA amino acid sequences of 97 strains circulating from 2006 to 2013 in Iran were downloaded from NCBI. The sequences were edited and classified by the year of isolation and their diversity and important changes as well as changes in the predicted ligand binding sites and their resistance to anti-NA drugs, were analyzed. Bioinformatics software such as MEGA6.0, BioEdit, DNAsisMAX and DNAstar were used for the sequence alignments and phylogenetic analyses. Web-based analysis such as SWISS-MODEL, Phyre2 and 3DLigandSite were used for evaluation of the second and third protein structures and prediction of the ligand binding sites. Results: The results showed that 2009 could be considered as an important transition year which caused to classify the isolates into two different distinct groups. This shows the importance of changes made during possible mutations in the genomic structure of the virus which have made it antigenically different from the previous years. Anti-NA drug resistance was observed in 2009. This pandemic strain has become dominant in the following years and is used as a standard vaccine strain from 2010 onwards. Conclusion: The results obtained in this study can aid in better understanding of the antigenic evolution of H1N1 influenza viruses and can potentially accelerate the selection of the vaccine strains.
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