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Innate immune responses are important in the control of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication. We have previously found a lactic acid bacteria species, Lactococcus lactis strain Plasma (LC-Plasma), which possesses specific feature to activate plasmacytoid dendritic cells (pDCs) and thus may affect innate immune responses. Here, we investigated the impact of pDC activation by LC-Plasma on SARS-CoV-2 replication in vitro. Addition of the culture supernatant of pDCs stimulated with LC-Plasma resulted in suppression of SARS-CoV-2 replication in Vero and Calu-3 cells. We confirmed interferon-α (IFN-α) secretion in the supernatant of pDCs stimulated with LC-Plasma and induction of IFN-stimulated genes in cells treated with the pDC supernatant. Anti-IFN-α antibody impaired the suppression of SARS-CoV-2 replication by the supernatant of LC-Plasma-stimulated pDCs, suggesting that IFN-α plays an important role in the SARS-CoV-2 suppression. Our results indicate the potential of LC-Plasma to induce inhibitory responses against SARS-CoV-2 replication through pDC stimulation with IFN-α secretion., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests. Hiroshi Ishii, Kenta Jounai, Konomi Ohshio, Daisuke Fujiwara, and Tetsuro Matano have patent #PCT/JP2022/40242 pending to Licensee., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objectives: Human Leukocyte Antigen HLA-B*57:01 and B*58:01 are considered anti-HIV-1 protective alleles. HLA-B*57:01/58:01-restricted HIV-1 Gag TW10 (TSTLQEQIGW, Gag residues 240-249) epitope-specific CD8 + T cell responses that frequently select for a Gag escape mutation, T242N, with viral fitness cost are crucial for HIV-1 control. Although this finding has been observed in cohorts where HIV-1 subtype B or C predominates, the protective impact of HLA-B*57:01/58:01 has not been reported in Southeast Asian countries where HIV-1 CRF01_AE is the major circulating strain. Here, the effect of HLA-B*57:01/58:01 on CRF01_AE infection was investigated., Methods: The correlation of HLA-B*57:01/58:01 with viral load and CD4 counts were analyzed in the CRF01_AE-infected Vietnamese cohort (N = 280). The impact of the T242N mutation on CRF01_AE replication capacity was assessed., Results: HLA-B*57:01/58:01-positive individuals mostly had HIV-1 with T242N (62/63) but showed neither a significant reduction in viral load nor increased CD4 counts relative to B*57:01/58:01-negative participants. In vitro and in vivo analyses revealed a significant reduction in viral fitness of CRF01_AE with T242N. In silico analysis indicated reduced presentation of epitopes in the context of CRF01_AE compared to subtype B or C in 10/16 HLA-B*57:01/58:01-restricted HIV-1 epitopes., Conclusion: The protective impact of HLA-B*57:01/58:01 on CRF01_AE infection is impaired despite strong suppressive pressure by TW10-specific CD8 + T cells., Competing Interests: Declaration of competing interest The authors have no competing interests to declare., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

