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Hayden RT, Su Y, Tang L, Zhu H, Gu Z, Glasgow HL, Sam SS, Caliendo AM. Accuracy of quantitative viral secondary standards: a re-examination. J Clin Microbiol 2024; 62:e0166923. [PMID: 38380932 PMCID: PMC10935634 DOI: 10.1128/jcm.01669-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 01/24/2024] [Indexed: 02/22/2024] Open
Abstract
Interlaboratory agreement of viral load assays depends on the accuracy and uniformity of quantitative calibrators. Previous work demonstrated poor agreement of secondary cytomegalovirus (CMV) standards with nominal values. This study re-evaluated this issue among commercially produced secondary standards for both BK virus (BKV) and CMV, using digital polymerase chain reaction (dPCR) to compare the materials from three different manufacturers. Overall, standards showed an improved agreement compared to prior work, against nominal values in both log10 copies/mL and log10 international unit (IU)/mL, with bias from manufacturer-assigned nominal values of 0.0-0.9 log10 units (either copies or IU)/mL. Standards normalized to IU and those values assigned by dPCR rather than by real-time PCR (qPCR) showed better agreement with nominal values. The latter reinforces prior conclusions regarding the utility of using such methods for quantitative value assignment in reference materials. Quantitative standards have improved over the last several years, and the remaining bias from nominal values might be further reduced by universal implementation of dPCR methods for value assignment, normalized to IU. IMPORTANCE Interlaboratory agreement of viral load assays depends on accuracy and uniformity of quantitative calibrators. Previous work, published in JCM several years ago, demonstrated poor agreement of secondary cytomegalovirus (CMV) standards with nominal values. This study re-evaluated this issue among commercially produced secondary standards for both BK virus (BKV) and CMV, using digital polymerase chain reaction (dPCR) to compare the materials from three different manufacturers. Overall, standards showed an improved agreement compared to prior work, against nominal values, indicating a substantial improvement in the production of accurate secondary viral standards, while supporting the need for further work in this area and for the broad adaption of international unit (IU) as a reporting standard for quantitative viral load results.
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Affiliation(s)
- R. T. Hayden
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Y. Su
- Department of Biostatistics, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - L. Tang
- Department of Biostatistics, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - H. Zhu
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Z. Gu
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - H. L. Glasgow
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - S. S. Sam
- Division of Infectious Diseases, Alpert Medical School of Brown University, Providence, Rhode Island, USA
| | - A. M. Caliendo
- Department of Medicine, Alpert Medical School of Brown University, Providence, Rhode Island, USA
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Lim YZ, Teoh BT, Sam SS, Azizan NS, Khor CS, Nor'e SS, Abd-Jamil J, AbuBakar S. A TaqMan minor groove binder probe-based quantitative reverse transcription polymerase chain reaction for detection and quantification of chikungunya virus. Trop Biomed 2023; 40:313-319. [PMID: 37897164 DOI: 10.47665/tb.40.3.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/29/2023]
Abstract
Chikungunya virus (CHIKV) is a mosquito-borne alphavirus with widespread distribution across the globe. Since 2016, CHIKV re-emerged in several countries including Indian subcontinent and Southeast Asia. A proper diagnostic tool for early diagnosis of CHIKV infection is crucial to facilitate patient management and control virus transmission at the earliest stage of outbreak. Therefore, a TaqMan minor groove binder (MGB) probe-based quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay was developed to detect and quantify the CHIKV. The primers and probe were designed based on a conserved genomic region of 730 global CHIKV sequences that is located between nsP1 and nsP2 genes. The nucleotide mismatches of primers and probe with 730 global CHIKV sequences and 13 alphaviruses were then analysed in silico. In this study, the last 5 nucleotides at 3' end of primers and 5' end of probe were considered to be the critical regions for priming. In silico analysis revealed that the critical regions of primers and probe were at least 99.6% matched with the 730 global CHIKV sequences. Besides, the primers and probe showed at least 5/20 (25.0%) and 4/17 (23.5%) nucleotide mismatches with 13 alphaviruses respectively. The amplification efficiency of qRT-PCR assay was 100.59% (95% CI= 93.06, 109.33) with a R2 score of 0.957. Its limit of detection (LOD) at 95% probability level was 16.6 CHIKV RNA copies (95% CI= 12.9, 28.9). The qRT-PCR assay was specific to CHIKV without cross-reacting with all dengue virus serotypes, Getah virus, Tembusu virus and Zika virus. The diagnostic results of qRT-PCR assay were perfectly agreed (k=1.000, p=0.003) with a commercial trioplex assay, with sensitivity of 100% (95% CI= 61, 100) and specificity of 100% (95% CI= 44, 100). Overall, the developed qRT-PCR assay is ideal for rapid, sensitive and specific detection as well as quantification of CHIKV.
