Abstract
In recent years, nucleic acid tests for detection of measles virus RNA have been widely applied in laboratories belonging to the measles surveillance system of China. An external quality assessment program was established by the National Center for Clinical Laboratories to evaluate the performance of nucleic acid tests for measles virus. The external quality assessment panel, which consisted of 10 specimens, was prepared using armored RNAs, complex of noninfectious MS2 bacteriophage coat proteins encapsulated RNA of measles virus, as measles virus surrogate controls. Conserved sequences amplified from a circulating measles virus strain or from a vaccine strain were encapsulated into these armored RNAs. Forty-one participating laboratories from 15 provinces, municipalities, or autonomous regions that currently conduct molecular detection of measles virus enrolled in the external quality assessment program, including 40 measles surveillance system laboratories and one diagnostic reagent manufacturer. Forty laboratories used commercial reverse transcription-quantitative PCR kits, with only one laboratory applying a conventional PCR method developed in-house. The results indicated that most of the participants (38/41, 92.7%) were able to accurately detect the panel with 100% sensitivity and 100% specificity. Although a wide range of commercially available kits for nucleic acid extraction and reverse transcription polymerase chain reaction were used by the participants, only two false-negative results and one false-positive result were generated; these were generated by three separate laboratories. Both false-negative results were obtained with tests performed on specimens with the lowest concentration (1.2 × 104 genomic equivalents/mL). In addition, all 18 participants from Beijing achieved 100% sensitivity and 100% specificity. Overall, we conclude that the majority of the laboratories evaluated have reliable diagnostic capacities for the detection of measles virus.
Highlights
Measles virus (MeV) is a single-stranded, negative-sense RNA virus that belongs to the genus Morbillivirus in the family Paramyxoviridae [1]
To calibrate the number of MeVC RNAs and MeV vaccine strain Shanghai-191 (MeVV) RNAs to an international unit (IU) value, we designed two 1,002-bp chimeric sequences to include the HCV 5’UTR region (a 368-bp target sequence amplified from pNCCL-HCV archived in our laboratory [10]) and reverse transcription polymerase chain reaction (RT-PCR) targets
Armored RNAs were observed by transmission electron microscopy, as shown in S1C Fig; the diameter of the MS2 virus-like particles was approximately 30 nm
Summary
Measles virus (MeV) is a single-stranded, negative-sense RNA virus that belongs to the genus Morbillivirus in the family Paramyxoviridae [1]. Measles is immunization-preventable, it remains a threat to non-vaccinated children and adults. Since 1986, a two-dose, routine measles immunization schedule has been used in China, with the goal of eliminating measles. An outbreak of measles (23 people infected) in Beijing in early 2015 served as a reminder that measles remains a significant health threat in China [4], despite the country’s aim to eliminate measles by 2012 [5]. China contributes greatly to the heavy burden of measles in the WHO Western Pacific Region [6], highlighting the importance of an effective surveillance system and enhanced vaccination strategies. Sensitive and specific assays can greatly enhance the implementation of measles surveillance
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