1. PCR – By amplification of the DNA of virus or bacteria present in the patient helps to identify even the concentration of pathogen is very low in the body of the patient. A single stranded DNA or RNA is tagged with a radio active molecule (probe) is allow to hybridized to its complementary DNA in clone of cells followed by detection using auto radiography
Thus the mutated gene can be detected as it will not hybridize with the probe. ELISA – Enzyme linked immune sorbent assay is based on the principle of antigen antibody reaction. Infection by pathogen can be detected by the presence of antigen or by detecting antibodies synthesized against the pathogen.
2. HIV-human immuno deficiency virus.