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Affiliation(s)
- Y Z Lim
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Centre of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
- Institute for Advanced Studies, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - B T Teoh
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Centre of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - S S Sam
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Centre of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - N S Azizan
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Centre of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - C S Khor
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Centre of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - S S Nor'e
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Centre of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - J Abd-Jamil
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Centre of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - S AbuBakar
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Centre of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
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Chin KL, Teoh BT, Sam SS, Loong SK, Tan KK, Azizan NS, Lim YK, Khor CS, Nor'e SS, Abd-Jamil J, AbuBakar S. Development of a TaqMan minor groove binding probe-based quantitative reverse transcription polymerase chain reaction for the detection and quantification of Zika virus. Trop Biomed 2022; 39:518-523. [PMID: 36602210 DOI: 10.47665/tb.39.4.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Zika virus (ZIKV) infection has emerged as a global health concern following epidemic outbreaks of severe neurological disorders reported in Pacific and Americas since 2016. Therefore, a rapid, sensitive and specific diagnostic test for ZIKV infection is critical for the appropriate patient management and the control of disease spread. A TaqMan minor groove binding (MGB) probe-based quantitative reverse transcription-polymerase chain reaction (qRT-PCR) assay was developed based on the conserved sequence regions of 463 ZIKV NS2B genes. The designed ZIKV qRT-PCR assay was evaluated for its detection limit, strain coverage and cross-reactivity. We further assessed the clinical applicability of qRT-PCR assay for ZIKV RNA detection using a total 18 simulated clinical specimens. The detection limit of the qRT-PCR assay was 11.276 ZIKV RNA copies at the 95% probability level (probit analysis, p<= 0.05). Both Asian and African ZIKV strains were detected by the qRT-PCR assay without cross-reacting with DENV-1, DENV-2, DENV-3, DENV-4, CHIKV, JEV, LGTV, GETV and SINV. The qRT-PCR assay demonstrated a perfect agreement (k = 1.000, P < 0.001) with the reference assay; the sensitivity and specificity of the qRT-PCR assay were 100% (95% CI= 79.6-100) and 100% (95% CI= 43.9-100) respectively. The qRT-PCR assay developed in this study is a useful diagnostic tool for the broad coverage detection and quantification of both the Asian and African ZIKV strains.
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Affiliation(s)
- K L Chin
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Center of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia.,Institute for Advanced Studies, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - B T Teoh
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Center of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - S S Sam
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Center of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - S K Loong
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Center of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - K K Tan
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Center of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - N S Azizan
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Center of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - Y K Lim
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Center of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - C S Khor
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Center of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - S S Nor'e
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Center of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - J Abd-Jamil
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Center of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - S AbuBakar
- Tropical Infectious Diseases Research and Education Centre (TIDREC), Higher Institution Center of Excellence (HICoE), Universiti Malaya, 50603 Kuala Lumpur, Malaysia.,Department of Medical Microbiology, Faculty of Medicine, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
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Hayden RT, Su Y, Boonyaratanakornkit J, Cook L, Gu Z, Jerome KR, Pinsky BA, Sam SS, Tan SK, Zhu H, Tang L, Caliendo AM. Matrix Matters: Assessment of Commutability among BK Virus Assays and Standards. J Clin Microbiol 2022; 60:e0055522. [PMID: 35997500 PMCID: PMC9491175 DOI: 10.1128/jcm.00555-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 07/18/2022] [Indexed: 11/20/2022] Open
Abstract
Quantitative testing of BK virus (BKPyV) nucleic acid has become the standard of care in transplant patients. While the relationship between interassay harmonization and commutability has been well characterized for other transplant-related viruses, it has been less well studied for BKPyV, particularly regarding differences in commutability between matrices. Here, interassay agreement was evaluated among six real-time nucleic acid amplification tests (NAATs) and one digital PCR (dPCR) BKPyV assay. Differences in the commutability of three quantitative standards was examined across all assays using a variety of statistical approaches. Panels, including 40 samples each of plasma and urine samples previously positive for BKPyV, together with one previously negative plasma sample and four previously negative urine samples, were tested using all assays, with each real-time NAAT utilizing its usual quantitative calibrators. Serial dilutions of WHO, National Institute for Standards and Technology (NIST), and commercially produced (Exact/Bio-Rad) reference materials were also run by each assay as unknowns. The agreement of the clinical sample values was assessed as a group and in a pairwise manner. The commutability was estimated using both relativistic and quantitative means. The quantitative agreement across assays in the urine samples was within a single log10 unit across all assays, while the results from the plasma samples varied by 2 to 3 log10 IU/mL. The commutability showed a similar disparity between the matrices. Recalibration using international standards diminished the resulting discrepancies in some but not all cases. Differences in the sample matrix can affect the commutability and interassay agreement of quantitative BKPyV assays. Differences in commutability between matrices may largely be due to factors other than those such as amplicon size, previously described as important in the case of cytomegalovirus. Continued efforts to standardize viral load measurements must address multiple sources of variability and account for differences in assay systems, quantitative standards, and sample matrices.
