Abstract The hepatitis C virus (HCV) nonstructural 5A (NS5A) phosphoprotein has been intensely studied due to its ability to subvert the host interferon-induced antiviral response. However, more ...recent studies suggest that it may also play an important regulatory role in HCV RNA replication as well as modulate host intracellular signaling pathways. Phosphorylation of NS5A appears to be a highly regulated process and several cellular protein kinases responsible for NS5A phosphorylation have been identified in vitro . Studies utilizing the HCV replicon cell culture system have suggested a provocative role for the differential phosphorylation of NS5A in the regulation of viral RNA replication through its association with the viral replication complex, including several host cell factors. Importantly, recent in vivo data linking loss of NS5A hyperphosphorylation to non-productive HCV replication in the chimpanzee model have provided high validation for targeting the cellular kinases involved, particularly the kinases responsible for NS5A phosphorylation, for antiviral therapeutic intervention. Understanding the process of NS5A phosphorylation and the definite identification of the culprit cellular protein kinase(s) will shed light on the mechanisms of HCV RNA replication and/or pathogenesis.
4-anilino quinazolines have been identified as inhibitors of HCV replication. The target of this class of compounds was proposed to be the viral protein NS5A, although unequivocal proof has never ...been presented. A 4-anilino quinazoline moiety is often found in kinase inhibitors, leading us to formulate the hypothesis that the anti-HCV activity displayed by these compounds might be due to inhibition of a cellular kinase. Type III phosphatidylinositol 4-kinase α (PI4KIIIα) has recently been identified as a host factor for HCV replication. We therefore evaluated AL-9, a compound prototypical of the 4-anilino quinazoline class, on selected phosphatidylinositol kinases. AL-9 inhibited purified PI4KIIIα and, to a lesser extent, PI4KIIIβ. In Huh7.5 cells, PI4KIIIα is responsible for the phosphatidylinositol-4 phosphate (PI4P) pool present in the plasma membrane. Accordingly, we observed a gradual decrease of PI4P in the plasma membrane upon incubation with AL-9, indicating that this agent inhibits PI4KIIIα also in living cells. Conversely, AL-9 did not affect the level of PI4P in the Golgi membrane, suggesting that the PI4KIIIβ isoform was not significantly inhibited under our experimental conditions. Incubation of cells expressing HCV proteins with AL-9 induced abnormally large clusters of NS5A, a phenomenon previously observed upon silencing PI4KIIIα by RNA interference. In light of our findings, we propose that the antiviral effect of 4-anilino quinazoline compounds is mediated by the inhibition of PI4KIIIα and the consequent depletion of PI4P required for the HCV membranous web. In addition, we noted that HCV has a profound effect on cellular PI4P distribution, causing significant enrichment of PI4P in the HCV-membranous web and a concomitant depletion of PI4P in the plasma membrane. This observation implies that HCV - by recruiting PI4KIIIα in the RNA replication complex - hijacks PI4P metabolism, ultimately resulting in a markedly altered subcellular distribution of the PI4KIIIα product.
Alongside vaccines, antiviral drugs are becoming an integral part of our response to the SARS‐CoV‐2 pandemic. Nirmatrelvir—an orally available inhibitor of the 3‐chymotrypsin‐like cysteine ...protease—has been shown to reduce the risk of progression to severe COVID‐19. However, the impact of nirmatrelvir treatment on the development of SARS‐CoV‐2‐specific adaptive immune responses is unknown. Here, by using mouse models of SARS‐CoV‐2 infection, we show that nirmatrelvir administration blunts the development of SARS‐CoV‐2‐specific antibody and T cell responses. Accordingly, upon secondary challenge, nirmatrelvir‐treated mice recruited significantly fewer memory T and B cells to the infected lungs and mediastinal lymph nodes, respectively. Together, the data highlight a potential negative impact of nirmatrelvir treatment with important implications for clinical management and might help explain the virological and/or symptomatic relapse after treatment completion reported in some individuals.
Synopsis
Nirmatrelvir administration to SARS‐CoV‐2‐infected mice blunts the development of SARS‐CoV‐2‐specific antibody and T cell responses.
Accordingly, upon secondary challenge, nirmatrelvir‐treated mice recruited significantly fewer memory T and B cells.
Adaptive immune response is impaired across different SARS‐CoV‐2 variants and regardless of the time of treatment.
