Detection of Salmonella DNA and drug-resistance mutation by PCR-based CRISPR-lbCas12a system

Salmonella is an important foodborne pathogen, which can cause serious public health problems. Rapid and accurate detection of Salmonella infection and drug resistance mutations in patients will provide timely guidance for clinical treatment and avoid disease progression and other related clinical problems. Here, we established a highly sensitive and quick method for Salmonella and drug resistance mutation detection based on polymerase chain reaction (PCR) and CRISPR-lbCas12a system and evaluated its practicability with clinical samples.Specific CRISPR RNAs (crRNAs) and primers are designed for Salmonella DNA and parC gene S80I mutation diagnosis. CrRNAs with and without phosphorylated modification and different crRNA preparation methods are used to assess the effect on the detection system. After optimization, we detected as low as one copy of Salmonella DNA and drug resistance mutation parC S80I with the Salmonella DNA standard. For 94 clinical samples, this method also showed high sensitivity (100%, 95% CI: 84.98-100%) and specificity (98.48%, 95% CI: 90.73-99.92%) with less time (3 h) than plate culture (16 h) and conventional antimicrobial susceptibility testing (over 16 h). Besides, one parC S80I mutant strain was detected, which is consistent with the result of DNA sequencing. Taken together, we established a highly sensitive and specific method for Salmonella infection and parC S80I drug resistance mutation detection with fewer reagents and ordinary instruments. This assay has wide application prospects for fast detection of pathogen (bacterium and virus) infection, drug resistance determination, and proper treatment guidance.

"I feel drug resistance testing allowed us to make an informed decision": qualitative insights on the role of HIV drug resistance mutation testing among children and pregnant women living with HIV in western Kenya

BACKGROUND

Pregnant women and children living with HIV in Kenya achieve viral suppression (VS) at lower rates than other adults. While many factors contribute to these low rates, the acquisition and development of HIV drug resistance mutations (DRMs) are a contributing factor. Recognizing the significance of DRMs in treatment decisions, resource-limited settings are scaling up national DRM testing programs. From provider and patient perspectives, however, optimal ways to operationalize and scale-up DRM testing in such settings remain unclear.

METHODS

Our mixed methods study evaluates the attitudes towards, facilitators to, and barriers to DRM testing approaches among children and pregnant women on antiretroviral therapy (ART) in five HIV treatment facilities in Kenya. We conducted 68 key informant interviews (KIIs) from December 2019 to December 2020 with adolescents, caregivers, pregnant women newly initiating ART or with a high viral load, and providers, laboratory/facility leadership, and policy makers. Our KII guides covered the following domains: (1) DRM testing experiences in routine care and through our intervention and (2) barriers and facilitators to routine and point-of-care DRM testing scale-up. We used inductive coding and thematic analysis to identify dominant themes with convergent and divergent subthemes.

RESULTS

The following themes emerged from our analysis: (1) DRM testing and counseling were valuable to clinical decision-making and reassuring to patients, with timely results allowing providers to change patient ART regimens faster; (2) providers and policymakers desired an amended and potentially decentralized DRM testing process that incorporates quicker sample-to-results turn-around-time, less burdensome procedures, and greater patient and provider "empowerment" to increase comfort with testing protocols; (3) facility-level delays, deriving from overworked facilities and sample tracking difficulties, were highlighted as areas for improvement.

CONCLUSIONS

DRM testing has the potential to considerably improve patient health outcomes. Key informants recognized several obstacles to implementation and desired a more simplified, time-efficient, and potentially decentralized DRM testing process that builds provider comfort and confidence with DRM testing protocols. Further investigating the implementation, endurance, and effectiveness of DRM testing training is critical to addressing the barriers and areas of improvement highlighted in our study.

TRIAL REGISTRATION

NCT03820323.

Evaluation of a novel in-house HIV-1 genotype drug resistance assay using clinical samples in China

Background

HIV drug resistance poses a major challenge for anti-retroviral treatment (ART) and the prevention and control of HIV epidemic.

Objective

The study aims to establish a novel in-house assay with high efficiency, named AP in- house method, that would be suitable for HIV-1 drug resistance detection in China.

Methods

An in-house HIV-1 genotyping method was used to sequence the partial pol gene from 60 clinical plasma samples; the results of our test were compared with a commercial ViroSeq HIV-1 genotyping system.