CD8 + T-cell responses exert strong suppressive pressure on viral replication and select for viral escape mutations in HIV infection. Multiple viral epitopes restricted by major histocompatibility complex class I (MHC-I) are targeted by CD8 + T cells. Sequential selection of viral escape mutations in individual epitope-coding regions could result in failure in CD8 + T cell-based viral control leading to disease progression. However, how this sequential selection of epitope mutations occurs has not fully been determined. Here, we examined sequential selection of viral mutations in seven CD8 + T-cell epitope-coding regions in a macaque AIDS model of simian immunodeficiency virus mac239 (SIVmac239) infection. In seven SIVmac239-infected Burmese rhesus macaques possessing MHC-I haplotype 90-120-Ia, selection of viral mutations was observed in five to seven of the seven 90-120-Ia-associated CD8 + T-cell epitope-coding regions in a year post-infection. Of the seven CD8 + T-cell epitopes, viral mutation selection was detected first at two epitopes, Gag 206-216 and Nef 9-19 , but was found finally at Vif 114-124 epitope in most animals. Viral loads in 6 months were significantly associated with the number of mutated CD8 + T-cell epitope-coding regions 1 year post-infection. Tetramer analysis revealed early induction of Gag 241-249 specific CD8 + T-cell responses, which did not always result in early selection of viral mutations in the Gag 241-249 epitope, suggesting that the order of epitope mutation selection may not be determined only by immunodominance. This SIV infection model using 90-120-Ia-positive macaques would be useful for analysis of the determinants for sequential epitope mutation selection, contributing to our understanding of virus-host CD8 + T-cell interaction in HIV infection., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: HIV-1 circulating recombinant form (CRF) 01_AE is the second major subtype in Japan. Our previous study indicated that CRF01_AE was predominantly circulating in heterosexuals/injecting drug users (IDUs). With implications of increased CRF01_AE infections among men who have sex with men (MSM), this study sought to investigate whether the transmission dynamics of CRF01_AE infections in Japan have changed., Methods: Sequences from 8032 newly diagnosed HIV-1-infected individuals were analysed. For 614 (7.6%) of CRF01_AE cases, clusters were identified and categorised by transmission risks. Median times to the most recent common ancestors (tMRCA) were estimated., Results: The individuals were predominantly Japanese (64%) and male (72%). MSM became the predominant transmission risk from 2014. Thirty transmission clusters (TCs) and 48 pairs, including 40% of individuals, were identified. MSM were approximately five times more likely to be in a TC compared to heterosexuals, and were the major contributors to TCs. tMRCA data suggest that MSM TCs emerged from 1996 and became predominant around 2000., Conclusions: CRF01_AE has spread among MSM, with frequent and continuous cluster formations, and MSM has become the predominant transmission risk. Our study suggested that CRF01_AE transmission has shifted from heterosexuals/IDUs to MSM. Prevention measures targeting key populations should be considered for controlling CRF01_AE spread., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Cumulative studies on human immunodeficiency virus (HIV)-infected individuals have shown association of major histocompatibility complex class I (MHC-I) polymorphisms with lower viral load and delayed AIDS progression, suggesting that HIV replication can be controlled by potent CD8 + T-cell responses. We have previously established an AIDS model of simian immunodeficiency virus (SIV) infection in Burmese rhesus macaques and found a potent CD8 + T cell targeting the Mamu-A1*065:01-restricted Gag 241-249 epitope, which is located in a region corresponding to the HIV Gag 240-249 TW10 epitope restricted by a protective MHC-I allele, HLA-B*57. In the present study, we determined a T cell receptor (TCR) of this Gag 241-249 epitope-specific CD8 + T cell. cDNA clones encoding TCR-α and TCR-β chains were obtained from a Gag 241-249 -specific CD8 + T-cell clone. Coexpression of these TCR-α and TCR-β cDNAs resulted in reconstitution of a functional TCR specifically detected by Gag 241-249 epitope-Mamu-A1*065:01 tetramer. Two of three previously-reported CD8 + T-cell escape mutations reduced binding affinity of Gag 241-249 peptide to Mamu-A1*065:01 but the remaining one not. This is consistent with the data obtained by molecular modeling of the epitope-MHC-I complex and TCR. These results would contribute to understanding how viral CD8 + T-cell escape mutations are selected under structural constraint of viral proteins., (Copyright © 2019 Elsevier Inc. All rights reserved.)

In human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infections, host major histocompatibility complex class I (MHC-I) genotypes have a great impact on viral replication and MHC-I-associated viral genome mutations are selected under CD8 + T-cell pressure. Association of MHC-I genotypes with HIV/SIV control has been investigated at MHC-I allele levels but not fully at haplotype levels. We previously established groups of rhesus macaques sharing individual MHC-I haplotypes. In the present study, we compared viral genome diversification after SIV infection in macaques possessing a protective MHC-I haplotype, 90-010-Id, with those possessing a non-protective MHC-I haplotype, 90-010-Ie. These two MHC-I haplotypes are associated with immunodominant CD8 + T-cell responses targeting similar regions of viral Nef antigen. Analyses of viral genome sequences and antigen-specific T-cell responses showed four and two candidates of viral CD8 + T-cell targets associated with 90-010-Id and 90-010-Ie, respectively, in addition to the Nef targets. In these CD8 + T-cell target regions, higher numbers of mutations were detected at the setpoint after SIV infection in macaques possessing 90-010-Id than those possessing 90-010-Ie. These results indicate higher selective pressure on overall CD8 + T-cell targets associated with the protective MHC-I haplotype, suggesting a pattern of HIV/SIV control by multiple target-specific CD8 + T-cell responses., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Numbers of HLA-associated polymorphisms have been reported on HIV-1 subtypes B and C, but few on other subtypes. Here, we analyzed HLA-associated gag and nef polymorphisms in HIV-1 subtype A/E prevalent in Vietnam. We determined HLA-A, B and C genotypes in 179 HIV-1-infected Vietnamese by next generation sequencing and analyzed proviral genome sequences in 144 of them, showing that 142 of the 144 were subtype A/E. Analysis revealed HLA-associated subtype A/E gag and nef polymorphisms at nineteen residues including those newly determined. Accumulation of these data would contribute to our understanding of HIV-1 subtype A/E and host immune interaction., (Copyright © 2018 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)

