Treatment of HPV-Related Uterine Cervical Cancer with a Third-Generation Oncolytic Herpes Simplex Virus in Combination with an Immune Checkpoint Inhibitor.

Cervical cancer is one of the most common cancers in women. The development of new therapies with immune checkpoint inhibitors (ICIs) is being investigated for cervical cancer; however, their efficacy is not currently sufficient. Oncolytic virus therapy can increase tumor immunogenicity and enhance the antitumor effect of ICIs. In this report, the therapeutic potential of a triple-mutated oncolytic herpes virus (T-01) with an ICI for human papillomavirus (HPV)-related cervical cancer was evaluated using a bilateral syngeneic murine model. The efficacy of intratumoral (i.t.) administration with T-01 and subcutaneous (s.c.) administration of anti-programmed cell death ligand 1 (PD-L1) antibody (Ab) was equivalent to that of anti-PD-L1 Ab alone on the T-01-injected side. Moreover, combination therapy had no significant antitumor effect compared to monotherapy on the T-01-non-injected side. Combination therapy significantly increased the number of tumor specific T cells in the tumor. While T-01 could not be isolated from tumors receiving combination therapy, it could be isolated following T-01 monotherapy. Furthermore, T-01 had a cytotoxic effect on stimulated T cells. These results suggest that T-01 and anti-PD-L1 Ab partially counteract and therefore concomitant administration should be considered with caution.

The efficacy of a third-generation oncolytic herpes simplex viral therapy for an HPV-related uterine cervical cancer model.

PURPOSE: Cervical cancer is the fourth most common cancer in women and the seventh most common of all human cancers. Development of new treatments is mandatory to improve the outcome of this disease. Replication-selective oncolytic herpes simplex viruses (HSVs) have emerged as a new platform for cancer therapy. The therapeutic potential of a triple-mutated oncolytic HSV (T-01) for human papillomavirus (HPV)-related cervical cancer was evaluated with immunodeficient and immune-complete models. METHODS: (1) The in vitro efficacy of T-01 on human cervical cancer cell lines, TC-1, HeLa, CaSki, and SKG IIIa was evaluated. (2) The in vivo efficacy of T-01 was examined in human HeLa xenograft and TC-1 syngeneic models of human cervical cancer. After flank tumors reached 5 mm in diameter, the first intratumoral (i.t.) administration of T-01 was performed. Intratumoral administration of T-01 was performed with a 5 day interval a total of 6 times. RESULTS: In the in vitro study, T-01 was highly cytotoxic for all cell lines (48 h after infection with T-01 at 1 × 105 PFU, T-01 killing HeLa: 67.5%, Caski: 62.8%, SKG IIIa: 43.2%). Furthermore, in the human HeLa xenograft and TC-1 syngeneic models, T-01 resulted in a significant reduction of tumor growth. In addition, tumor-bearing mice treated with T-01 showed significantly increased numbers of CD8 + T-cells precursors than the control mice (p = 0.03). CONCLUSIONS: These results demonstrate that T-01 has cytotoxic efficacy and inhibited against HPV-related cervical cancer cells. These findings indicate that T-01 has therapeutic potential for HPV-related cervical cancer.

Critical micelle concentration and particle size determine adjuvanticity of cyclic lipopeptides.

Cyclic lipopeptides such as surfactin and polymyxin have potent mucosal adjuvant properties. Cyclic lipopeptides are tensioactive compounds but the relationship between adjuvanticity and surface activity is unknown. Here, we show that the critical micelle concentration (cmc) of surfactant and particle size of the surfactant-protein complex are important determinants of cyclic lipopeptide adjuvanticity. We found that the diameter of cyclic lipopeptide-ovalbumin (OVA) complex particles was significantly larger than that in the solutions of OVA alone at cyclic lipopeptide concentrations above the cmc. OVA-specific antibody titers in mice immunized intranasally with OVA and a cyclic lipopeptide at concentrations above its cmc were significantly higher than those in mice immunized with OVA plus the same dose of the cyclic lipopeptide but administered with formulations in which cyclic lipopeptide concentration was below the cmc. Thus, the concentration of the cyclic lipopeptide in the formulation at immunization, but not its overall dose, was critical for its adjuvanticity. Furthermore, two types of aggregates, the cyclic lipopeptide simplex micelles and the cyclic lipopeptide-OVA complex micelles, were found in formulations with SF concentrations above its cmc. Degranulation of mast cells exposed to SF simplex micelles was more pronounced when SF concentration was above the cmc. In conclusion, our study showed that surface activity properties, such as the cmc and the size of surfactant-protein complex contribute to the adjuvanticity of cyclic lipopeptides. Our study proposes a novel idea that cmc is a key parameter for tensioactive adjuvants. This article is protected by copyright. All rights reserved.

Inhibition of Aurora Kinase A Synergistically Enhances Cytotoxicity in Ovarian Clear Cell Carcinoma Cell Lines Induced by Cisplatin: A Potential Treatment Strategy.

