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Abstract Background The challenges in culturing Treponema pallidum have hindered molecular-biological analysis. This study aims to establish a molecular epidemiological analysis of syphilis among Japanese men who have sex with men (MSM) and to investigate the relationship between bacteremia and associated pathophysiology. Methods We used whole blood specimens from syphilis-diagnosed individuals in Tokyo, collected between February 2019 and June 2022. All individuals were MSM, and most were people with HIV (97.2%). We used a multi-locus sequence typing (MLST) scheme for epidemiological analysis. Sequences for MLST (TP0136, TP0548, and TP0705) were obtained. Results Out of 71 whole blood samples, 26 samples (36.6%) were positive for TP0136, and we sequenced three loci for MLST in 22 samples (31.0%). The most frequently detected sequence type (ST) was ST3 (n = 9), followed by ST6 (n = 6). Phylogenetic analysis revealed that 12 samples belonged to the SS14-like group (60%), and 8 samples belonged to the Nichols-like group (40%). Treponema pallidum subsp. endemicum (TEN), the cause of bejel was detected in three samples (12%). There was a significant association between TP0136 detection rate and C- reactive protein (CRP) (77.0% at a cut-off:0.5 mg/dL). Conclusion Both SS14-like and Nichols-like strains were circulating concurrently, and TEN could have been sexually transmitted among MSM with HIV. Elevated CRP may indicate the presence of the pathogen in the blood.

A patient in Japan with HIV began antiretroviral therapy because of acute hepatitis B virus (HBV) 15 years ago, with low hepatitis B surface antibody, and experienced breakthrough HBV reactivation 4 months after switching from bictegravir/emtricitabine/tenofovir alafenamide to cabotegravir/rilpivirine. An immune escape mutation, E164V, was identified in the isolated HBV DNA.

IntroductionPlasminogen activator inhibitor-1 (PAI-1) is linked to thrombosis and endothelial dysfunction in severe COVID-19. The +43 G>A PAI-1 and 4G/5G promoter polymorphism can influence PAI-1 expression. The 4G5G PAI-1 promoter gene polymorphism constitutes the 4G4G, 4G5G, and 5G5G genotypes. However, the impact of PAI-1 polymorphisms on disease severity or endothelial dysfunction remains unclear.MethodsClinical data, sera, and peripheral blood mononuclear cells (PBMCs) of COVID-19 patients were studied.ResultsComorbidities and clinical biomarkers did not correlate with genotypes in either polymorphism. However, differences between fibrinolytic factors and interleukin-1β (IL-1β) were identified in genotypes of the 4G/5G but not the 43 G>A PAI polymorphism. Patients with the 4G4G genotype of the 4G/5G polymorphism showed high circulating PAI-1, mainly complexed with plasminogen activators, and low IL-1β and plasmin levels, indicating suppressed fibrinolysis. NFκB was upregulated in PBMCs of COVID-19 patients with the 4G4G genotype.DiscussionMechanistically, IL-1β enhanced PAI-1 expression in 4G4G endothelial cells, preventing the generation of plasmin and cleavage products like angiostatin, soluble uPAR, and VCAM1. We identified inflammation-induced endothelial dysfunction coupled with fibrinolytic system overactivation as a risk factor for patients with the 5G5G genotype.

Abstract Background People living with HIV (PLWH) with chronic inflammation may have an increasing risk for coronavirus disease 2019 (COVID-19) severity; however, the impact of their gut microbiota on COVID-19 is not fully elucidated. Here, we analyzed the temporal changes in the gut microbiota composition of hospitalized severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected PLWH (PLWH-CoV) and their correlation with COVID-19 severity. Result The 16S rRNA analysis results using stool samples (along the timeline from disease onset) from 12 hospitalized PLWH-CoV, whose median CD4 + T cell count was 671 cells/µl, were compared to those of 19 healthy people and 25 PLWH. Bacterial diversity in PLWH-CoV is not significantly different from that of healthy people and SARS-CoV-2 non-infected PLWH, but a significant difference in the microbiota diversity was observed in the classification according to the disease severity. Immediately after the disease onset, remarkable changes were observed in the gut microbiota of PLWH-CoV, and the changing with a decrease in some short-chain fatty acid-producing bacteria and an increase in colitis-related pathobiont. In the second week after disease onset, relative amounts of specific bacteria distinguished between disease severity. One month after the disease onset, dysbiosis of the gut microbiota persisted, and the number of Enterobacteriaceae, mainly Escherichia-Shigella, which is potentially pathogenic, increased and were enriched in patients who developed post-acute sequelae of COVID-19 (PASC). Conclusion The changes in the gut microbiota associated with SARS-CoV-2 infection observed in PLWH in this study indicated a persistent decrease in SCFA-producing bacteria and an intestinal environment with an increase in opportunistic pathogens associated with enteritis. This report demonstrates that the intestinal environment in PLWH tends to show delayed improvement even after COVID-19 recovery, and highlights the importance of the dysbiosis associated with SARS-CoV-2 infection as a potential factor in the COVID-19 severity and the PASC in PLWH.