Current anti-hepatitis B virus (HBV) agents have limited effect in curing HBV infection, and thus novel anti-HBV agents with different modes of action are in demand. In this study, we applied AlphaScreen assay to high-throughput screening of small molecules inhibiting the interaction between HBV large surface antigen (LHBs) and the HBV entry receptor, sodium taurocholate cotransporting polypeptide (NTCP). From the chemical screening, we identified that rapamycin, an immunosuppressant, strongly inhibited the LHBs-NTCP interaction. Rapamycin inhibited hepatocyte infection with HBV without significant cytotoxicity. This activity was due to impaired attachment of the LHBs preS1 domain to cell surface. Pretreatment of target cells with rapamycin remarkably reduced their susceptibility to preS1 attachment, while rapamycin pretreatment to preS1 did not affect its attachment activity, suggesting that rapamycin targets the host side. In support of this, a surface plasmon resonance analysis showed a direct interaction of rapamycin with NTCP. Consistently, rapamycin also prevented hepatitis D virus infection, whose entry into cells is also mediated by NTCP. We also identified two rapamycin derivatives, everolimus and temsirolimus, which possessed higher anti-HBV potencies than rapamycin. Thus, this is the first report for application of AlphaScreen technology that monitors a viral envelope-receptor interaction to identify viral entry inhibitors., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Virus-specific CD8(+) T-cell responses are crucial for the control of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) replication. Multiple studies on HIV-infected individuals and SIV-infected macaques have indicated association of several major histocompatibility complex class I (MHC-I) genotypes with lower viral loads and delayed AIDS progression. Understanding of the viral control mechanism associated with these MHC-I genotypes would contribute to the development of intervention strategy for HIV control. We have previously reported a rhesus MHC-I haplotype, 90-120-Ia, associated with lower viral loads after SIVmac239 infection. Gag206-216 and Gag241-249 epitope-specific CD8(+) T-cell responses have been shown to play a central role in the reduction of viral loads, whereas the effect of Nef-specific CD8(+) T-cell responses induced in all the 90-120-Ia(+) macaques on SIV replication remains unknown. Here, we identified three CD8(+) T-cell epitopes, Nef9-19, Nef89-97, and Nef193-203, associated with 90-120-Ia. Nef9-19 and Nef193-203 epitope-specific CD8(+) T-cell responses frequently selected for mutations resulting in viral escape from recognition by these CD8(+) T cells, indicating that these CD8(+) T cells exert strong suppressive pressure on SIV replication. Results would be useful for elucidation of the viral control mechanism associated with 90-120-Ia., (Copyright © 2014 Elsevier Inc. All rights reserved.)

IL-21 signaling is important for T cell and B cell-mediated clearance of chronic viral infections. While non-cognate follicular helper CD4+ T cells (TFH) are indicated to be pivotal in providing IL-21-mediated help to activated B cells within germinal centers, how this signaling may be disrupted in early AIDS virus infection is not clear. In this study, we assessed the lineage and kinetics of peripheral blood IL-21-producing CD4+ T cells in primary simian immunodeficiency virus (SIV) infection of rhesus macaques. After SIV challenge, antigen-nonspecific IL-21 production was observed in Th1, Th2 and Th17 cells with Th1 dominance. While IL-21+ Th2 and IL-21+ Th17 showed variable kinetics, an increase in total IL-21+ CD4+ T cells and IL-21+ Th1 from week 3 to week 8 was observed, preceding plasma SIV-specific IgG development from week 5 to week 12. SIV Gag-specific IL-21+ CD4+ T cells detectable at week 2 were decreased in frequencies at week 5. Results imply that kinetics of IL-21+ CD4+ T cells comprised of multiple lineages, potentially targeted by SIV with a bias of existing frequencies during their precursor stage, associate with availability of cooperative B-cell help provided through a proportionate precursor pool developing into TFH and subsequent anti-SIV antibody responses., (Copyright © 2013 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)