Results

Among sixty samples, 58(96.7%) were successfully amplified by AP in-house method, five of them harbored viral load below 1,000 copies/ml. The genotype distribution was 43.1% CRF07_BC (25/58), 39.7% CRF01_AE (23/58), 6.9% CRF55_01B (4/58), 5.2% subtype B (3/58) and 5.2% CRF08_BC (3/58). Compared with that of the ViroSeq system, the consistent rate of these nucleotides and amino acids obtained by AP in-house method was up to 99.5 ± 0.4% and 99.5 ± 0.4%, respectively. A total of 290 HIV-1 drug resistance mutations were identified by two methods, including 126 nucleoside reverse transcriptase inhibitors (NRTIs), 145 non-nucleoside reverse transcriptase inhibitors (NNRTIs) and 19 protease inhibitors (PIs) resistance mutations. Out of them, 94.1% (273/290) were completely concordant between the AP in-house method and the ViroSeq system.

Conclusion

Overall, the evaluation of AP in-house method provided comparable results to those of the ViroSeq system on diversified HIV-1 subtypes in China.

Clinical and Public Health Implications of HIV- Genetic Diversity and Drug Resistance Mutations in Angola: A Systematic Review

HIV-1 genetic diversity and drug resistance mutations (DRMs) remain a public health concern mainly in low- and middle-income countries. In this review, we estimated the HIV-1 molecular evolution over the past 40 years (1980-2019) in Angola to help guide affordable strategies for HIV-1 epidemic surveillance. We searched for studies written in English or Portuguese on HIV-1 diversity and DRMs carried out in Angola and published between 1980 and 2019. This review yielded eight studies describing a total of 493 samples. No HIV-1 Group N, O, and P were identified, whereas a ll non-B subtypes f rom Group M were identified. About 66% of HIV-1 subtypes were pure subtype and 34% recombinant strains. The frequency of recombinant strains increases from 1980 to 2019 (23.6%-41.4%, p<0.001). The subtypes C, F1, CRF02_AG, and the recombinant U/H were the most frequent. One DRM in the PIs was found (I54 M), 22 in the nucleoside reverse transcriptase inhibitors (NRTIs), and 18 in the non-nucleoside reverse transcriptase inhibitors (NNRTIs). The major DRM in the NRTIs was the M184V, whereas the G190A, K103N, and Y181C were the major DRMs in the NNRTIs. Over the past 40 years, the frequency of the DRM M184V (50-64.3%, p=0.363), G190A (17.2-46.2%, p=0.021), and K103N (34.5-42.3%, p=0.551) increased, while the frequency of Y181C (17.2-7.7%, p=0.289) decreased. The current review shows an increase in HIV-1 genetic complexity and DRMs in Angola. Our findings suggest the need to include PIs or integrase strand transfer inhibitors in the first-line antiretroviral therapy regimens in Angola.

Retrospective analysis of HIV-1 drug resistance mutations in Suzhou, China from 2009 to 2014

In this study, we investigated drug resistance levels in human immunodeficiency virus (HIV)-1-infected patients in Suzhou by retrospectively analyzing this property and the characteristics of circulating HIV-1 strains collected from 2009 to 2014. A total of 261 HIV-1-positive plasma samples, confirmed by the Suzhou CDC, were collected and evaluated to detect HIV-1 drug resistance genotypes using an in-house method. The pol gene fragment was amplified, and its nucleic acid sequence was determined by Sanger sequencing. Drug resistance mutations were then analyzed using the Stanford University HIV resistance database ( https://hivdb.stanford.edu ). A total of 216 pol gene fragments were amplified and sequenced with 16.7% (36/216) of sequences revealing these mutations. The drug resistance rates of protease, nucleoside reverse transcriptase, and non-nucleoside reverse transcriptase inhibitors (NNRTIs) were 4/36 (11.1%), 2/36 (5.6%), and 30/36 (83.3%), respectively. Five surveillance drug resistance mutations were found in 36 sequences, of which, three were found among specimens of men who have sex with men. Potential low-level resistance accounted for 33% of amino acid mutations associated with NNRTIs. Two of the mutations, M230L and L100I, which confer a high level of resistance efavirenz (EFV) and nevirapine (NVP) used as NNRTIs for first-line antiretroviral therapy (ART), were detected in this study. Therefore, when HIV-1 patients in Suzhou are administered fist-line ART, much attention should be paid to the status of these mutations that cause resistance to EVP, EFV, and NVP.