Abstract We assessed whether the impact of cabotegravir plus rilpivirine on inflammation reduction differs from that of oral antiretrovirals, using real-world data. Inflammatory biomarkers and lipid profiles were followed from baseline to 8 months after switching. Seventy-eight participants were analyzed. The CD4/CD8 ratio and C-reactive protein did not change. There were transient decreases in CD8 and CD4 counts in the group that switched from the dolutegravir-based regimen, but not in the tenofovir alafenamide-based regimen group. High-density lipoprotein (HDL) cholesterol increased, resulting in a decrease in the total-cholesterol to HDL cholesterol ratio, whereas there was no significant change in low-density lipoprotein cholesterol.

Summary: The emergence and spread of new SARS-CoV-2 variants with mutations in the spike protein, such as the XBB.1.5 and XBB.1.9.1 sublineages, raise concerns about the efficacy of current COVID-19 vaccines and therapeutic monoclonal antibodies (mAbs). In this study, none of the mAbs we tested neutralized XBB.1.9.1 or XBB.1.5, even at the highest concentration used. We also found that the bivalent mRNA vaccine could enhance humoral immunity against XBB.1.9.1, but that XBB.1.9.1 and XBB.1.5 still evaded humoral immunity induced by vaccination or infection. Moreover, the susceptibility of XBB.1.9.1 to remdesivir, molnupiravir, nirmatrelvir, and ensitrelvir was similar to that of the ancestral strain and the XBB.1.5 isolate in vitro. Finally, we found the replicative fitness of XBB.1.9.1 to be similar to that of XBB.1.5 in hamsters. Our results suggest that XBB.1.9.1 and XBB.1.5 have similar antigenicity and replicative ability, and that the currently available COVID-19 antivirals remain effective against XBB.1.9.1.

Summary: SARS-CoV-2 has gradually acquired amino acid substitutions in its S protein that reduce the potency of neutralizing antibodies, leading to decreased vaccine efficacy. Here, we attempted to obtain mutant viruses by passaging SARS-CoV-2 in the presence of plasma samples from convalescent patients or vaccinees to determine which amino acid substitutions affect the antigenicity of SARS-CoV-2. Several amino acid substitutions in the S2 region, as well as the N-terminal domain (NTD) and receptor-binding domain (RBD), affected the neutralization potency of plasma samples collected from vaccinees, indicating that amino acid substitutions in the S2 region as well as those in the NTD and RBD affect neutralization by vaccine-induced antibodies. Furthermore, the neutralizing potency of vaccinee plasma samples against mutant viruses we obtained or circulating viruses differed among individuals. These findings suggest that genetic backgrounds of vaccinees influence the recognition of neutralizing epitopes.

Abstract Background Hepatitis C virus (HCV) has been mainly transmitted through injection drug use, but recently, sexual transmission among men who have sex with men (MSM), which is also a major route of HIV transmission, is increasing. However, the prevalence of HIV and the incidence of other sexually transmitted infections (STIs) among HCV patients have been rarely reported. Methods Using a healthcare insurance claim data of employees and their dependents covering seven-million people in Japan, we evaluated HIV prevalence among HCV patients aged 20–59 years. Hemophilia patients were excluded. HIV and HCV were defined by registered diagnoses and receiving viral RNA testing. The time course of HCV and HIV infections was analyzed. Incidences of syphilis, amebiasis, chlamydia, gonorrhea, hepatitis A, and hepatitis B were assessed. Results From April 2012 to August 2018, 6,422 HCV patients were identified. HIV prevalence was 0.48% (31/6422, 95% CI [confidence interval]: 0.33–0.68%). HIV was diagnosed after HCV in 3.2% (1/31), before HCV in 58.1% (18/31), and concurrently in 38.7% (12/31). Compared with HCV patients without HIV infection, HCV/HIV co-infected patients were younger (median age, 37 vs 51 years, p