Our results might help explain the virological and/or symptomatic relapse after treatment completion reported in some individuals.
Nirmatrelvir administration to SARS‐CoV‐2‐infected mice blunts the development of SARS‐CoV‐2‐specific antibody and T cell responses.
Vaccines against COVID-19 are a powerful tool to control the current SARS-CoV-2 pandemic. A thorough description of their immunogenicity among people living with HIV (PLWHIV) is necessary. We aimed ...to assess the immunogenicity of the mRNA-1273 vaccine among PLWHIV.
In this prospective cohort, adult PLWHIV outpatients were enrolled during the Italian vaccination campaign. Enrolment was allowed irrespective of ongoing combination antiretroviral therapy (ART), plasma HIV viral load and CD4+ T cell count. A two-dose regimen of mRNA-1273, with administrations performed 28 days apart, was employed. The primary outcomes were anti-spike (anti-S) antibody titres and neutralising antibody activity, assessed 28 days after completing the vaccination schedule. A convenient sample of individuals not affected by HIV was also collected to serve as control (referred as healthy-donors, HDs).
We enrolled 71 PLWHIV, mostly male (84·5%), with a mean age of 47 years, a median CD4+ T cell count of 747·0 cells per µL and a median HIV viral load <50 copies/mL. COVID-19-experienced PLWHIV displayed higher anti-S antibody titres (p=0·0007) and neutralising antibody activity in sera (p=0·0007) than COVID-19-naïve PLWHIV. When stratified according to CD4+ T cell count (<350 cells/μL, 350-500 cells/μL, >500 cells/μL), anti-S antibody titres (6/71, median 2173 U/mL IQR 987-4109; 7/71, 5763 IU/mL IQR 4801->12500; 58/71, 2449 U/mL IQR 1524-5704) were not lower to those observed among HDs (10, median 1425 U/mL IQR 599-6131). In addition, neutralising antibody activity, stratified according to the CD4+ T cell count (6/71, median 1314 IQR 606-2477; 7/71, 3329 IU/mL IQR 1905-10508; 58/71, 1227 U/mL IQR 761-3032), was like those displayed by HDs (10, median 2112 U/mL IQR 719-8889).
In our cohort of PLWHIV with well-controlled ART, stable viral suppression and robust CD4+ T cell count, inoculation with mRNA-1273 vaccine given 4 weeks apart produced detectable humoral immune response, similar to individuals without HIV infection, supporting vaccination in PLWHIV.
This study was partially supported by Italian Ministry of Health Ricerca Corrente 2021, by Intesa San Paolo COVID-19 emergency 2020 funds, and by Fondazione Cariplo Grant (INNATE-CoV).
Single nucleotide polymorphisms (SNPs) near the interleukin 28B (IL28B) region are the strongest baseline predictors of a sustained virologic response (SVR) to peg‐interferon (PegIFN) and ribavirin ...(Rbv) in patients with hepatitis C virus (HCV) genotype 1 infection. Whether this holds true for HCV‐4 patients too is unknown. The aim was to investigate the predictive power of the rs12979860 IL28B SNP for a response to Peg‐IFN and Rbv in HCV‐4 patients. All HCV‐4 patients consecutively treated between September 2004 and June 2010 with PegIFN and Rbv at two liver centers at the Maggiore Hospital Milan (Italy) underwent TaqMan SNP Genotyping assays for testing rs12979860 genotype. Of 112 treated patients (98 males, 75 of Egyptian descent, 26 with cirrhosis) 103 were included in the final analysis; five discontinued treatment for nonvirologic reasons and four did not consent to genetic testing. Twenty‐four (23%) were genotype CC, 65 (63%) CT, and 14 (14%) TT. Overall, 50 (49%) achieved an SVR: 21 (88%) CC patients versus 29 (37%) CT/TT (P < 0.0001). CC patients more often had a rapid virologic response (RVR) than CT/TT patients (12, 50% versus 23, 29%; P = 0.08), while also showing lower relapse rates (0% 0/21 versus 36% 16/45 P = 0.0013). In non‐RVR patients, SVR rates were higher in CC than CT/TT patients (9 75% versus 13 23% P = 0.001). By logistic regression, the IL28B rs12979860 CC genotype was an independent predictor of SVR with an odds ratio of 8.0 (95% confidence interval 2.00‐32.01; P = 0.003). Conclusion: The IL28B rs12979860 SNP may have an added value in the treatment algorithm of HCV‐4 patients because it is the strongest predictor of an SVR to PegIFN/Rbv therapy. (HEPATOLOGY 2012)
We report here synthesis and SAR of substituted piperazinyl-
N-(aryl)benzamides as potent inhibitors of HCV replication exerted via modulation of the dimerization of NS5A.
