title: What assay is optimal for the diagnosis of measles virus infection? An evaluation of the performance of a measles virus real-time reverse transcriptase PCR using the Cepheid SmartCycler(®) and antigen detection by immunofluorescence.
abstract: BACKGROUND
  Despite the World Health Organization (WHO)-reported elimination of measles in Australia, importation of cases especially in travellers from Asia continues in Sydney, Australia's largest city. Laboratory confirmation supports clinico-epidemiological evidence of measles virus infection, and is needed to establish elimination.
  
  
  OBJECTIVE
  To evaluate the performance of a random access real-time reverse transcriptase polymerase chain reaction (RT-PCR) assay using the moderate complexity SmartCycler(®) platform, and measles antigen detection by immunofluorescence (IFA), for the detection of measles virus in patient samples.
  
  
  METHODS
  One hundred samples comprising nose and throat swabs, nasopharyngeal aspirates and urine, collected from patients with suspected measles were tested in parallel using IFA and nucleic acid testing using the SmartCycler(®) and LightCycler(®) RT-PCR platforms. The LightCycler(®) RT-PCR was used as the reference assay against which the SmartCycler(®) RT-PCR and IFA were compared.
  
  
  RESULTS
  Using the LightCycler(®) RT-PCR, measles virus was detected in 35 clinical samples. There was 100% concordance between the results of the SmartCycler(®) and the LightCycler(®)-based RT-PCR. Measles genotypes detected included B3, D8, and D9. Testing urine in addition to NTS did not improve diagnostic yield. In contrast, the sensitivity and specificity of IFA compared to the reference LightCycler(®) RT-PCR was 34.3% and 96.7%, respectively.
  
  
  CONCLUSIONS
  The performance of the SmartCycler(®) is comparable to the LightCycler(®) for the detection of measles virus. However, IFA had poor sensitivity and should not be used to confirm measles virus infection where nucleic acid testing is available.
authors: Centre for Infectious Diseases and Microbiology Laboratory Services, Institute of Clinical Pathology and Medical Research, Pathology West, Westmead Hospital, Westmead, New South Wales, Australia. Electronic address: kychua@unimelb.edu.au.
authors: Kyra Y L
authors: KYL
authors: Chua
authors: Centre for Infectious Diseases and Microbiology Laboratory Services, Institute of Clinical Pathology and Medical Research, Pathology West, Westmead Hospital, Westmead, New South Wales, Australia.
authors: Kiran
authors: K
authors: Thapa
authors: Communicable Diseases Branch, Health Protection New South Wales, North Sydney, New South Wales, Australia; National Centre for Epidemiology and Population Health, Australian National University, Canberra, Australian Capital Territory, Australia.
authors: Chaturangi M
authors: CM
authors: Yapa
authors: Centre for Infectious Diseases and Microbiology Laboratory Services, Institute of Clinical Pathology and Medical Research, Pathology West, Westmead Hospital, Westmead, New South Wales, Australia.
authors: Lucy K
authors: LK
authors: Somerville
authors: Centre for Infectious Diseases and Microbiology Laboratory Services, Institute of Clinical Pathology and Medical Research, Pathology West, Westmead Hospital, Westmead, New South Wales, Australia; Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Westmead Hospital, Westmead, New South Wales, Australia.
authors: Sharon C-A
authors: SC
authors: Chen
authors: Centre for Infectious Diseases and Microbiology Laboratory Services, Institute of Clinical Pathology and Medical Research, Pathology West, Westmead Hospital, Westmead, New South Wales, Australia; Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Westmead Hospital, Westmead, New South Wales, Australia; Centre for Research Excellence in Critical Infections, University of Sydney, Westmead Hospital, Westmead, New South Wales, Australia.
authors: Dominic E
authors: DE
authors: Dwyer
authors: Communicable Diseases Branch, Health Protection New South Wales, North Sydney, New South Wales, Australia.
authors: Vicky
authors: V
authors: Sheppeard
authors: Centre for Infectious Diseases and Microbiology Laboratory Services, Institute of Clinical Pathology and Medical Research, Pathology West, Westmead Hospital, Westmead, New South Wales, Australia; Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Westmead Hospital, Westmead, New South Wales, Australia; Centre for Research Excellence in Critical Infections, University of Sydney, Westmead Hospital, Westmead, New South Wales, Australia.
authors: Jen
authors: J
authors: Kok
mesh_terms: D000293:Adolescent; D000328:Adult; D000956:Antigens, Viral; D001315:Australia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D005455:Fluorescent Antibody Technique / Q000379:methods / Q000592:standards; D060005:Genotyping Techniques; D006801:Humans; D007223:Infant; D008297:Male; D008457:Measles / Q000175:diagnosis* / Q000453:epidemiology / Q000821:virology*; D008459:Measles virus / Q000145:classification / Q000235:genetics* / Q000276:immunology*; D011933:Reagent Kits, Diagnostic / Q000592:standards; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods / Q000592:standards; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods / Q000592:standards; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D000956:Antigens, Viral; D011933:Reagent Kits, Diagnostic
keywords: Immunofluorescence; Measles virus; RT-PCR