Highly sensitive and specific detection of hepatitis B virus DNA and drug resistance mutations utilizing the PCR-based CRISPR-Cas13a system

OBJECTIVES

Undetectable or low-level hepatitis B virus (HBV) DNA and drug resistance mutations in patients may increase the risk of HBV transmission or cause active viral replication and other clinical problems. Here, we established a highly sensitive and practical method for HBV and drug resistance detection using a polymerase chain reaction (PCR) -based CRISPR-Cas13a detection system (referred to as PCR-CRISPR) and evaluated its detection capability using clinical samples.

METHODS

Specific CRISPR RNAs (crRNAs) are designed for HBV DNA detection and YMDD (tyrosine-methionine-aspartate-aspartate) variant identification. The HBV DNA was detected in 312 serum samples for HBV diagnosis using quantification PCR (qPCR) and PCR-CRISPR. Additionally, 424 serum samples for YMDD testing were detected by qPCR, direct sequencing, and our assay.

RESULTS

Using PCR-CRISPR, one copy per test of HBV DNA was detected with HBV-1 crRNA in 15 min after PCR amplification. Consistent results with qPCR were observed for 302 samples, while the remaining 10 samples with low-level HBV DNA were detectable by PCR-CRISPR and droplet digital PCR but not by qPCR. PCR-CRISPR diagnosed all 412 drug-resistant samples detected by the YMDD detection qPCR kit and direct sequencing, as well as the other 12 drug-resistant samples with low-level HBV DNA undetectable by qPCR and direct sequencing.

CONCLUSIONS

We developed a novel PCR-CRISPR method for highly sensitive and specific detection of HBV DNA and drug resistance mutations. One copy per test for HBV DNA and YMDD drug resistance mutations could be detected. This method has wide application prospects for the early detection of HBV infection, drug resistance monitoring and treatment guidance.

Natural polymorphisms in HIV-1 CRF01_AE strain and profile of acquired drug resistance mutations in a long-term combination treatment cohort in northeastern China

BACKGROUND

The impacts of genetic polymorphisms on drug resistance mutations (DRMs) among various HIV-1 subtypes have long been debated. In this study, we aimed to analyze the natural polymorphisms and acquired DRM profile in HIV-1 CRF01_AE-infected patients in a large first-line antiretroviral therapy (ART) cohort in northeastern China.

METHODS

The natural polymorphisms of CRF01_AE were analyzed in 2034 patients from a long-term ART cohort in northeastern China. The polymorphisms in 105 treatment failure (TF) patients were compared with those in 1148 treatment success (TS) patients. The acquired DRM profile of 42 patients who experienced TF with tenofovir/lamivudine/efavirenz (TDF/3TC/EFV) treatment was analyzed by comparing the mutations at TF time point to those at baseline. The Stanford HIVdb algorithm was used to interpret the DRMs. Binomial distribution, McNemar test, Wilcoxon test and CorMut package were used to analyze the mutation rates and co-variation. Deep sequencing was used to analyze the evolutionary dynamics of co-variation.

RESULTS

Before ART, there were significantly more natural polymorphisms of 31 sites on reverse transcriptase (RT) in CRF01_AE than subtype B HIV-1 (|Z value| ≥ 3), including five known drug resistance-associated sites (238, 118, 179, 103, and 40). However, only the polymorphism at site 75 was associated with TF (|Z value| ≥ 3). The mutation rate at 14 sites increased significantly at TF time point compared to baseline, with the most common DRMs comprising G190S/C, K65R, K101E/N/Q, M184 V/I, and V179D/I/A/T/E, ranging from 66.7 to 45.2%. Moreover, two unknown mutations (V75 L and L228R) increased by 19.0 and 11.9% respectively, and they were under positive selection (Ka/Ks > 1, log odds ratio [LOD] > 2) and were associated with several other DRMs (cKa/Ks > 1, LOD > 2). Deep sequencing of longitudinal plasma samples showed that L228R occurred simultaneously or followed the appearance of Y181C.

CONCLUSION

The high levels of natural polymorphisms in CRF01_AE had little impact on treatment outcomes. The findings regarding potential new CRF01_AE-specific minor DRMs indicate the need for more studies on the drug resistance phenotype of CRF01_AE.

Low levels of HIV-1 drug resistance mutations in patients who achieved viral re-suppression without regimen switch: a retrospective study

BACKGROUND

We identified a HIV-positive cohort in virologic failure (VF) who re-suppressed without drug switch. We characterized their drug resistance mutations (DRM) and adherence profiles to learn how to better manage HIV drug resistance. A retrospective cohort study utilizing clinical data and stored samples. Patients received ART at three Nigerian treatment centres. Plasma samples stored when they were in VF were genotyped.

