Biology subjects

Mackay, I. M.

Publications and source records attributed to Mackay, I. M..

5 recordsLinked to original sources

bioRxiv2019

Measles vaccine virus RNA in children more than 100 days after vaccination

Measles vaccines have been in use since the 1960s with excellent safety and effectiveness profiles. Limited data are available on detection of measles vaccine virus (MeVV) RNA in human subjects following vaccination. Available evidence suggests MeVV RNA can be identified up to 14 days after vaccination, with detection beyond this rare. In routine diagnostic testing, we used two real-time reverse transcription-polymerase chain reaction (RT-rPCR) assays for identifying measles virus (MeV) and MeVV RNA, followed by sequence confirmation of RT-rPCR positives by a semi-nested conventional RT-PCR. We report detection and confirmation of MeVV RNA from the respiratory tract of 11 children between 100 and 800 days after most recent receipt of measles-containing vaccine. These novel preliminary findings emphasize the importance of genotyping all MeV detections and highlight the need for further work to assess whether persistent MeVV RNA represents viable virus and if transmission to close contacts can occur.

microbiology↗

bioRxiv2018

Laboratory Methods Supporting Measles surveillance in Queensland, Australia, 2010-2017

Australia was officially recognised as having eliminated endemic measles circulation in 2014. Maintaining laboratory support for surveillance of vaccine-preventable diseases such as measles is an essential component of reaching and maintaining circulation-free status. Between 2010 and 2017 over 13,700 specimens were tested in our laboratory by real-time RT-PCR (RT-rPCR). Positive extracts from travellers were sequenced as required. Sequences were uploaded to GenBank and demonstrated the wide genetic variation expected from detection of MeV among virus introductions due to global travel. We describe the laboratory workflow employed in our laboratory between 2010 and 2017 for the sensitive detection of MeV infection, supporting high-quality surveillance.

microbiology↗

bioRxiv2018

Genotypic diversity, circulation patterns, and co-detections among rhinoviruses in Queensland, 2001

Rhinoviruses (RVs) occur more frequently than other viruses and more often in people displaying symptoms than in those without. RVs exacerbate chronic airway disease and confound the clinical diagnosis of influenza-like illness. We sought to estimate the spectrum of RV diversity, RV species seasonality and to breakdown RV involvement in respiratory virus co-detections by comprehensive molecular testing of a convenience collection of airway sample extracts from patients with suspected respiratory infections, collected during 2001.\n\nRVs were the most common virus detected. We were able to genotype [~]90% of RV detections, identifying 70 distinct RVs, spanning all three species. RV-Bs were under-represented. We found RV species co-circulated at times, although one species usually dominated. Each species displayed a bimodal distribution.\n\nNotably, RVs and influenza A viruses (IFAV) seldom co-occurred, supporting their roles as primary pathogens of the airway among acutely ill infants. Whether RV circulation has a moderating or controlling effect on the IFAV season or is controlled by it cannot be determined from these data.\n\nDespite the frequent perception that RVs commonly co-occur with another virus, our findings indicated this was not the case. Nearly 80% of RV detections occurred alone. Understanding more about population-level interference between viruses may allow us to harness aspects of it to generate a non-specific antiviral intervention that mimics a putative protective effect.\n\nFor routine respiratory virus screening to best serve the patient, RV testing should be a principal component of any acute respiratory illness testing algorithm throughout the year.

microbiology↗

bioRxiv2017

Presence of Atopy Increases the Risk of Asthma Relapse

ObjectivesIn children with hospitalised and non-hospitalised asthma exacerbations, to: (a) describe the point prevalence of respiratory viruses/atypical bacteria using polymerase chain reaction (PCR) and; (b) evaluate the impact of respiratory viruses/atypical bacteria and atopy on acute severity and clinical recovery.\n\nDesignThis was a prospective study performed during 2009-2011.\n\nSettingThe study was performed in the Emergency Departments of 2 hospitals.\n\nPatients244 children aged 2-16 years presenting with acute asthma to the Emergency Departments were recruited. A nasopharyngeal aspirate and allergen skin prick test were performed.\n\nMain outcome measuresThe outcomes were divided into (a) acute severity outcomes [Australian National Asthma Council assessment, hospitalisation, Functional Severity Scale, acute asthma score, asthma quality of life questionnaires for parents (PACQLQ) on presentation, asthma diary scores (ADS) on presentation and length of hospitalisation] and (b) recovery outcomes (PACQLQ for 21 days, ADS for 14 days and representation for asthma for 21 days).\n\nResultsPCR for viruses/atypical bacteria was positive in 81.7% of children (75.1% human rhinovirus, co-detection in 14.2%). M. pneumoniae and C. pneumoniae were rarely detected. The presence of micro-organisms had little impact on acute asthma or recovery outcomes. Children with atopy were significantly more likely to relapse and represent for medical care by day-14 (OR 1.11, 95%CI 1.00,1.23).\n\nConclusionsThe presence of any viruses is associated with asthma exacerbations but does not appear to influence asthma recovery. In contrast, atopy is associated with asthma relapse. M. pneumoniae and C. pneumoniae are rare triggers of acute asthma in young children.

physiology↗

bioRxiv2017

HPeV-3 predominated among Parechovirus A positive infants in the summer of 2013-2014 in Queensland, Australia.

Parechoviruses (HPeV) are not new viruses and are found in the respiratory tract and central nervous system of children and adults in conjunction with a range of acute illnesses. During an Australian outbreak of HPeV in the summer of 2013, we performed PCR-based screening and genotyping to determine whether ill Queensland infants were infected by HPeV. HPeVs were detected among 25/62 samples, identified as HPeV-3 from 23 that could be genotyped. These variants closely matched those occurring during and after the 2013 HPeV season. The inclusion of HPeV screening should be considered among acutely ill young infants during summer.\n\nHighlightsO_LIHPeV-3 was the most common Parechovirus A genotype in Queensland summer of 2013/14\nC_LIO_LIHPeV testing should be routine among testing of infants with acute CNS - related symptoms\nC_LIO_LIHPeV is a seasonal virus\nC_LIO_LISubgenomic phylogenetic analysis of HPeVs can be confounded by the presence of recombination\nC_LI

microbiology↗