Nucleic Acid COVID-19 Tests
The JABSOM Tropical Medicine Clinical Lab will utilize a different testing approach than the testing methods employed at the Department of Health or private laboratories in Hawaiʻi. This approach was chosen specifically to avoid competing with State or private labs in Hawaiʻi for scarce testing supplies and materials.
What type of tests are available for COVID-19?
COVID-19 is the disease caused by the SARS-CoV-2 virus. The TMCL has been authorized by the CLIA Program of the Hawaiʻi Department of Health to perform nucleic acid amplification tests (NAAT). NAAT tests are molecular tests that detect the virus’s genetic material in a sample that typically comes from a patient’s respiratory system including the nasopharynx and secretions such as sputum or saliva. Once the specimen is collected, it is delivered to a clinical lab. The SARS-CoV-2 virusʻs genetic material is RNA and once it is purified, 4 genes are amplified to determine how much of the virus is present in the patient sample.
U.S. FDA-authorized NAAT tests for SARS-CoV-2 meet the Emergency Use Authorization statutory standard, and based on the current available data, are highly accurate.
We have selected the TaqPath COVID-19 CE-IFV RT-PCR kits produced by ThermoFisher and run on the Applied Biosystems QuantStudioTM 5 Real-Time PCR System. The kit can be used by clinical and public health laboratories to quickly evaluate up to 94 patient specimens in under 3 hours. The kit is approved for use with RNA extracted from nasopharyngeal swabs, nasopharyngeal aspirate (nasal aspirate), and bronchoalveolar lavage (BAL) from patients at risk of exposure to SARS-CoV-2 or with signs and symptoms of COVID-19.
Information and graphics from ThermoFisher website. Note that we are using the QuantStudioTM 5 Real-Time PCR System instead of the 7500 system.
The Tropical Medicine Clinical Laboratory uses the Luminex xMAP® SARS-CoV-2 Multi-Antigen IgG Assay for serology testing. This is a multiplex, microsphere-based assay for the detection of IgG antibodies to SARS-CoV-2 in human serum. The xMAP SARS-CoV-2 Multi-Antigen IgG Assay is intended for use as an aid in identifying individuals with an adaptive immune response to SARS-CoV-2, indicating recent or prior infection. Currently it is unknown for how long antibodies persist following infection and if the presence of antibodies confers protective immunity. IgG antibodies to SARS-CoV-2 are generally detectable in blood several days after initial infection.
The xMAP® SARS-CoV-2 Multi-Antigen IgG Assay detects antibodies against the SARS-CoV-2 S1 subunit of the spike protein (S1), the Receptor-Binding Domain (RBD) of the spike protein, and the nucleocapsid protein (N) in serum samples from patients suspected of past SARS-CoV-2 infections. Specific antigen-coupled beads (S1, RBD, and N) are recognized and distinguished by the Luminex instrument based on their specific fluorescence spectral signature and quantified based on their signal intensity. The internal control microspheres include: (1) IgG Detection Control; monitors for sample addition and addition of IgG Detection Reagent, (2) Background Control; monitors for non-specific binding, and (3) IgM and IgA Detection Controls; monitor for antibody isotype specificity. The diagrams below depict the virus antigens to which the antibodies bind and the assay procedures.
The solid dark red circles depict the beads that are coupled with antigen (yellow oblong shapes). The Y shaped figures represent various types of antibodies, including antibodies to the N, RBD, and S1 antigens. The magenta star-shaped antibody-coupled (antibody to human IgG) figures in the diagram below depict the fluorogenic detection reagent.