Determination of intracellular tenofovir-diphosphate and emtricitabine-triphosphate concentrations in dried blood spots for pre-exposure prophylaxis adherence.

OBJECTIVES: We measured the intracellular concentrations of tenofovir-diphosphate (TFV-DP) and emtricitabine-triphosphate (FTC-TP) in dried blood spots (DBS) for pre-exposure prophylaxis (PrEP) adherence using sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS). METHODS: A total of 191 DBS were obtained from 85 participants who were receiving tenofovir disoproxil fumarate (TDF; 300 mg) and emtricitabine (FTC; 200 mg) as PrEP at the Sexual Health Clinic, National Center for Global Health and Medicine, Tokyo, Japan. DBS punch (3 mm) added to 25 µL of 50% methanol and 400 µL of internal standard solution was used for solid phase extraction. Chromatographic separation was achieved on an Atlantis Premier BEH C18 AX Column (50 mm × 2.1 mm i.d.; particle size 1.7 µm) using gradient elution (flow rate: 0.6 mL/min); injection volume: 7 µL and run time: 5.5 min. Calibration curves for the two drugs were linear in the range 0.05-12.5 ng/punch. RESULTS: We determined the intracellular TFV-DP and FTC-TP concentrations in 191 DBS obtained from 85 patients administered with TDF and FTC as PrEP. The analytical performance data (calibration curve and QC samples) for all the analytical runs met the acceptance criteria. Intracellular concentrations of TFV-DP and FTC-TP in the DBS remained stable for at least 24 h after oral administration. CONCLUSIONS: A multiplex LC-MS/MS method was successfully developed for DBS, which can be useful for monitoring the levels of TFV-DP and FTC-TP in individuals receiving PrEP.

Preinfection Neutralizing Antibodies, Omicron BA.5 Breakthrough Infection, and Long COVID: A Propensity Score-Matched Analysis.

BACKGROUND: Data are limited on the role of preinfection humoral immunity protection against Omicron BA.5 infection and long coronavirus disease (COVID) development. METHODS: We conducted nested case-control analysis among tertiary hospital staff in Tokyo who donated blood samples in June 2022 (1 month before Omicron BA.5 wave), approximately 6 months after receiving a third dose of COVID-19 mRNA vaccine. We measured live virus-neutralizing antibody titers against wild type and Omicron BA.5, and anti-receptor-binding domain (RBD) antibody titers at preinfection, and compared them between cases and propensity-matched controls. Among the breakthrough cases, we examined association between preinfection antibody titers and incidence of long COVID. RESULTS: Preinfection anti-RBD and neutralizing antibody titers were lower in cases than controls. Neutralizing titers against wild type and Omicron BA.5 were 64% (95% confidence interval [CI], 42%-77%) and 72% (95% CI, 53%-83%) lower, respectively, in cases than controls. Individuals with previous Omicron BA.1/BA.2 infections were more frequent among controls than cases (10.3% vs 0.8%), and their Omicron BA.5 neutralizing titers were 12.8-fold higher than infection-naive individuals. Among cases, preinfection antibody titers were not associated with incidence of long COVID. CONCLUSIONS: Preinfection immunogenicity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may play a role in protecting against the Omicron BA.5 infection but not preventing long COVID.

4-phenylquinoline-8-amine induces HIV-1 reactivation and apoptosis in latently HIV-1 infected cells.