Abstract Background Percutaneous transhepatic gallbladder drainage (PTGBD) is recommended for acute cholecystitis patients at high risk for surgical treatment. However, there is no evidence about the best timing of surgery after PTGBD. Here, we retrospectively investigated the influence of the interval between PTGBD and surgery on perioperative outcomes and examined the optimal timing of surgery after PTGBD. Methods We performed a retrospective analysis of 22 patients who underwent cholecystectomy after PTGBD from January 2008 to August 2019. We examined perioperative factors between patients with an interval of ≤ 7 days between PTGBD and cholecystectomy (≤ 7-day group; n = 12) and those with an interval of ≥ 8 days (≥ 8-day group; n = 10). Moreover, we also examined perioperative factors between patients with an interval of ≤ 14 days from PTGBD to cholecystectomy (≤ 14-day group; n = 10) and those with an interval of ≥ 15 days (≥ 15-day group; n = 12). Results Of the 22 patients, 9 had Grade I cholecystitis, 12 had Grade II cholecystitis, and 2 had Grade III cholecystitis. Nine patients had high-grade cholecystitis before PTGBD and 13 had a poor general condition. We examined perioperative factors between patients with an interval of ≤ 7 days between PTGBD and cholecystectomy (≤ 7-day group; n = 12) and those with an interval of ≥ 8 days (≥ 8-day group; n = 10). The C-reactive protein (CRP) level before surgery was significantly higher (12.70 ± 1.95 mg/dL vs. 1.13 ± 2.13 mg/dL, p = 0.0007) and the total hospitalization was shorter (17.6 ± 8.0 days vs. 54.1 ± 8.8 days, p = 0.0060) in the ≤ 7-day group than in the ≥ 8-day group. We also examined perioperative factors between patients with an interval of ≤ 14 days from PTGBD to cholecystectomy (≤ 14-day group; n = 14) and those with an interval of ≥ 15 days (≥ 15-day group; n = 8). The CRP level before surgery was significantly higher (11.13 ± 2.00 mg/dL vs. 0.99 ± 2.64 mg/dL, p = 0.0062) and the total hospitalization was shorter (19.5 ± 7.2 days vs. 59.9 ± 9.5 days, p = 0.0029) in the ≤ 14-day group than in the ≥ 15-day group. However, there were no significant differences between the ≤ 14-day group and the ≥ 15-day group in the levels of hepatic enzymes before surgery, adhesion grade, amount of bleeding during surgery, operative duration, frequency of surgical complications, or length of hospitalization after surgery. Conclusions The interval between PTGBD and surgery has little influence on perioperative outcomes.

ABSTRACT The role of the intestinal microbiota in coronavirus disease 2019 (COVID-19) is being elucidated. Here, we analyzed the temporal changes in microbiota composition and the correlation between inflammation biomarkers/cytokines and microbiota in hospitalized COVID-19 patients. We obtained stool specimens, blood samples, and patient records from 22 hospitalized COVID-19 patients and performed 16S rRNA metagenomic analysis of stool samples over the course of disease onset compared to 40 healthy individual stool samples. We analyzed the correlation between the changes in the gut microbiota and plasma proinflammatory cytokine levels. Immediately after admission, differences in the gut microbiota were observed between COVID-19 patients and healthy subjects, mainly including enrichment of the classes Bacilli and Coriobacteriia and decrease in abundance of the class Clostridia. The bacterial profile continued to change throughout the hospitalization, with a decrease in short-chain fatty acid-producing bacteria including Faecalibacterium and an increase in the facultatively anaerobic bacteria Escherichia-Shigella. A consistent increase in Eggerthella belonging to the class Coriobacteriia was observed. The abundance of the class Clostridia was inversely correlated with interferon-γ level and that of the phylum Actinobacteria, which was enriched in COVID-19, and was positively correlated with gp130/sIL-6Rb levels. Dysbiosis was continued even after 21 days from onset. The intestines tended to be an aerobic environment in hospitalized COVID-19 patients. Because the composition of the gut microbiota correlates with the levels of proinflammatory cytokines, this finding emphasizes the need to understand how pathology is related to the temporal changes in the specific gut microbiota observed in COVID-19 patients. IMPORTANCE There is growing evidence that the commensal microbiota of the gastrointestinal and respiratory tracts regulates local and systemic inflammation (gut-lung axis). COVID-19 is primarily a respiratory disease, but the involvement of microbiota changes in the pathogenesis of this disease remains unclear. The composition of the gut microbiota of patients with COVID-19 changed over time during hospitalization, and the intestines tended to be an aerobic environment in hospitalized COVID-19 patients. These changes in gut microbiota may induce increased intestinal permeability, called leaky gut, allowing bacteria and toxins to enter the circulatory system and further aggravate the systemic inflammatory response. Since gut microbiota composition correlates with levels of proinflammatory cytokines, this finding highlights the need to understand how pathology relates to the gut environment, including the temporal changes in specific gut microbiota observed in COVID-19 patients.