RESULT

Of 126 patients with samples available, 57 were successfully genotyped. From ART initiation, the proportion of patients with adherence ≥90% increased steadily from 54% at first high viral load (VL) to 67% at confirmed VF, and 81% at time of re-suppressed VL. Sixteen (28%) patients had at least one DRM. Forty-six (81%) patients had full susceptibility to the three drugs in their first-line (1 L) regimen. Thirteen (23%) were resistant to at least one antiretroviral drug but three were resistant to drugs not used in Nigeria. Ten patients had resistance to their 1 L drug(s) and six were fully susceptible to the three drugs in the recommended second-line regimen.

CONCLUSION

This cohort had little drug resistance mutations. We conclude that if adherence is not assured, patients could exhibit virologic failure without having developed mutations associated with drug resistance.

Trend of HIV-1 drug resistance in China: A systematic review and meta-analysis of data accumulated over 17 years (2001-2017)

BACKGROUND

The emergence and spread of HIV-1 drug resistance may compromise HIV control globally. In response to HIV/AIDS epidemic, China launched national HIV/AIDS treatment program in 2003, and started to accumulate drug resistance data since 2001. In this study we aimed to assess the level, trend and distribution of HIV-1 drug resistance during a period of 17 years from 2001 to 2017, and to characterize crucial drug resistance mutations.

METHODS

We systematically reviewed 4737 studies published between January 1, 2001 and March 31, 2019 in PubMed, Embase, China National Knowledge Infrastructure (CNKI), WanFang Database, Web of Science, conference abstracts from the Chinese Medical Association and the Chinese AIDS Academic Conferences, and selected 170 studies that met our study criteria. To assess the prevalence of drug resistance in whole country or a local region, we performed pooled analyses of raw data. The transformed proportions were pooled using the inverse variance fixed effects methods or the DerSimonian-Laired random effects methods. The temporal trend of transmitted drug resistance (TDR) was determined using generalized additive model implemented in the Mgcv version 1.8 package. HIV-1 genotypic resistance was analyzed using the Stanford HIVdb algorithm.

FINDINGS

We assembled 218 datasets from 170 selected studies (129 in Chinese and 41 in English), covering 21,451 ART-naïve and 30,475 ART-treated individuals with HIV-1 infection. The pooled prevalence of TDR was 3.0% (95%CI: 2.8-3.2), including 0.7% (95%CI: 0.4-1.0), 1.4% (95%CI: 1.3-1.6) and 0.5% (95%CI: 0.4-0.6) for nucleoside reverse transcriptase inhibitor (NRTI), non-NRTI (NNRTI) and protease inhibitor (PI) resistance, respectively. The acquired drug resistance (ADR) prevalence was 44.7% (95%CI: 39.3-50.2), including 31.4% (95%CI: 28.2-34.6), 39.5% (95%CI: 35.6-43.5) and 1.0% (95%CI: 0.8-1.2) for NRTI, NNRTI and PI resistance, respectively. TDR and ADR prevalence had characteristic regional patterns. The worst prevalence of drug resistance occurred in Central China, and higher ADR prevalence occurred in South China than North China. TDR in whole country has risen since 2012, and this rise was driven mainly by NNRTI resistance. One NRTI-associated (M184V/I) and three NNRTI-associated (K103N/S, Y181C/I and G190A/S) mutations had high percentages in ART-naïve and ART-treated individuals, and these mutations conferred high-level resistance to 3TC, EFV and/or NVP.

INTERPRETATION

These findings suggest that the current available first-line ART regimens containing 3TC and/or EFV or NVP need to be revised. In addition, scale-up of multiple viral load measurements per year and drug resistance testing prior to ART initiation are recommended. Furthermore, implementation of pre-treatment education and counseling to improve patient adherence to ART is encouraged.

FUNDING

This work was supported by grants from the National Natural Science Foundation of China (81672033, U1302224, and 81271888) and Open Research Fund Program of the State Key Laboratory of Virology of China (2019IOV002).