Combinational antiretroviral therapy (cART) dramatically suppresses the viral load to undetectable levels in human immunodeficiency virus (HIV)-infected patients. However, HIV-1 reservoirs in CD4+T cells and myeloid cells, which can evade cART and host antiviral immune systems, are still significant obstacles to HIV-1 eradication. The "Shock and Kill" approach using latently-reversing agents (LRAs) is therefore currently developing strategies for effective HIV-1 reactivation from latency and inducing cell death. Here, we performed small-molecular chemical library screening with monocytic HIV-1 latently-infected model cells, THP-1 Nluc #225, and identified 4-phenylquinoline-8-amine (PQA) as a novel LRA candidate. PQA induced efficient HIV-1 reactivation in combination with PKC agonists including Prostratin and showed a similar tendency for HIV-1 activation in primary HIV-1 reservoirs. Furthermore, PQA induced killing of HIV-1 latently-infected cells. RNA-sequencing analysis revealed PQA had different functional mechanisms from PKC agonists, and oxidative stress-inducible genes including DDIT3 or CTSD were only involved in PQA-mediated cell death. In summary, PQA is a potential LRA lead compound that exerts novel functions related to HIV-1 activation and apoptosis-mediated cell death to eliminate HIV-1 reservoirs.

N-(4-Hydroxyphenyl) Retinamide Suppresses SARS-CoV-2 Spike Protein-Mediated Cell-Cell Fusion by a Dihydroceramide Δ4-Desaturase 1-Independent Mechanism.

The membrane fusion between the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and host cells is essential for the initial step of infection; therefore, the host cell membrane components, including sphingolipids, influence the viral infection. We assessed several inhibitors of the enzymes pertaining to sphingolipid metabolism, against SARS-CoV-2 spike protein (S)-mediated cell-cell fusion and viral infection. N-(4-Hydroxyphenyl) retinamide (4-HPR), an inhibitor of dihydroceramide Δ4-desaturase 1 (DES1), suppressed cell-cell fusion and viral infection. The analysis of sphingolipid levels revealed that the inhibition efficiencies of cell-cell fusion and viral infection in 4-HPR-treated cells were consistent with an increased ratio of saturated sphinganine-based lipids to total sphingolipids. We investigated the relationship of DES1 with the inhibition efficiencies of cell-cell fusion. The changes in the sphingolipid profile induced by 4-HPR were mitigated by the supplementation with exogenous cell-permeative ceramide; however, the reduced cell-cell fusion could not be reversed. The efficiency of cell-cell fusion in DES1 knockout (KO) cells was at a level comparable to that in wild-type (WT) cells; however, the ratio of saturated sphinganine-based lipids to the total sphingolipids was higher in DES1 KO cells than in WT cells. 4-HPR reduced cell membrane fluidity without any significant effects on the expression or localization of angiotensin-converting enzyme 2, the SARS-CoV-2 receptor. Therefore, 4-HPR suppresses SARS-CoV-2 S-mediated membrane fusion through a DES1-independent mechanism, and this decrease in membrane fluidity induced by 4-HPR could be the major cause for the inhibition of SARS-CoV-2 infection. IMPORTANCE Sphingolipids could play an important role in SARS-CoV-2 S-mediated membrane fusion with host cells. We studied the cell-cell fusion using SARS-CoV-2 S-expressing cells and sphingolipid-manipulated target cells, with an inhibitor of the sphingolipid metabolism. 4-HPR (also known as fenretinide) is an inhibitor of DES1, and it exhibits antitumor activity and suppresses cell-cell fusion and viral infection. 4-HPR suppresses membrane fusion through a decrease in membrane fluidity, which could possibly be the cause for the inhibition of SARS-CoV-2 infection. There is accumulating clinical data on the safety of 4-HPR. Therefore, it could be a potential candidate drug against COVID-19.

Dihydroceramide Δ4-Desaturase 1 Is Not Involved in SARS-CoV-2 Infection.

Dihydroceramide Δ4-desaturase 1 (DEGS1) enzymatic activity is inhibited with N-(4-hydroxyphenyl)-retinamide (4-HPR). We reported previously that 4-HPR suppresses severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry through a DEGS1-independent mechanism. However, it remains unclear whether DEGS1 is involved in other SARS-CoV-2 infection processes, such as virus replication and release. Here we established DEGS1 knockout (KO) in VeroE6TMPRSS2 cells. No significant difference was observed in virus production in the culture supernatant between wild-type (WT) cells and DEGS1-KO cells, although the levels of dihydroceramide (DHCer), a DEGS1 substrate, were significantly higher in DEGS1-KO cells than WT cells. Furthermore, the virus-induced cytopathic effect was also observed in DEGS1-KO cells. Importantly, the EC50 value of 4-HPR in DEGS1-KO cells was almost identical to the value reported previously in WT cells. Our results indicated the lack of involvement of DEGS1 in SARS-CoV-2 infection.

