Mic 205 Immune and NAT Testing Ch17 S22 (PDF)

MIC 205 - Microbiology Lecture 15: “It will only hurt for a second! I PROMISE!” Ch. 17: Immune and Nucleic Acid Testing Lecturer: Patrick Daydif Office: UCENT 356 Phone: (602) 496-0599 Email: [email protected] Office Hours: Please refer to Canvas (or by appointment) The...

MIC 205 - Microbiology Lecture 15: “It will only hurt for a second! I PROMISE!” Ch. 17: Immune and Nucleic Acid Testing Lecturer: Patrick Daydif Office: UCENT 356 Phone: (602) 496-0599 Email: [email protected] Office Hours: Please refer to Canvas (or by appointment) The best way to contact me and answer your questions is Face to Face. Testing Serology-study and diagnostic use of antigen-antibody interactions in blood serum Two general diagnostic processes – Use known antibodies (from Biotech) to detect antigens associated with an infectious agent – Use known antigens (from Biotech) to detect specific antibodies in a patient’s blood determines exposure to a specific pathogen Test chosen based on – suspected diagnosis – cost to perform the test – speed with which a result can be obtained Numerous types of serologic test – Agglutination tests – Labeled Antibody tests ELISA Western blot Nucleic acid tests (NAT) Northern Blot Southern bolt RT-PCR 2 Agglutination Tests Agglutination: cross-linking of antibodies with particulate antigens. This results in the clumping of insoluble particles. The test will take a couple of minutes to perform, and the results are easy to interpret with the unaided eye. Used to diagnose diseases caused by – Bacteria Staphylococcus & Streptococcus ssp – Viral Hepatits B – Toxin Tetanus – Drugs – ABO blood typing 3 1 Labeled Antibody Tests (ELISA) Enzyme-Linked ImmunoSorbent Assay – Used to detect either antigens or antibodies from a sample – Use a 2˚ antibody molecule linked to a “label” enzyme that allows for the substrate that is added to be converted to a detectable signal. – Can quantify amounts of antigen or antibody – Easy to perform & can test many samples quickly – Inexpensive – This test will give a number of false positives 4 ELISA Detection of an Antigen Detection of an Antibody Detection of an Hormone 5 Western Blot Test GP 120 GP 40 P24 Technique for detecting antigens in a complex mixture by separation of antigens by size. – (OR detecting one antigen in a complex mixture of proteins) Can detect more types of antibodies and are less subject to misinterpretation than other tests 6 2  Chapter 8 Page 248-249 Nucleic acid tests (NAT) Researcher can detect genetic material by performing molecular techniques. – Southern Blot detects specific DNA sequences from a pathogen. – Northern Blot detects specific RNA sequences from a pathogen. This can help understanding if an individual is infected with a pathogen but does not show any signs or symptoms. Also used to detect known cancer genes Chapter 8 Page 248-249 11 Polymerase chain reaction (PCR) Primers will bind to a specific region of the sample DNA genome and defines the region that will be amplified. 14 RT-PCR Reverse transcription polymerase chain reaction (RT-PCR) is a variation of standard PCR that involves the amplification of specific RNA obtained from small samples. The cycle threshold (Ct): – The number of cycles in real time PCR assay that is need for a positive reaction to be detected. Less cycles to detect a positive reaction = higher viral load. Higher cycles to detect a positive reaction = lower viral load. 15 3 Testing for COVID-19 16 4