Transmitted drug resistance mutations and trends of HIV-1 subtypes in treatment-naïve patients: A single-centre experience

OBJECTIVES

Transmitted drug resistance (TDR) and HIV-1 genetic diversity may affect treatment efficacy and clinical outcomes. Here we describe the circulating viral subtypes and estimate the prevalence of drug resistance among antiretroviral therapy (ART)-naïve patients attending Sapienza University Hospital (Rome, Italy) from 2006-2017.

METHODS

Genotypic resistance testing (GRT) was performed on 668 ART-naïve patients for integrase (n = 52), protease and reverse transcriptase (n = 668) sequences.

RESULTS

Twenty-one different HIV-1 subtypes and circulating recombinant forms (CRFs) were identified. Subtype B was the most common (67.1%), followed by CRF02_AG (8.4%), and subtypes C and F (both 6.0%). A significantly increase in the proportion of non-B strains (P < 0.001) and the rate of non-Italian patients was observed over time. The overall prevalence of TDR was 9.4% (NRTI, 4.2%; NNRTI, 5.8%; and PI, 1.0%) and was higher in subtype B strains. Transmitted INSTI mutations (Q148H and G140S) responsible for high-level resistance to raltegravir and elvitegravir and intermediate resistance to dolutegravir and bictegravir were found, for the first time, in two individuals. Minor or accessory INSTI mutations were detected in 17.3% of patients. No significant decrease in the prevalence of TDR was documented over time.

CONCLUSION

The significant increase in non-B subtypes suggests that the molecular epidemiology of HIV-1 is changing. Detection of a major INSTI mutation in two ART-naïve patients highlights the importance of performing GRT before commencing treatment. This finding and the lack of a significant reduction in TDRs underline the importance of continuous surveillance of resistance mutations.

[Drug resistance mutations and its associated factors among 579 HIV/AIDS patients experiencing failure of antiretroviral therapy in Jiangsu Province, China]

Objective: To understand the incidence and related factors of HIV-1 drug resistance among HIV/AIDS patients experiencing treatment failure in Jiangsu province, China. Methods: The HIV/AIDS integrated prevention and control data information management system of China were used to collect the basic data of patients, blood specimens were collected from patients who had antiretroviral therapy (ART) failure with ≥12 months and older than 18 years in 2016 in Jiangsu, excluding cases with missing information, 713 cases were enrolled in this study. HIV-1 RNA was extracted, and then pol gene region was amplified and sequenced. The obtain sequences were submitted to Stanford University HIV Drug Resistance Database to interpret and analyse HIV-1 drug resistance and sub-types. Multivariate logistic regression model was used to explore the related factors of drug resistance. Results: A total of 579 subjects were amplified successfully, male accounted for 85.66% (496 cases), and the median age was 39 years old. The main route of infection was sexual transmission (553 cases, 95.51%). A total of 331 patients with drug resistance gene mutation were detected, drug resistance mutation rate was 57.18%. Compared with patients with baseline CD4(+)T cell count >500 cells/μl, patients with CD4(+)T cell count in 201-500 cells/mm(3) and ≤200 cells/μl had a higher incidence of genetic drug resistance, the odds ratio was 3.33 and 6.87, respectively. Compared with patients with treatment less than 24 months, patients treated for 25-48 months had a higher incidence of drug resistance, the odds ratio was 1.88. Compared with patients infected by CRF07_BC strains, patients infected by CRF01_AE strains were associated with higher incidence of drug resistance, the odds ratio was 2.22 and 3.32, respectively. Protease inhibitor (PI) resistance mutations, nucleoside reverse transcriptase inhibitor (NRTI) and non-nucleoside reverse transcriptase inhibitor (NNRTI) were found in 3.80%, 33.16% and 53.37% of patients, respectively. 31.95% of patients harbored NRTI and NNRTI resistance mutations simultaneously. M184V/I and K103N/Q were the highest frequency of NRTI and NNRTI resistance mutation, the prevalence of M184V/I and K103N/Q were 28.15% and 22.28%, respectively. Conclusion: The status of HIV-1 drug resistance mutations are complex and diverse among patients experiencing failure of ART in Jiangsu. Patients with lower baseline CD4(+)T cell count, longer treatment time and HIV-1 CRF01_AE and B strains infection were associated with higher incidence of drug resistance mutation.

