Identification of pathogenic Helicobacter species by chaperonin-60 differentiation on plastic DNA arrays.

A microarray method for bacterial species identification based on cpn60 and 16S rDNA hybridization was developed. Specific cpn60 or 16S rDNA oligonucleotides from various Helicobacter or Campylobacter species were printed and immobilized onto a proprietary plastic solid support. Using universal primers, fragments derived from either cpn60 or 16S rDNA genes from single isolates or from a complex human waste sludge DNA sample spiked with Helicobacter pylori were biotinylated and hybridized to the plastic slide. Subsequent querying with a streptavidin-horseradish peroxidase conjugate followed by color development using tetramethylbenzidine resulted in accurate Helicobacter species identification with no cross-hybridization to either the 16S rDNA or the cpn60 sequence of a closely related strain of Campylobacter jejuni. The combination of a nonfluorescence visual detection system with a polymer-based DNA microarray slide has resulted in a molecular tool that should prove useful in numerous applications requiring rapid, low-cost bacterial species identification.

An Outbreak of Human Coronavirus OC43 Infection and Serological Cross-reactivity with SARS Coronavirus.

BACKGROUND: In summer 2003, a respiratory outbreak was investigated in British Columbia, during which nucleic acid tests and serology unexpectedly indicated reactivity for severe acute respiratory syndrome coronavirus (SARS-CoV). METHODS: Cases at a care facility were epidemiologically characterized and sequentially investigated for conventional agents of respiratory infection, SARS-CoV and other human CoVs. Serological cross-reactivity between SARS-CoV and human CoV-OC43 (HCoV-OC43) was investigated by peptide spot assay. RESULTS: Ninety-five of 142 residents (67%) and 53 of 160 staff members (33%) experienced symptoms of respiratory infection. Symptomatic residents experienced cough (66%), fever (21%) and pneumonia (12%). Eight residents died, six with pneumonia. No staff members developed pneumonia. Findings on reverse transcriptase-polymerase chain reaction assays for SARS-CoV at a national reference laboratory were suspected to represent false positives, but this was confounded by concurrent identification of antibody to N protein on serology. Subsequent testing by reverse transcriptase-polymerase chain reaction confirmed HCoV-OC43 infection. Convalescent serology ruled out SARS. Notably, sera demonstrated cross-reactivity against nucleocapsid peptide sequences common to HCoV-OC43 and SARS-CoV. CONCLUSIONS: These findings underscore the virulence of human CoV-OC43 in elderly populations and confirm that cross-reactivity to antibody against nucleocapsid proteins from these viruses must be considered when interpreting serological tests for SARS-CoV.

Novel avian influenza H7N3 strain outbreak, British Columbia.

Genome sequences of chicken (low pathogenic avian influenza [LPAI] and highly pathogenic avian influenza [HPAI]) and human isolates from a 2004 outbreak of H7N3 avian influenza in Canada showed a novel insertion in the HA0 cleavage site of the human and HPAI isolate. This insertion likely occurred by recombination between the hemagglutination and matrix genes in the LPAI virus.

Neisseria meningitidis carriage during an outbreak of serogroup C disease.

During 2001, an outbreak of serogroup C meningococcal disease led to immunization of individuals aged 13-29 years in Abbotsford, British Columbia, Canada. This study addresses the distribution of Neisseria meningitidis carriage in this population and the implications of that distribution for the targeting of the immunization campaign. Pharyngeal swabs were obtained at immunization from 2004 people. Colonies were identified and serogrouped using standard agglutination methods and by PCR. Isolates were characterized using pulsed-field gel electrophoresis (PFGE). The prevalence of N. meningitidis carriage was 153 carriers per 2004 subjects (7.6%; 95% confidence interval, 6.5%-8.9%). Only 6 (4%) of the isolates from these carriers were found to be serogroup C by agglutination or PCR testing, and all of these were from individuals within the age group targeted for immunization. Only 1 of these 6 isolates was found to be identical to the outbreak strain by PFGE. The observation that a virulent strain is not circulating widely suggests the possibility of low background immunity in the population at risk and emphasizes the importance of vaccination in controlling epidemic group C meningococcal disease.