HIV-1 is strictly adapted to humans, and cause disease-inducing persistent infection only in humans. We have generated a series of macaque-tropic HIV-1 (HIV-1mt) to establish non-human primate models for basic and clinical studies. HIV-1mt clones available to date grow poorly in macaque cells relative to SIVmac239. In this study, viral adaptive mutation in macaque cells, G114E in capsid (CA) helix 6 of HIV-1mt, that enhances viral replication was identified. Computer-assisted structural analysis predicted that another Q110D mutation in CA helix 6 would also increase viral growth potential. A new proviral construct MN4Rh-3 carrying CA-Q110D exhibited exquisitely enhanced growth property specifically in macaque cells. Susceptibility of MN4Rh-3 to macaque TRIM5α/TRIMCyp proteins was examined by their expression systems. HIV-1mt clones so far constructed already completely evaded TRIMCyp restriction, and further enhancement of TRIMCyp resistance by Q110D was not observed. In addition, Q110D did not contribute to evasion from TRIM5α restriction. However, the single-cycle infectivity of MN4Rh-3 in macaque cells was enhanced relative to the other HIV-1mt clones. Our results here indicate that CA-Q110D accelerates viral growth in macaque cells irrelevant to TRIM5 proteins restriction., (Copyright © 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)

Induction of durable cellular immune responses by vaccination is an important strategy for the control of persistent pathogen infection. Viral vectors are promising vaccine tools for eliciting antigen-specific T-cell responses. Repeated vaccination may contribute to durable memory T-cell induction, but anti-vector antibodies could be an obstacle to its efficacy. We previously developed a Sendai virus (SeV) vector vaccine and showed the potential of this vector for efficient T-cell induction in macaques. Here, we examined whether repeated SeV vector vaccination with short intervals can enhance antigen-specific CD8(+) T-cell responses. Four rhesus macaques possessing the MHC-I haplotype 90-120-Ia were immunized three times with intervals of three weeks. For the vaccination, we used replication-defective F-deleted SeV vectors inducing CD8(+) T-cell responses specific for simian immunodeficiency virus Gag(206-216) and Gag(241-249), which are dominant epitopes restricted by 90-120-Ia-derived MHC-I molecules. All four animals showed higher Gag(206-216)-specific and Gag(241-249)-specific CD8(+) T-cell responses after the third vaccination than those after the first vaccination, indicating enhancement of antigen-specific CD8(+) T-cell responses by the second/third SeV vector vaccination even with short intervals. These results suggest that repeated SeV vector vaccination can contribute to induction of efficient and durable T-cell responses., (Copyright © 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)

Cytotoxic T lymphocyte (CTL) responses are crucial for the control of human and simian immunodeficiency virus (HIV and SIV) replication. A promising AIDS vaccine strategy is to induce CTL memory resulting in more effective CTL responses post-viral exposure compared to those in natural HIV infections. We previously developed a CTL-inducing vaccine and showed SIV control in some vaccinated rhesus macaques. These vaccine-based SIV controllers elicited vaccine antigen-specific CTL responses dominantly in the acute phase post-challenge. Here, we examined CTL responses post-challenge in those vaccinated animals that failed to control SIV replication. Unvaccinated rhesus macaques possessing the major histocompatibility complex class I haplotype 90-088-Ij dominantly elicited SIV non-Gag antigen-specific CTL responses after SIV challenge, while those induced with Gag-specific CTL memory by prophylactic vaccination failed to control SIV replication with dominant Gag-specific CTL responses in the acute phase, indicating dominant induction of vaccine antigen-specific CTL responses post-challenge even in non-controllers. Further analysis suggested that prophylactic vaccination results in dominant induction of vaccine antigen-specific CTL responses post-viral exposure but delays SIV non-vaccine antigen-specific CTL responses. These results imply a significant influence of prophylactic vaccination on CTL immunodominance post-viral exposure, providing insights into antigen design in development of a CTL-inducing AIDS vaccine., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Human immunodeficiency virus type 1 (HIV-1) hardly replicates in Old World monkeys. Recently, a mutant HIV-1 clone, NL-DT5R, in which a small part of gag and the entire vif gene are replaced with SIVmac239-derived ones, was shown to be able to replicate in pigtail monkeys but not in rhesus monkeys (RM). In the present study, we found that a modified monkey-tropic HIV-1 (HIV-1mt), MN4-5S, acquired the ability to replicate efficiently in cynomolgus monkeys as compared with the NL-DT5R, while neither NL-DT5R nor MN4-5S replicated in RM cells. These results suggest that multiple determinants may be involved in the restriction of HIV-1 replication in macaques, depending on the species of macaques. The new HIV-1mt clone will be useful for studying molecular mechanisms by which anti-viral host factors regulate HIV-1 replication in macaques., (Copyright © 2010 Institut Pasteur. Published by Elsevier SAS. All rights reserved.)