Asymptomatic COVID-19 re-infection in a Japanese male by elevated half-maximal inhibitory concentration (IC50) of neutralizing antibodies.

INTRODUCTION: "Re-infection" with COVID-19 is a growing concern; re-infection cases have reported worldwide. However, the clinical characteristics of SARS-CoV-2 re-infection, including the levels and role of anti-SARS-CoV-2 Spike protein IgG antibodies and the half-maximal concentration (IC50) of neutralizing antibodies remain unknown. METHODS: Both the epidemiological and clinical information has been collected during two episodes of COVID-19 in a patient. Laboratory results, including RT-PCR, Ct values, anti-SARS-CoV-2 Spike protein IgG antibodies, and the IC50 of neutralizing antibodies levels were analyzed on the patient. RESULTS: The patient was a 58-year-old man who developed moderate COVID-19 pneumonia with oxygen demand (cannula 2 L/min) in the first episode. By day 30, he recuperated and was discharged after testing negative for SARS-CoV-2. After two and a half months, his three family members showed COVID-19 symptoms and tested positive for SARS-CoV-2. He tested positive for SARS-CoV-2 once again and was asymptomatic (the second episode). The IC50 of neutralizing antibodies against SARS-CoV-2 greatly increased from 50.0 µg/mL (after the first episode) to 14.8 µg/mL (after the second episode), and remained strongly reactive (20.1 µl/mL) after 47 days of the second episode. CONCLUSIONS: Epidemiological, clinical, and serological analyses confirmed that the patient had re-infection instead of persistent viral shedding from first infection. Our results suggest that SARS-CoV-2 re-infection may manifest as asymptomatic with increased neutralizing antibody levels. Further studies such as the virus characteristics, immunology, and epidemiology on SARS-CoV-2 re-infection are needed.

Benzolactam-related compounds promote apoptosis of HIV-infected human cells via protein kinase C-induced HIV latency reversal.

Latency-reversing agents (LRAs) are considered a potential strategy for curing cells of HIV-1 infection. Certain protein kinase C (PKC) activators have been previously reported to be LRAs because they can reverse HIV latency. In the present study, we examined the activities of a panel of benzolactam derivatives against cells latently infected with HIV. Using determination of p24 antigen in cell supernatants or altered intracellular GFP expression to measure HIV reactivation from latently infected cells along with a cytotoxicity assay, we found that some of the compounds exhibited latency-reversing activity, which was followed by enhanced release of HIV particles from the cells. One derivative, BL-V8-310, displayed activity in ACH-2 and J-Lat cells latently infected with HIV at a concentration of 10 nm or higher, which was superior to the activity of another highly active PKC activator, prostratin. These results were confirmed with peripheral blood cells from HIV-infected patients. We also found that these drugs up-regulate the expression of caspase 3 and enhance apoptosis specifically in latently HIV-infected cells. Moreover, combining BL-V8-310 with a bromodomain-containing 4 (BRD4) inhibitor, JQ1, not only enhanced HIV latency-reversing activity, but also reduced the effect on cytotoxic cytokine secretion from CD4+ T-cells induced by BL-V8-310 alone. Our results suggest that BL-V8-310 and its related benzolactam derivatives are potential LRA lead compounds that are effective in reversing HIV latency and reducing viral reservoirs in HIV-positive individuals with few adverse effects.

Full-genome analysis of hepatitis C virus in HIV-coinfected hemophiliac Japanese patients.

