Sistema FMUSP-HC: Faculdade de Medicina da Universidade de São Paulo (FMUSP) e Hospital das Clínicas da FMUSPMOREIRA, Regina CeliaSANTOS, Ana Paula de TorresLISBOA-NETO, GasparMENDES-CORREA, Maria Cassia JacinthoLEMOS, Marcilio FigueiredoMALTA, Fernanda MelloSANTANA, RAbia Anita FerrazDASTOLI, Gregorio Tadeu FernandoCASTRO, Vanessa Fusco Duarte dePINHO, Joao Renato Rebello2018-11-212018-11-212018ARCHIVES OF VIROLOGY, v.163, n.10, p.2757-2764, 20180304-8608https://observatorio.fm.usp.br/handle/OPI/29652Hepatitis C (HCV)-infected patients are treated with direct-acting antiviral agents (DAAs) in highly effective, well-tolerated, all-oral regimens. However, naturally occurring resistance-associated amino acid substitutions (RASs) may be selected during treatment. This study aimed to screen naturally occurring RASs NS3/NS4A inhibitors (PIs). Samples were obtained from DAA naive patients, living in Sao Paulo state, Brazil. Screening for RASs in the HCV NS3 region was conducted in 859 samples from HCV-infected patients, of which 425 and 434 samples were subtype la and lb, respectively. HCV-RNA was extracted, amplified, and sequenced. The overall prevalence of RASs to HCV PIs was 9.4%. The following RASs were observed in HCV-1a subtype infected patients: V36L (2.6%), T54S (1.6%), V55I/A (1.2% / 8.9%, respectively), Q80K (2.1%), R155K (0.5%), and D168E (0.2%); and in HCV-1b infected patients: V36L (0.7%), T54A/S (0.2% and 0.5%, respectively), V55A (0.5%), Q80K (0.2%), D168E (1.6%), and M175L (0.5%). HCV la infected subjects had higher serum viral load than that seen in patients infected with HCV 1b. There was no difference between the proportions of NS3 RASs with regards to geographic distribution within the investigated areas. These findings should be supported by additional studies in Brazil to help in the formation of local clinical guidelines for managing hepatitis C.engrestrictedAccessgenotype 1-infected patientsexperienced patientsantiviral drugstreatment-naivehcv infectionmutationssubtypesbrazilarticleCopyright SPRINGER WIEN10.1007/s00705-018-3920-9Virology1432-8798