Low frequency of protease codon 35 amino acid insertion in sequences from treated HIV-1 infected individuals from Buenos Aires, Argentina
I. Zapiola1, S. Fernandez Giuliano1, F. Gonzalez1, O. Garcia Messina2, A. Rodriguez2, D. Cecchini3, C. Rodriguez3, M.B. Bouzas1
1Hospital Muñiz, Unidad de Virologia, Buenos Aires, Argentina, 2Hospital Piñero, Infectologia, Buenos Aires, Argentina, 3Hospital Argerich, Infectologia, Buenos Aires, Argentina
Background: Prevalence of amino acid insertions in the protease (PR) region ranging 0.1% to 4.55% has been reported. We investigated the presence of PR codon 35 amino acid insertion among sequences from treated HIV-1 infected individuals.
Methods: Plasma samples from 594 treated HIV-1 infected individuals between January 2007 and January 2010 were analyzed for drug resistance mutations. The entire PR and partial retrotranscriptase (RT) of the pol gene were sequenced by Trugene HIV-1 Genotyping Kit (SIEMENS) following manufacturer´s instructions. Viral load (VL), prior and current antiretroviral regimen were evaluated.
Results: VL ranged from 260 to >500000 copies/ml (mean= 68297 copies/ml). 295/594 (49,7%) patients had at least one protease inhibitor (PI) in the present regimen, 168/594 (28.3%) patients had at least one PI in the past and 131/594 (22%) never received PIs. PR codon 35 amino acid insertion was detected in 2/594 (0.34%) of the sequences analyzed and belonged to patients without a history of PI exposure. One sample belonged to a 35 year-old pregnant woman infected since 2005 with a VL of 1543 copies/ml. This strain harboured a single aspartic acid (GAC) insertion (E35E_D) between PR codons 35 and 36. The other sample belonged to a 48 year-old man diagnosed in 2006 with a VL of 27100 copies/ml. In this case the sequence carried an aspartic acid mutation (GAC) in codon 35 and aspargine (AAC) insertion (E35D_N). Both patients received AZT, 3TC and EFV, the subtype evaluated with the Stanford University Database was BF and heterosexual transmission was found to be the route of infection.
Conclusions: We found a low frequency (0.34%) of PR codon 35 insertion among treated HIV-1 infected individuals, being the first report from Argentina. So far we know this is the first report of E35D_N insertion and its clinical impact requires further investigation.
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