AIM: More than 1400 Japanese hemophiliacs acquired HIV infection around 1983 through contaminated blood products imported from the USA, most of whom also acquired hepatitis C virus (HCV) infection. To delineate the HCV genetic relations in HIV-coinfected hemophiliacs, we analyzed stocked plasma samples of the patients seen at the largest referral center for HIV care in Japan. METHODS: Hepatitis C virus full-genome sequences were amplified and determined using next-generation sequencing, and genotyping and phylogenetic analyses of these sequences were carried out. The results of these hemophiliacs were compared with those of previously studied HIV-coinfected Japanese non-hemophiliacs who had undergone similar analysis of HCV full-genome sequences. RESULTS: From 1997 to the end of 2017, 72 HIV-infected Japanese hemophiliacs regularly visited our outpatient clinic. Of these, 51 patients had detectable plasma HCV-RNA. The HCV full genome was successfully amplified and sequenced in 50 patients. Not only HCV genotypes 1b (28%) and 2a (6%), which are common in Japan, but also HCV genotypes 1a (32%) and 3a (22%) were identified at high frequency. A single case of intergenotypic recombinant form (2b/1a) and a single case of mixed infection (1a and 3a) were also identified. Each sequence derived from hemophiliacs was more than 0.05 genetic distance away from the other sequences in phylogenetic analysis. CONCLUSIONS: Various HCV genotypes were identified in Japanese hemophiliacs, a finding that reflects the HCV genotypic distribution in the USA. The genetic distance among them are the results of viral evolution in each patient plus HCV genetic diversity in the USA.

High-performance liquid chromatography-tandem mass spectrometry for simultaneous determination of raltegravir, dolutegravir and elvitegravir concentrations in human plasma and cerebrospinal fluid samples.

A simple sample treatment procedure and sensitive liquid chromatography-tandem mass spectrometry method were developed for the simultaneous quantification of the concentrations of human immunodeficiency virus-1 integrase strand transfer inhibitors - raltegravir, dolutegravir and elvitegravir - in human plasma and cerebrospinal fluid (CSF). Plasma and CSF samples (20 µL each) were deproteinized with acetonitrile. Raltegravir-d3 was used as the internal standard. Chromatographic separation was achieved on an XBridge C18 column (50 × 2.1 mm i.d., particle size 3.5 µm) using acetonitrile-water (7:3, v/v) containing 0.1% formic acid as the mobile phase at a flow rate of 0.2 mL/min. The run time was 5 min. Calibration curves for all three drugs were linear in the range 5-1500 ng/mL for plasma and 1-200 ng/mL for CSF. The intra- and inter-day precision and accuracy of all three drugs in plasma were coefficient of variation (CV) <12.9% and 100.0 ± 12.2%, respectively, while those in CSF were CV <12.3% and 100.0 ± 7.9%, respectively. Successful validation under the same LC-MS/MS conditions for both plasma and CSF indicates this analytical method is useful for monitoring the levels of these integrase strand transfer inhibitors in the management of treatment of HIV-1 carriers.

High plasma concentrations of dolutegravir in patients with ABCG2 genetic variants.

The ATP-binding cassette transporters B1 (ABCB1) and G2 (ABCG2) are both expressed in the intestine and known as efflux transporters of drugs. Dolutegravir was identified recently as a substrate of both ABCB1 and ABCG2. This study aimed to determine the relations between single-nucleotide polymorphisms of ABCB1 and ABCG2 genes and plasma dolutegravir concentrations. Plasma samples were obtained from 42 HIV-1-infected patients treated with dolutegravir-containing regimens 0.5-4 h after dolutegravir dosing. Plasma dolutegravir concentrations were measured by liquid chromatography-mass spectrometry. Genomic DNA was isolated from peripheral blood mononuclear cells. Genotyping of allelic variants of ABCB1 1236 C>T (rs1128503), 2677 G>T/A (rs2032582), 3435 C>T (rs1045642), 4036 A>G (rs3842), and ABCG2 421 C>A (rs2231142) was performed using the TaqMan drug metabolism assays. None of the genotypes in ABCB1 1236 C>T, 2677 G>T/A, 3435 C>T, and 4036 A>G correlated with plasma dolutegravir concentration. In contrast, the mean peak plasma concentration of dolutegravir was significantly higher in the genotypes of ABCG2 421 AA (5002 ng/ml, n=3) compared with the genotypes of ABCG2 421 CC (2569 ng/ml, n=22) and ABCG2 421 CA (2479 ng/ml, n=17) (P=0.0005). The speculated peak level of plasma dolutegravir concentration was significantly higher in ABCG2 genetic variant holders, probably, at least in part, because of low expression levels of efflux transporters in the intestines associated with these genetic variants.

