HIV drugs resistance assay

Q: Which are the two fundamental types of HIV drug resistance assay?

Answer: GENOTYPIC and PHENOTYPIC

As medical science is fast integrating precision medicine, drug therapy is fast getting based on resistance assay for each patient. Studies have shown that proper resistance assay improves management as well as survival. There are two major types of assays in this regard:

1. Genotypic: It provides information regarding specific drug resistance mutations in the regions of the HIV genome encoding protease, reverse transcriptase, and integrase. Results are reported as individual mutations. It reports each antiretroviral drug as

• susceptible
• possibly resistant, or
• resistant

2. Phenotypic: This principle is similar to bacteriologic methods, providing an inhibitory concentration required to inhibit in vitro growth by 50 percent (IC50) compared with virus replication without a drug. It aggregates the acquired drug mutations in a patient's viral strain. This is reported as a fold-change in drug susceptibility of the patient sample compared with a laboratory reference strain without resistance.

#ID

#pharmacology

References: 

1. Günthard HF, Calvez V, Paredes R, Pillay D, Shafer RW, Wensing AM, Jacobsen DM, Richman DD. Human Immunodeficiency Virus Drug Resistance: 2018 Recommendations of the International Antiviral Society-USA Panel. Clin Infect Dis. 2019 Jan 7;68(2):177-187. doi: 10.1093/cid/ciy463. PMID: 30052811; PMCID: PMC6321850.

2. Van Vaerenbergh K. Study of the impact of HIV genotypic drug resistance testing on therapy efficacy. Verh K Acad Geneeskd Belg. 2001;63(5):447-73. PMID: 11813503.