Recombinant viral vectors are promising vaccine tools for eliciting potent cellular immune responses against immunodeficiency virus infection, but pre-existing anti-vector antibodies can be an obstacle to their clinical use in humans. We have previously vaccinated rhesus macaques with a recombinant Sendai virus (SeV) vector twice at an interval of more than 1 year and have shown efficient antigen-specific T-cell induction by the second as well as the first vaccination. Here, we have established the method for measurement of SeV-specific neutralizing titers and have found efficient SeV-specific neutralizing antibody responses just before the second SeV vaccination in these macaques. This suggests the feasibility of inducing antigen-specific T-cell responses by SeV vaccination even in the host with pre-existing anti-SeV neutralizing antibodies.

A current promising AIDS vaccine strategy is to elicit CD8(+) cytotoxic T lymphocyte (CTL) responses that broadly recognize highly-diversified HIVs. In our previous vaccine trial eliciting simian immunodeficiency virus (SIV) mac239 Gag-specific CTL responses, a group of Burmese rhesus macaques possessing a major histocompatibility complex haplotype 90-120-Ia have shown vaccine-based viral control against a homologous SIVmac239 challenge. Vaccine-induced Gag(206-216) epitope-specific CTL responses exerted strong selective pressure on the virus in this control. Here, we have evaluated in vivo efficacy of vaccine-induced Gag(206-216)-specific CTL responses in two 90-120-Ia-positive macaques against challenge with a heterologous SIVsmE543-3 that has the same Gag(206-216) epitope sequence with SIVmac239. Despite efficient Gag(206-216)-specific CTL induction by vaccination, both vaccinees failed to control SIVsmE543-3 replication and neither of them showed mutations within the Gag(206-216) epitope. Further analysis indicated that Gag(206-216)-specific CTLs failed to show responses against SIVsmE543-3 infection due to a change from aspartate to glutamate at Gag residue 205 immediately preceding the amino terminus of Gag(206-216) epitope. Our results suggest that even vaccine-induced CTL efficacy can be abrogated by a single amino acid change in viral epitope flanking region, underlining the influence of viral epitope flanking sequences on CTL-based AIDS vaccine efficacy.

Fv-4 is a mouse gene that confers resistance against ecotropic murine leukemia virus (MLV) infection on mice. While receptor interference by the Fv-4 env gene product, Fv-4 Env, that can bind to the ecotropic MLV receptor has been shown to play an important role in the resistance, other mechanisms have also been suggested because it confers extremely efficient, complete resistance in vivo. Here, we have examined the effect of Fv-4 Env on infectious MLV production. Infectious MLV titers in supernatants obtained after transfection with a Friend MLV (FMLV) Env-expressing plasmid from MLV gag-pol producer cells harboring a retroviral vector were largely reduced by coexpression of Fv-4 Env. Syncytia formation mediated by R-peptide-deleted FMLV Env in NIH 3T3 cells was impaired by Fv-4 Env coexpression. Similarly, Fv-4 Env inhibited infectious amphotropic MLV production and syncytia formation mediated by R-peptide-deleted amphotropic MLV Env. Immunoprecipitation analysis revealed interaction of Fv-4 Env with amphotropic MLV Env as well as FMLV Env. These results indicate that Fv-4 Env inhibits infectious ecotropic and amphotropic MLV production by exerting dominant negative effect on MLV Env, suggesting contribution of this inhibitory effect to the resistance against ecotropic MLV infection in Fv-4-expressing mice.