Rilpivirine resistance mutation E138K in HIV-1 reverse transcriptase predisposed by prevalent polymorphic mutations.

BACKGROUND: Rilpivirine is listed as a recommended or alternative key drug in the current ART guidelines. E138K in HIV-1 reverse transcriptase (RT) is a primary mutation in resistance to rilpivirine, although in vitro experiments showed it confers only <3-fold resistance. An unidentified mechanism could amplify resistance to rilpivirine conferred by E138K. OBJECTIVES: The objective of this study was to reveal the mechanism amplifying rilpivirine resistance conferred by E138K. PATIENTS AND METHODS: HIV-1 RT sequences were compared in patients who failed rilpivirine-containing ART virologically. The effects of mutations commonly identified with E138K on rilpivirine susceptibility were analysed by using recombinant HIV-1 variants. RESULTS: Rilpivirine-containing ART was introduced in 162 HIV-1-infected patients at the outpatient clinic of the AIDS Clinical Center (National Center for Global Health and Medicine, Tokyo, Japan) between May 2012 and June 2015. Virological treatment failure occurred in six of these patients. E138K emerged in three patients while other rilpivirine resistance mutations emerged in the other three patients. I135T/L were identified in only three patients with E138K and existed before the introduction of rilpivirine-containing ART. Analysis of recombinant HIV-1 variants indicated that E138K conferred low-level rilpivirine resistance and that coexistence of I135T/L with E138K amplified the resistance. CONCLUSIONS: I135T/L, escape mutations from HLA-B*51/52-restricted cytotoxic T lymphocytes, which are prevalent in Japan, may predispose HIV-1 to harbour E138K upon failure of rilpivirine-containing ART. The mutation patterns of drug resistance may vary due to baseline polymorphic mutations.

Sphingomyelin synthase 2, but not sphingomyelin synthase 1, is involved in HIV-1 envelope-mediated membrane fusion.

Membrane fusion between the viral envelope and plasma membranes of target cells has previously been correlated with HIV-1 infection. Lipids in the plasma membrane, including sphingomyelin, may be crucially involved in HIV-1 infection; however, the role of lipid-metabolic enzymes in membrane fusion remains unclear. In this study, we examined the roles of sphingomyelin synthase (SMS) in HIV-1 Env-mediated membrane fusion using a cell-cell fusion assay with HIV-1 mimetics and their target cells. We employed reconstituted cells as target cells that stably express Sms1 or Sms2 in Sms-deficient cells. Fusion susceptibility was ∼5-fold higher in Sms2-expressing cells (not in Sms1-expressing cells) than in Sms-deficient cells. The enhancement of fusion susceptibility observed in Sms2-expressing cells was reversed and reduced by Sms2 knockdown. We also found that catalytically nonactive Sms2 promoted membrane fusion susceptibility. Moreover, SMS2 co-localized and was constitutively associated with the HIV receptor·co-receptor complex in the plasma membrane. In addition, HIV-1 Env treatment resulted in a transient increase in nonreceptor tyrosine kinase (Pyk2) phosphorylation in Sms2-expressing and catalytically nonactive Sms2-expressing cells. We observed that F-actin polymerization in the region of membrane fusion was more prominent in Sms2-expressing cells than Sms-deficient cells. Taken together, our research provides insight into a novel function of SMS2 which is the regulation of HIV-1 Env-mediated membrane fusion via actin rearrangement.