The RNA replication ...machinery of HCV is a multi-subunit membrane–associated complex. NS5A has emerged as an active component of HCV replicase, possibly involved in regulation of viral replication and resistance to the antiviral effect of interferon. We report here substituted piperazinyl-
N-(aryl)benzamides as potent inhibitors of HCV replication exerted via modulation of the dimerization of NS5A.
The evolution of a novel series of HDAC inhibitors containing an unusual ketone zinc binding group is described. SAR studies resulted in optimization to potent, low molecular weight, selective, ...non-hydroxamic acid HDAC inhibitors.
Histone deacetylase (HDAC) inhibitors offer a promising strategy for cancer therapy and the first generation HDAC inhibitors are currently in clinical trials. A structurally novel series of HDAC inhibitors based on the natural cyclic tetrapeptide Apicidin is described. Selected screening of the sample collection looking for
L-2-amino-8-oxodecanoic acid (
L-Aoda) derivatives identified a small acyclic lead molecule
1 with the unusual ketone zinc binding group. SAR studies around this lead resulted in optimization to potent, low molecular weight, selective, non-hydroxamic acid HDAC inhibitors, equipotent to current clinical candidates.
Mutations within PCSK9 (proprotein convertase subtilisin/kexin type 9) are associated with dominant forms of familial hyper- and hypocholesterolemia. Although PCSK9 controls low density lipoprotein ...(LDL) receptor (LDLR) levels post-transcriptionally, several questions concerning its mode of action remain unanswered. We show that purified PCSK9 protein added to the medium of human endothelial kidney 293, HepG2, and Chinese hamster ovary cell lines decreases cellular LDL uptake in a dose-dependent manner. Using this cell-based assay of PCSK9 activity, we found that the relative potencies of several PCSK9 missense mutants (S127R and D374Y, associated with hypercholesterolemia, and R46L, associated with hypocholesterolemia) correlate with LDL cholesterol levels in humans carrying such mutations. Notably, we found that in vitro wild-type PCSK9 binds LDLR with an ∼150-fold higher affinity at an acidic endosomal pH (KD = 4.19 nm) compared with a neutral pH (KD = 628 nm). We also demonstrate that wild-type PCSK9 and mutants S127R and R46L are internalized by cells to similar levels, whereas D374Y is more efficiently internalized, consistent with their affinities for LDLR at neutral pH. Finally, we show that LDL diminishes PCSK9 binding to LDLR in vitro and partially inhibits the effects of secreted PCSK9 on LDLR degradation in cell culture. Together, the results of our biochemical and cell-based experiments suggest a model in which secreted PCSK9 binds to LDLR and directs the trafficking of LDLR to the lysosomes for degradation.
COVID-19 has proven to be particularly serious and life-threatening for patients presenting with pre-existing pathologies. Patients affected by rheumatic musculoskeletal disease (RMD) are likely to ...have impaired immune responses against SARS-CoV-2 infection due to their compromised immune system and the prolonged use of disease-modifying anti-rheumatic drugs (DMARDs), which include conventional synthetic (cs) DMARDs or biologic and targeted synthetic (b/ts) DMARDs. To provide an integrated analysis of the immune response following SARS-CoV-2 infection in RMD patients treated with different classes of DMARDs we carried out an immunological analysis of the antibody responses toward SARS-CoV-2 nucleocapsid and RBD proteins and an extensive immunophenotypic analysis of the major immune cell populations. We showed that RMD individuals under most DMARD treatments mount a sustained antibody response to the virus, with neutralizing activity. In addition, they displayed a sizable percentage of effector T and B lymphocytes. Among b-DMARDs, we found that anti-TNFα treatments are more favorable drugs to elicit humoral and cellular immune responses as compared to CTLA4-Ig and anti-IL6R inhibitors. This study provides a whole picture of the humoral and cellular immune responses in RMD patients by reassuring the use of DMARD treatments during COVID-19. The study points to TNF-α inhibitors as those DMARDs permitting elicitation of functional antibodies to SARS-CoV-2 and adaptive effector populations available to counteract possible re-infections.
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