HIV recombinants are increasingly observed worldwide particularly in Asia. This leads to intra and inter host viral variation and may facilitate the emergence of multidrug resistance. Genotype resistance testing (GRT) has therefore been a useful tool in guiding therapy. In recent years, the development of an inexpensive and sensitive direct-sequencing-based in-house GRT has enabled routine testing at Singapore's National University Hospital (NUH).
We conducted a retrospective study to determine the pattern of HIV-1 subtypes and drug-resistance mutations (DRMs). GRT data obtained from the Molecular Diagnosis Centre was reviewed and compiled for newly-diagnosed, treatment-na´ve, HIV-1 infected patients presenting to NUH from January 2013 to December 2014.
A total of 123 patients were identified in this study, of whom 114 (92.7%) were male.
The REGA tool was used to determine the subtypes (see Figure 1). The Circulating Recombinant Form (CRF) strain CRF01_AE was more prevalent (59.3%) than the pure subtypes (35.8%). The majority of the pure subtypes were B (n=40), followed by G (n=3) and C (n=1). There was a small number of indeterminate sequences (6, 4.9%) where Stanford was used instead with resulting sequences: subtype B (n=2), CRF02_AG (n=2) and CRF02_AE (n=2). Consistent with current epidemiological trends in Asia, CRF01_AE and subtype B appear to be the main circulating strains.
Of the 123 samples, only 46 (37.4%) were fully susceptible to anti-retroviral therapy (see Figure 1). Among those with DRMs, 53 (43.1%) were PI-resistant, 44 (35.8%) RTI-resistant, and 20 (16.3%) were resistant to both. A total of 113 DRMs (59 PR and 54 RT) were isolated. The in-house assay detected 17/36 PR and 16/32 RT drug-resistance associated codons listed in the HIV-1 DRMs 2014 update. Furthermore, E35G (decreased NFV/TPV susceptibility) and Y318F (decreased NVP/EFV susceptibility) were detected. The majority of the DRMs (69.1%) were found in RT positions 106, 138 and 179, and PR positions 10 and 71.
The landscape of HIV epidemiology in Singapore has changed in the last decade. áThe recombinant strain CRF01_AE predominates and a significant number of treatment-na´ve patients are found to have primary genotypic resistance.
Figure 1: Overview of HIV-1 subtypes and DRMs in treatment-na´ve patients at NUH Singapore
S. A. Woon,
S. Archuleta, None
E. S. C. Koay, None
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