The influenza A(H1N1)pdm09 virus that emerged in 2009 causes seasonal epidemic worldwide. The virus acquired several amino acid substitutions that were responsible for antigenic drift until the 2018–2019 influenza season. Viruses possessing mutations in the NA and PA proteins that cause reduced susceptibility to NA inhibitors and baloxavir marboxil, respectively, have been detected after antiviral treatment, albeit infrequently. Here, we analyzed HA, NA, and PA sequences derived from A(H1N1)pdm09 viruses that were isolated during the 2018–2019 and 2019–2020 influenza seasons in Japan. We found that A(H1N1)pdm09 viruses possessing the D187A and Q189E substitutions in HA emerged and dominated during the 2019–2020 season; these substitutions in the antigenic site Sb, a high potency neutralizing antibody-eliciting site for humans, changed the antigenicity of A(H1N1)pdm09 viruses. Furthermore, we found that isolates possessing the N156K substitution, which was predicted to affect the antigenicity of A(H1N1)pdm09 virus at the laboratory level, were detected at a frequency of 1.0% in the 2018–2019 season but 10.1% in the 2019–2020 season. These findings indicate that two kinds of antigenically drifted viruses—N156K and D187A/Q189E viruses—co-circulated during the 2019–2020 influenza season in Japan.

Although there is strong evidence that SARS-CoV-2 infection is associated with adverse outcomes in certain ethnic groups, the association of disease severity and risk factors such as comorbidities and biomarkers with racial disparities remains undefined. This retrospective study between March 2020 and February 2021 explores COVID-19 risk factors as predictors for patients’ disease progression through country comparison. Disease severity predictors in Germany and Japan were cardiovascular-associated comorbidities, dementia, and age. We adjusted age, sex, body mass index, and history of cardiovascular disease comorbidity in the country cohorts using a propensity score matching (PSM) technique to reduce the influence of differences in sample size and the surprisingly young, lean Japanese cohort. Analysis of the 170 PSM pairs confirmed that 65.29% of German and 85.29% of Japanese patients were in the uncomplicated phase. More German than Japanese patients were admitted in the complicated and critical phase. Ethnic differences were identified in patients without cardiovascular comorbidities. Japanese patients in the uncomplicated phase presented a suppressed inflammatory response and coagulopathy with hypocoagulation. In contrast, German patients exhibited a hyperactive inflammatory response and coagulopathy with hypercoagulation. These differences were less pronounced in patients in the complicated phase or with cardiovascular diseases. Coagulation/fibrinolysis-associated biomarkers rather than inflammatory-related biomarkers predicted disease severity in patients with cardiovascular comorbidities: platelet counts were associated with severe illness in German patients. In contrast, high D-dimer and fibrinogen levels predicted disease severity in Japanese patients. Our comparative study indicates that ethnicity influences COVID-19-associated biomarker expression linked to the inflammatory and coagulation (thrombo-inflammatory) response. Future studies will be necessary to determine whether these differences contributed to the less severe disease progression observed in Japanese COVID-19 patients compared with those in Germany.