Single-nucleotide polymorphisms in the UDP-glucuronosyltransferase 1A-3' untranslated region are associated with atazanavir-induced nephrolithiasis in patients with HIV-1 infection: a pharmacogenetic study.

OBJECTIVES: Ritonavir-boosted atazanavir (atazanavir/ritonavir) is a widely used antiretroviral drug, though it can potentially cause nephrolithiasis. The aim of this study was to determine the relationship between polymorphisms in genes encoding proteins involved in metabolism and transportation of atazanavir, and atazanavir/ritonavir-induced nephrolithiasis in HIV-1-infected patients treated with atazanavir/ritonavir. METHODS: Nineteen SNPs in the ABCB1, NR1I2, UGT1A1, SLCO1B1 and CYP3A5 genes were examined in case patients with atazanavir/ritonavir-induced nephrolithiasis (n = 31) and controls (n = 47). Case patients were those with a clinical diagnosis of nephrolithiasis while on atazanavir/ritonavir, based on new-onset acute flank pain plus one of the following: (i) new-onset haematuria; (ii) documented presence of stones by either abdominal ultrasonography or CT; or (iii) confirmed stone passage. Control patients were consecutively enrolled among those with >2 years of atazanavir/ritonavir exposure free of nephrolithiasis. Genotyping was performed by allelic discrimination using TaqMan 5'-nuclease assays with standard protocols. Associations between alleles and atazanavir/ritonavir-induced nephrolithiasis were tested by univariate and multivariate logistic regression analyses. RESULTS: Multivariate analysis showed a significant association between atazanavir/ritonavir-induced nephrolithiasis and genotype T/C versus C/C at position c.211 (adjusted OR = 3.7; 95% CI, 1.13-11.9; P = 0.030), genotype G/C versus C/C at 339 (adjusted OR = 5.8; 95% CI, 1.56-21.3; P = 0.009) and genotype G/G or G/C versus C/C at 440 (adjusted OR = 5.8; 95% CI, 1.56-21.3; P = 0.009) of the UGT1A-3' untranslated region (UTR). CONCLUSIONS: This is the first known study to identify the association between SNPs in the UGT1A-3'-UTR and atazanavir-induced nephrolithiasis. Further studies are warranted to confirm this association and to elucidate how these SNPs might influence atazanavir exposure.

Two-dimensional array of particles originating from dipole-dipole interaction as evidenced by potential curve measurements at vertical oil/water interfaces.

We propose a new method to evaluate the interaction potential energy between the particles adsorbed at an oil/water interface as a function of interparticle distance. The method is based on the measurement of the interparticle distance at a vertical oil/water interface, at which the gravitational force is naturally applied to compress the particle monolayer in the in-plane direction. We verified the method by examining whether we obtained the same potential curve upon varying the gravitational acceleration by tilting the interface. The present method is applicable in the force range from ∼0.1 to ∼100 pN, determined by the effective weight of the particles at the interface. The method gives a rather simple procedure to estimate a long range interaction among the particles adsorbed at oil/water interfaces. We applied this method to polystyrene particles at the decane/aqueous surfactant solution interface, and obtained the interparticle potential curves. All the potential curves obtained by the present method indicated that the interparticle repulsion is due to the electrical dipole-dipole interaction based on the negative charge of the particles. The mechanism of the dipole-dipole interaction is further discussed on the basis of the effects of surfactants.

High diagnostic accuracy of quantitative SARS-CoV-2 spike-binding-IgG assay and correlation with in vitro viral neutralizing activity.