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Affiliation(s)
- R. T. Hayden
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Y. Su
- Department of Biostatistics, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | | | - L. Cook
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, USA
| | - Z. Gu
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - K. R. Jerome
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, USA
- Vaccine and Infectious Diseaese Division, Fred Hutchinson Cancer Center, Seattle, Washington, USA
| | - B. A. Pinsky
- Department of Pathology, Stanford University School of Medicine, Stanford, California, USA
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California, USA
| | - S. S. Sam
- Division of Infectious Diseases, Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA
| | - S. K. Tan
- Department of Pathology, Stanford University School of Medicine, Stanford, California, USA
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California, USA
| | - H. Zhu
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - L. Tang
- Department of Biostatistics, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - A. M. Caliendo
- Division of Infectious Diseases, Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA
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Abstract
Inheritance of polymorphisms in the interleukin (IL)-10 promoter and IL-12B genes, which influence cytokine production and activities, may define the balance in T helper response in infection and autoimmune diseases. In the present study, we investigated the distribution of the IL-10 promoter and IL-12B gene polymorphisms in a multiethnic Malaysian population. Overall, our findings suggest that the IL-12B and IL-10 -592 genotypes were distributed homogenously across all major ethnic groups, including Malays, Chinese, and Indians, except for polymorphisms at IL-10 -1082. At this gene locus, the ethnic Chinese showed a significantly lower allele frequency of -1082G (2.1%) compared to the Malay (12.2%) and Indian (15.3%) populations. Results for the IL-12B and IL-10 gene polymorphisms were consistent with those reported for the Asian population, but markedly different from those of the African and Caucasian populations. Our findings suggest that there are specific genetic variations between different ethnic groups, which should be examined in all gene population-based association studies.
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Affiliation(s)
- S S Sam
- Tropical Infectious Diseases Research and Education Center, Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - B T Teoh
- Tropical Infectious Diseases Research and Education Center, Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - S AbuBakar
- Tropical Infectious Diseases Research and Education Center, Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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Hoh BP, Sam SS, Umi SH, Mahiran M, Nik Khairudin NY, Rafidah Hanim S, Abubakar S. A novel rare copy number variant of the ABCF1 gene identified among dengue fever patients from Peninsular Malaysia. Genet Mol Res 2014; 13:980-5. [PMID: 24634119 DOI: 10.4238/2014.february.19.9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Copy number variation (CNV) is a form of genetic variation in addition to single nucleotide polymorphisms. The significance of CNV in the manifestation of a number of diseases is only recently receiving considerable attention. We genotyped 163 dengue patients from Peninsular Malaysia for genes possibly linked to dengue infection using quantitative real-time PCR. Here, we report a serendipitous discovery of a novel rare CNV of the ABCF1 gene among the dengue patients. Among these patients, two had a gain of 1 copy (CN = 3) and one had lost 1 copy (CN = 1), indicating that a rare CNV of the ABCF1 gene was detected among dengue patients from Peninsular Malaysia. Although the gene is suspected to regulate inflammatory responses and pathogen-induced cytokine storm, its relevance to dengue requires further investigation.
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Affiliation(s)
- B P Hoh
- Institute of Medical Molecular Biotechnology, Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh Campus, Jalan Hospital, Sungai Buloh, Selangor, Malaysia
| | - S S Sam
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - S H Umi
- Institute of Medical Molecular Biotechnology, Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh Campus, Jalan Hospital, Sungai Buloh, Selangor, Malaysia
| | - M Mahiran
- Department of Medicine, Hospital Kota Bharu, Kelantan, Malaysia
| | | | - S Rafidah Hanim
- Department of Microbiology and Parasitology, School of Medical Science, Health Campus, Universiti Sains Malaysia, Kota Bharu, Kelantan, Malaysia
| | - S Abubakar
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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