ABSTRACT Chronic inflammation is a hallmark of human immunodeficiency virus (HIV) infection and a risk factor for the development and progression of age-related comorbidities. Although HIV-associated gut dysbiosis has been suggested to be involved in sustained chronic inflammation, there remains a limited understanding of the association between gut dysbiosis and chronic inflammation during HIV infection. Here, we investigated compositional changes in the gut microbiome and its role in chronic inflammation in patients infected with HIV. We observed that the gut microbiomes of patients with low CD4 counts had reduced alpha diversity compared to those in uninfected controls. Following CD4 recovery, alpha diversity was restored, but intergroup dissimilarity of bacterial composition remained unchanged between patients and uninfected controls. Patients with HIV had higher abundance of the classes Negativicutes, Bacilli, and Coriobacteriia, as well as depletion of the class Clostridia. These relative abundances positively correlated with inflammatory cytokines and negatively correlated with anti-inflammatory cytokines. We found that gut dysbiosis accompanying HIV infection was characterized by a depletion of obligate anaerobic Clostridia and enrichment of facultative anaerobic bacteria, reflecting increased intestinal oxygen levels and intestinal permeability. Furthermore, it is likely that HIV-associated dysbiosis shifts the immunological balance toward inflammatory Th1 responses and encourages proinflammatory cytokine production. Our results suggest that gut dysbiosis contributes to sustaining chronic inflammation in patients with HIV infection despite effective antiretroviral therapy and that correcting gut dysbiosis will be effective in improving long-term outcomes in patients. IMPORTANCE Chronic inflammation is a hallmark of HIV infection and is associated with the development and progression of age-related comorbidities. Although the gastrointestinal tract is a major site of HIV replication and CD4+ T-cell depletion, the role of HIV-associated imbalance of gut microbiome in chronic inflammation is unclear. Here, we aimed to understand the causal relationship between abnormalities in the gut microbiome and chronic inflammation in patients with HIV. Our results suggest HIV-associated gut dysbiosis presents a more aerobic environment than that of healthy individuals, despite prolonged viral suppression. This dysbiosis likely results from a sustained increase in intestinal permeability, which supports sustained bacterial translocation in HIV patients, despite effective therapy. Additionally, we observed that several bacterial taxa enriched in HIV patients were associated with increased expression of inflammatory cytokines. Collectively, these results suggest that gut dysbiosis plays an important role in chronic inflammation in HIV patients.

Coronavirus disease is reported to affect the cardiovascular system. We showed that relative bradycardia was a common characteristic for 54 patients with PCR-confirmed mild-to-moderate coronavirus disease in Japan. This clinical sign could help clinicians to diagnose this disease.

Background: To develop an effective vaccine against a novel viral pathogen, it is important to understand the longitudinal antibody responses against its first infection. Here we performed a longitudinal study of antibody responses against SARS-CoV-2 in symptomatic patients. Methods: Sequential blood samples were collected from 39 individuals at various timepoints between 0 and 154 days after onset. IgG or IgM titers to the receptor binding domain (RBD) of the S protein, the ectodomain of the S protein, and the N protein were determined by using an ELISA. Neutralizing antibody titers were measured by using a plaque reduction assay. Findings: The IgG titers to the RBD of the S protein, the ectodomain of the S protein, and the N protein peaked at about 20 days after onset, gradually decreased thereafter, and were maintained for several months after onset. Extrapolation modeling analysis suggested that the IgG antibodies were maintained for this amount of time because the rate of reduction slowed after 30 days post-onset. IgM titers to the RBD decreased rapidly and disappeared in some individuals after 90 days post-onset. All patients, except one, possessed neutralizing antibodies against authentic SARS-CoV-2, which they retained at 90 days after onset. The highest antibody titers in patients with severe infections were higher than those in patients with mild or moderate infections, but the decrease in antibody titer in the severe infection cohort was more remarkable than that in the mild or moderate infection cohort. Interpretation: Although the number of patients is limited, our results show that the antibody response against the first SARS-CoV-2 infection in symptomatic patients is typical of that observed in an acute viral infection. Funding: The Japan Agency for Medical Research and Development and the National Institutes of Allergy and Infectious Diseases.

Hepatitis A virus (HAV) causes transient acute infection, and little is known of viral shedding via the duodenum and into the intestinal environment, including the gut microbiome, from the period of infection until after the recovery of symptoms. Therefore, in this study, we aimed to comprehensively observe the amount of virus excreted into the intestinal tract, the changes in the intestinal microbiome, and the level of inflammation during the healing process. We used blood and stool specimens from patients with human immunodeficiency virus who were infected with HAV during the HAV outbreak in Japan in 2018. Moreover, we observed changes in fecal HAV RNA and quantified the plasma cytokine level and gut microbiome by 16S rRNA analysis from clinical onset to at least 6 months after healing. HAV was detected from clinical onset up to a period of more than 150 days. Immediately after infection, many pro-inflammatory cytokines were elicited, and some cytokines showed different behaviors. The intestinal microbiome changed significantly after infection (dysbiosis), and the dysbiosis continued for a long time after healing. These observations suggest that the immunocompromised state is associated with prolonged viral shedding into the intestinal tract and delayed recovery of the intestinal environment.

