TREAT Asia Quality Assessment Scheme (TAQAS) to standardize the outcome of HIV genotypic resistance testing in a group of Asian laboratories

Abstract

The TREAT Asia (Therapeutics, Research, Education, and AIDS Training in Asia) Network is building capacity for Human Immunodeficiency Virus Type-1 (HIV-1) drug resistance testing in the region. The objective of the TREAT Asia Quality Assessment Scheme - designated TAQAS - is to standardize HIV-1 genotypic resistance testing (HIV genotyping) among laboratories to permit rigorous comparison of results from different clinics and testing centres. TAQAS has evaluated three panels of HIV-1-positive plasma from clinical material or low-passage, culture supernatant for up to 10 Asian laboratories. Laboratory participants used their standard protocols to perform HIV genotyping. Assessment was in comparison to a target genotype derived from all participants and the reference laboratory's result. Agreement between most participants at the edited nucleotide sequence level was high (>98%). Most participants performed to the reference laboratory standard in detection of drug resistance mutations (DRMs). However, there was variation in the detection of nucleotide mixtures (0-83%) and a significant correlation with the detection of DRMs (p<0.01). Interpretation of antiretroviral resistance showed approximately 70% agreement among participants when different interpretation systems were used but >90% agreement with a common interpretation system, within the Stanford University Drug Resistance Database. Using the principles of external quality assessment and a reference laboratory, TAQAS has demonstrated high quality HIV genotyping results from Asian laboratories.

Fig. 1

Level of agreement between the participants’ entire edited nucleotide sequences and the target genotype (TG) in up to three TAQAS. Most participants reported >98% agreement with the TG (grey bars) (10 of 10 participants that tested TAQAS 1,9 of 12 participants that tested TAQAS 2, and 10 of 12 participants that tested TAQAS 3). Most of the differences reported from the TG were partial differences (black bars). Less than 0.5% of the differences reported from the TG were complete differences (hatched bars) for the majority of participants (all participants that tested TAQAS 1 and 3, and 8 of 12 participants that tested TAQAS 2).

Fig. 2

The participants’ detection of drug resistance mutations (DRMs) at nucleotide sequences positions associated with ARV drug resistance in the target genotype (TG). Most participants reported >80% of the DRMs present in the TG as mutations (grey bars) or nucleotide mixtures of wildtype and mutation (black bars). Participants’ sequences varied in the percent of DRMs reported as nucleotide mixtures (black bars). Some participants reported wildtype at >20% of the nucleotide sequences positions associated with ARV drug resistance in the TG (hatched bars).

Fig. 3

The participants’ detection of nucleotide mixtures over the entire sequence in three TAQAS. Most (8 of 10) participants increased their detection of nucleotide mixtures in TAQAS 2 compared with TAQAS 1. Ten participants detected proportionally less nucleotide mixtures in TAQAS 3 compared with their detection of nucleotide mixtures in TAQAS 2. Three participants (ID: 2, 5 and 12) consistently detected low levels of or no nucleotide mixtures in all the TAQAS tested.