Background: Antibody testing can easily evaluate the clinical status of patients, aid in the diagnosis of multisystem inflammatory syndrome, and monitor the immunity level in the population. However, the applicability of serological tests in detecting antibodies against the severe acute respiratory syndrome 2 (SARS-CoV-2) spike-binding protein remains limited. This study aimed to quantify both serum-derived neutralizing immunoglobulin-G (IgG) antibody activity and the amount of anti-SARS-CoV-2 Spike-IgG (S-IgG) in convalescent sera/plasmas and evaluate the direct correlation between the in vitro IgG-EC50 values and S-IgG values. Methods: We evaluated the neutralizing activity of purified IgG (IgG-EC50), quantified S-IgG in the serum/plasma of consecutive COVID-19 convalescent individuals using a cell-based virus-neutralizing assay, and determined the correlation between IgG-EC50 and S-IgG. In addition, we evaluated rational cut-off values using the receiver operating characteristic (ROC) curve and calculated the sensitivity and specificity of the quantitative S-IgG assay for moderate and high IgG-EC50. Results: A high correlation was observed between S-IgG and IgG-EC50 with a Spearman's ρ value of -0.748 (95 % confidence interval [CI]: -0.804-0.678). Using an IgG-EC50 of 50 µg/mL and 20 µg/mL as the cut-off values for moderate and high in vitro neutralizing activity, respectively, the Youden's index values of 287.5 binding antibody units (BAU)/mL and 454.1 BAU/mL determined from the ROC curve showed the highest diagnostic accuracy, with Kappa values of 0.884 (95 % CI: 0.823-0.946) and 0.920 (95 % CI: 0.681-0.979), respectively. Conclusions: Quantitative S-IgG tests are a useful and convenient tool for estimating in vitro virus-neutralizing activity, with a high correlation with IgG-EC50 when the rational cut-off value is carefully determined.

Naturally selected rilpivirine-resistant HIV-1 variants by host cellular immunity.

BACKGROUND: Rilpivirine is listed as an alternative key drug in current antiretroviral therapy (ART) guidelines. E138G/A/K in human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) are rilpivirine resistance-associated mutations and can be identified in a few ART-naive patients, although at low frequency. The 138th position in HIV-1 RT is located in one of the putative epitopes of human leukocyte antigen (HLA)-B*18-restricted cytotoxic T lymphocytes (CTLs). CTL-mediated immune pressure selects escape mutations within the CTL epitope. Here we tested whether E138G/A/K could be selected by HLA-B*18-restricted CTLs. METHODS: The amino acid variation at the 138th position was compared between ART-naive HIV-1-infected patients with and without HLA-B*18. The optimal epitope containing the 138th position was determined and the impact of E138G/A/K on CTL response was analyzed by epitope-specific CTLs. The effect of E138G/A/K on drug susceptibility was determined by constructing recombinant HIV-1 variants. RESULTS: The prevalence of E138G/A/K was 21% and 0.37% in 19 and 1088 patients with and without HLA-B*18, respectively (odds ratio, 72.3; P = 4.9 × 10(-25)). The CTL response was completely abolished by the substitution of E138G/A/K in the epitope peptide. E138G/A/K conferred 5.1-, 7.1-, and 2.7-fold resistance to rilpivirine, respectively. CONCLUSIONS: E138G/A/K can be selected by HLA-B*18-restricted CTLs and confer significant rilpivirine resistance. We recommend drug resistance testing before the introduction of rilpivirine-based ART in HLA-B*18-positive patients.

Role of P-glycoprotein in the efflux of raltegravir from human intestinal cells and CD4+ T-cells as an interaction target for anti-HIV agents.