Neuraminidase Gene Variations in Influenza A(H1N1)pdm09 Virus among Patients Admitted to Refferal Pulmonary Hospital, Tehran, Iran in 2009-2013

BACKGROUND

Neuraminidase (NA) is one of the surface proteins of influenza A virus, which plays an important role in immunization against influenza infection and is recognized as an important therapeutic target. Genetic and antigenic changes and substitutions can influence the efficacy of vaccine and change viral sensitivity to NA inhibitors (NAIs). In this study, we performed phylogenetic and molecular analyses of NA changes in influenza A(H1N1)pdm09 virus, compared them with the corresponding vaccine strain, and examined drug resistance mutations in isolates from patients.

MATERIALS AND METHODS

The complete sequence of NA genes from 34 pandemic H1N1 isolates (identified in 2009-2010, 2010-2011, and 2013) was determined and analyzed both genetically and antigenically. The phylogenetic tree was plotted relative to the corresponding vaccine strain, using MEGA6 software package, based on the maximum likelihood method and JTT matrix (bootstrap value of 1000).

RESULTS

The phylogenetic analysis of pandemic isolates showed 31 amino acid substitutions in NA genes, compared to the vaccine strain. Some of these substitutions (N248D, V241I, N369K, N44S, and N200S) were important in terms of phylogenetic relationship, while the rest (D103N, V106I, R130T, N200S, G201E, and G414R) influenced the antigenic indices of B-cell epitopes. The catalytic sites, framework sites, and N-glycosylation remained unchanged in the studied samples. Meanwhile, H275Y substitution, related to oseltamivir resistance, was detected in 3 isolates. The average nucleotide identity of NAs with the corresponding vaccine strain was 99.415%, 98.607%, and 98.075% in 2009-2010, 2010-2011, and 2012-2013, respectively.

CONCLUSION

In this study, we provided basic information on the genetic and antigenic changes of NA genes in influenza A(H1N1)pdm09 virus from patients in 3 different seasons in Tehran, Iran. Considering the viral NAI resistance and changes in NA gene sequences of the isolates in comparison with the vaccine strain, further studies should be performed to monitor genetic changes in Iran. Moreover, the efficacy of vaccines should be examined.

Next generation sequencing of the hepatitis C virus NS5B gene reveals potential novel S282 drug resistance mutations

Identifying HCV drug resistance mutations (DRMs) is increasingly important as new direct acting antiviral therapies (DAA) become available. Tagged pooled pyrosequencing (TPP) was originally developed as cost-effective approach for detecting low abundance HIV DRMs. Using 127 HCV-positive samples from a Canadian injection drug user cohort, we demonstrated the suitability and efficiency of TPP for evaluating DRMs in HCV NS5B gene. At a mutation identification threshold of 1%, no nucleoside inhibitor DRMs were detected among these DAA naïve subjects. Clinical NS5B resistance to non-nucleoside inhibitors and interferon/ribavirin was predicted to be low within this cohort. S282T mutation, the primary mutation selected by sofosbuvir in vitro, was not identified while S282G/C/R variants were detected in 9 subjects. Further characterization on these new S282 variants using in silico molecular modeling implied their potential association with resistance. Combining TPP with in silico analysis detects NS5B polymorphisms that may explain differences in treatment outcomes.

A case of successful treatment with telaprevir-based triple therapy for hepatitis C infection after treatment failure with vaniprevir-based triple therapy

Recently direct-acting antiviral agents, such as hepatitis C virus (HCV) non-structural 3/4A (NS3/4A) protease inhibitors (PI), have been introduced, and triple therapy regimens that include PI with conventional pegylated interferon α and ribavirin have significantly improved the sustained virological response (SVR) rate, up to 80% for both treatment-naïve and treatment-experienced patients with HCV genotype 1. We here report for the first time a case of the successful treatment of HCV genotype 1 infection with a first generation PI drug (telaprevir) based triple therapy after treatment failure with a second generation PI drug (vaniprevir) based triple therapy. A 67-year-old treatment-naïve Japanese man with HCV genotype 1b infection took part in a phase III clinical trial of vaniprevir-based triple therapy. His serum HCV RNA had become undetectable at week 2 and SVR was highly expected, but HCV RNA reappeared at week 4 after vaniprevir treatment. Polymerase chain reaction direct sequence of the HCV NS3/4A gene at week 8 after vaniprevir treatment showed the emergence of a vaniprevir-resistance mutation (D168V), the probable reason for the treatment failure. Six months later, retreatment with telaprevir-based triple therapy was started. Although the dosages of telaprevir and ribavirin had to be reduced due to severe anemia, the patient achieved an SVR. This case shows the value of repeating PI-based triple therapy with a different drug, a process that would reduce the chance of drug resistant mutation.