Reverse transcription-quantitative PCR (RT-qPCR)-based tests are widely used to diagnose coronavirus disease 2019 (COVID-19). As a result that these tests cannot be done in local clinics where RT-qPCR testing capability is lacking, rapid antigen tests (RATs) for COVID-19 based on lateral flow immunoassays are used for rapid diagnosis. However, their sensitivity compared with each other and with RT-qPCR and infectious virus isolation has not been examined. Here, we compared the sensitivity among four RATs by using severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) isolates and several types of COVID-19 patient specimens and compared their sensitivity with that of RT-qPCR and infectious virus isolation. Although the RATs read the samples containing large amounts of virus as positive, even the most sensitive RAT read the samples containing small amounts of virus as negative. Moreover, all RATs tested failed to detect viral antigens in several specimens from which the virus was isolated. The current RATs will likely miss some COVID-19 patients who are shedding infectious SARS-CoV-2.

HIV-1 escape from CTL is predictable based on the Human Leukocyte Antigen (HLA) class I alleles expressed by the host. As such, HIV-1 sequences circulating in a population of hosts will harbor escape mutations specific to the HLA alleles of that population. In theory, this should increase the frequency of escape mutation transmission to persons expressing the restricting HLA allele, thereby compromising host immunity to the incoming HIV-1 strain. However, the clinical impact of infection with HIV-1 containing immune escape mutations has not conclusively been demonstrated. Japan's population features limited HLA diversity which is driving population-level HIV adaptation: for example, >60% of Japanese express HLA-A*24:02 and its associated Nef-Y135F escape mutation represents the population consensus. As such, Japan is an ideal population in which to examine this phenomenon. Here, we combine genetic and immunological analyses to identify A*24:02-positive individuals likely to have been infected with Y135F-containing HIV-1. Over a ~5 year follow-up, these individuals exhibited significantly lower CD4 counts compared to individuals inferred to have been infected with wild-type HIV-1. Our results support a significant negative clinical impact of pathogen adaptation to host pressures at the population level.

BACKGROUND: Drug resistance (DR) of HIV-1 can be examined genotypically or phenotypically. Although sequencing is the gold standard of the genotypic resistance testing (GRT), high-throughput GRT targeted to the codons responsible for DR may be more appropriate for epidemiological studies and public health research. METHODS: We used a Japanese database to design and synthesize sequence-specific oligonucleotide probes (SSOP) for the detection of wild-type sequences and 6 DR mutations in the clade B HIV-1 reverse transcriptase region. We coupled SSOP to microbeads of the Luminex 100 xMAP system and developed a GRT based on the polymerase chain reaction (PCR)-SSOP-Luminex method. RESULTS: Sixteen oligoprobes for discriminating DR mutations from wild-type sequences at 6 loci were designed and synthesized, and their sensitivity and specificity were confirmed using isogenic plasmids. The PCR-SSOP-Luminex DR assay was then compared to direct sequencing using 74 plasma specimens from treatment-naïve patients or those on failing treatment. In the majority of specimens, the results of the PCR-SSOP-Luminex DR assay were concordant with sequencing results: 62/74 (83.8%) for M41, 43/74 (58.1%) for K65, 70/74 (94.6%) for K70, 55/73 (75.3%) for K103, 63/73 (86.3%) for M184 and 68/73 (93.2%) for T215. There were a number of specimens without any positive signals, especially for K65. The nucleotide position of A2723G, A2747G and C2750T were frequent polymorphisms for the wild-type amino acids K65, K66 and D67, respectively, and 14 specimens had the D67N mutation encoded by G2748A. We synthesized 14 additional oligoprobes for K65, and the sensitivity for K65 loci improved from 43/74 (58.1%) to 68/74 (91.9%). CONCLUSIONS: We developed a rapid high-throughput assay for clade B HIV-1 DR mutations, which could be customized by synthesizing oligoprobes suitable for the circulating viruses. The assay could be a useful tool especially for public health research in both resource-rich and resource-limited settings.