Cellular efflux and uptake transports of several anti-HIV agents are mediated by plasma membrane-localized solute transporters. However, transporters involved in raltegravir disposition have not been fully characterized. Here, we performed in vitro studies to identify transporters mediating transcellular transport of raltegravir. Transepithelial raltegravir transport was examined using porcine kidney epithelial cell line (LLC-PK1) and LLC-PK1 cells stably transfected with P-glycoprotein (also known as Multiple drug resistance 1) (L-MDR1). Transepithelial transport of raltegravir in Caco-2 cell monolayers, and intracellular accumulation of raltegravir in the MT-2 and MT-4 (CD4+ T-) cells were measured in the presence or absence of anti-HIV agents. The uptake of raltegravir was investigated in HEK-293 cells expressing each of several solute carrier family transporters. The apical-to-basal raltegravir transport was significantly decreased in L-MDR1 as compared to that in LLC-PK1 monolayers. In HEK-293 cells expressing breast cancer resistance protein (BCRP), raltegravir accumulation was lower than that in the mock-transfected cells. In Caco-2 cells, protease inhibitors including nelfinavir, ritonavir and lopinavir enhanced the apical-to-basal transport of raltegravir. By contrast, reverse transcriptase inhibitors such as zidovudine, efavirenz, and nevirapine, had no effect on raltegravir transport. The cellular accumulation of raltegravir in MT-2 cells, which express P-glycoprotein, was significantly increased in the presence of protease inhibitors. By contrast, protease inhibitors only marginally increased the accumulation of raltegravir in MT-4 cells, in which P-glycoprotein is not expressed. The present findings suggest that raltegravir is a substrate of both P-glycoprotein and BCRP. Protease inhibitors increase the absorptive transport of raltegravir in Caco-2 cells, and the cellular accumulation in T-cells, at least in part, by P-glycoprotein-mediated interaction.

Assessing the effects of antiretroviral therapy-latency-reversing agent combination therapy on eradicating replication-competent HIV provirus in a Jurkat cell culture model.

Eradication of HIV-1 latently infected cells is an important issue in HIV treatment. However, there are limited models available to assess therapeutic efficacy in vitro. Here, we present a protocol for establishing a variety of HIV-infected Jurkat cells, including productive and latent status, evaluating the efficacy of antiviral agents, followed by PCR/sequencing-based detection of replication competent HIV provirus. This protocol is useful for optimization of treatment of HIV-1 and provides insights into the mechanisms of clonal selection of heterogeneous HIV-1-infected cells. For complete details on the use and execution of this protocol, please refer to Matsuda et al. (2021).1.

Steady-state pharmacokinetics of plasma tenofovir alafenamide (TAF), tenofovir (TFV) and emtricitabine (FTC), and intracellular TFV-diphosphate and FTC-triphosphate in HIV-1 infected old Japanese patients treated with bictegravir/FTC/TAF.

Emtricitabine (FTC) plus tenofovir alafenamide (TAF) has demonstrated efficacy and safety for pre-exposure prophylaxis (PrEP) to prevent HIV-1 infection. We measured the plasma PK of FTC, tenofovir (TFV), and TAF in a steady-state pharmacokinetic (PK) study of bictegravir/FTC/TAF in HIV-1-infected patients. Furthermore, validated liquid chromatography-tandem mass spectrometry was used to measure intracellular TFV-diphosphate (DP) and FTC-triphosphate (TP), the active metabolites of TFV and FTC, respectively. Plasma and dried blood spot samples were collected from 10 male patients aged ≥ 50 years at various time intervals: 0 (trough), 1, 2, 3, 4, 6, 8, 12, and 24 h after drug administration. The mean ± standard deviation of plasma PK parameters were as follows: The maximum concentrations of TAF, TFV, and FTC were 104.0 ± 72.5, 27.9 ± 5.2, and 3,976.0 ± 683.6 ng/mL, respectively. Additionally, their terminal elimination half-lives were 0.6 ± 0.5, 31.6 ± 10.4, and 6.9 ± 1.4 h, respectively. These results were consistent with previously reported data. The intracellular levels of TFV-DP and FTC-TP varied widely among individuals; however, they remained stable over 24 h in each individual at approximately 1,000-1,500 and 2,000-3,000 fmol/punch, respectively, indicating that plasma concentrations did not affect the intracellular concentrations of their active metabolites. These results demonstrated that measuring intracellular TFV-DP and FTC-TP could be useful for monitoring adherence to PrEP in clients on this regimen.