OBJECTIVE: This study aims to clarify the incidence of Aurora kinase A (Aurora-A) protein expression and its correlation with clinical parameters in ovarian clear cell carcinoma (OCCC) tumor tissues. In addition, we assessed the efficacy of ENMD-2076, a novel selective Aurora-A inhibitor, in combination with chemotherapeutic agents for the treatment of OCCC. METHODS/MATERIALS: Aurora-A protein expression was determined by immunohistochemical staining of OCCC specimens from 56 patients to evaluate its correlation with clinical outcomes in OCCC. In the in vitro study, 6 OCCC cell lines were exposed to ENMD-2076 in combination with cisplatin, SN38, doxorubicin, or paclitaxel, and cell proliferation, cell cycle distribution, and apoptosis were assessed. RESULTS: The 5-year survival rates of International Federation of Gynecology and Obstetrics stages IC3 to IV patients with intermediate or strong Aurora-A expression were significantly lower than those of patients with negative or weak Aurora-A expression. Increased Aurora-A expression was associated with significantly worse overall survival of International Federation of Gynecology and Obstetrics stages IC3 to IV patients (21% vs 77%). Multivariate analysis revealed that Aurora-A expression was an independent prognostic factor for stages IC3 to IV OCCC patients. Furthermore, synergistic effects were observed with ENMD-2076 in combination with cisplatin or SN-38 in 4 of the 6 tested cell lines. ENMD-2076 dramatically enhanced apoptosis and cell cycle arrest at the G2/M phase induced by cisplatin. CONCLUSIONS: Aurora-A is a promising biomarker that is predictive of patient outcomes and a potential target for OCCC. The results suggested that chemotherapy, including ENMD-2076 in combination with cisplatin, is a potential treatment modality for patients with OCCC.

Suitability of Polymyxin B as a Mucosal Adjuvant for Intranasal Influenza and COVID-19 Vaccines.

Polymyxin B (PMB) is an antibiotic that exhibits mucosal adjuvanticity for ovalbumin (OVA), which enhances the immune response in the mucosal compartments of mice. Frequent breakthrough infections of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants indicate that the IgA antibody levels elicited by the mRNA vaccines in the mucosal tissues were insufficient for the prophylaxis of this infection. It remains unknown whether PMB exhibits mucosal adjuvanticity for antigens other than OVA. This study investigated the adjuvanticity of PMB for the virus proteins, hemagglutinin (HA) of influenza A virus, and the S1 subunit and S protein of SARS-CoV-2. BALB/c mice immunized either intranasally or subcutaneously with these antigens alone or in combination with PMB were examined, and the antigen-specific antibodies were quantified. PMB substantially increased the production of antigen-specific IgA antibodies in mucosal secretions and IgG antibodies in plasma, indicating its adjuvanticity for both HA and S proteins. This study also revealed that the PMB-virus antigen complex diameter is crucial for the induction of mucosal immunity. No detrimental effects were observed on the nasal mucosa or olfactory bulb. These findings highlight the potential of PMB as a safe candidate for intranasal vaccination to induce mucosal IgA antibodies for prophylaxis against mucosally transmitted infections.

The relationship between the chemical structure, physicochemical properties, and mucosal adjuvanticity of sugar-based surfactants.

The relationship between the chemical structure, physicochemical properties, and mucosal adjuvanticity of sugar-based surfactants (SBSs) has not been sufficiently elucidated. Thus, in the present study, we systematically analyzed 11 SBSs for mucosal adjuvanticity. Ovalbumin (OVA)-specific antibody titers were measured in mice immunized intranasally with OVA plus SBS. We found that four SBSs (trehalose monododecanoate, sucrose monododecanoate, n-dodecyl-α-d-maltopyranoside, and n-dodecyl-ß-d-maltopyranoside) exhibited the most potent adjuvanticity. We identified the following associations between chemical structure and adjuvanticity: 1) OVA-specific antibody titer increased with an increasing number of carbon atoms in the alkyl chain; 2) the adjuvanticity was not affected by the type of sugar or bond between the sugar and alkyl chain; and 3) SBSs with rigid structures exhibited less adjuvanticity. The relationship between physicochemical properties and adjuvanticity was as follows: 1) SBSs exhibited adjuvanticity above the critical micelle concentration and 2) in the SBSs with potent adjuvanticity, the diameter of the SBS-OVA complex was 70-75 nm. Our study indicates evidence for the direct involvement of chemical structure and physicochemical properties in determining adjuvanticity in SBSs.

A mouse monoclonal antibody against influenza C virus attenuates acetaminophen-induced liver injury in mice.

Molecular mimicry is one of the main processes for producing autoantibodies during infections. Although some autoantibodies are associated with autoimmune diseases, the functions of many autoantibodies remain unknown. Previously, we reported that S16, a mouse (BALB/c) monoclonal antibody against the hemagglutinin-esterase fusion glycoprotein of influenza C virus, recognizes host proteins in some species of animals, but we could not succeed in identifying the proteins. In the present study, we found that S16 cross-reacted with acetyl-CoA acyltransferase 2 (ACAA2), which is expressed in the livers of BALB/c mice. ACAA2 was released into the serum after acetaminophen (APAP) administration, and its serum level correlated with serum alanine aminotransferase (ALT) activity. Furthermore, we observed that S16 injected into mice with APAP-induced hepatic injury prompted the formation of an immune complex between S16 and ACAA2 in the serum. The levels of serum ALT (p < 0.01) and necrotic areas in the liver (p < 0.01) were reduced in the S16-injected mice. These results suggest that S16 may have a mitigation function in response to APAP-induced hepatotoxicity. This study shows the therapeutic function of an autoantibody and suggests that an antibody against extracellular ACAA2 might be a candidate for treating APAP-induced hepatic injury.

A systematic assessment of the relationship between synthetic surfactants and mucosal adjuvanticity.

Intranasal immunization with surfactants as vaccine adjuvants enhances protective immunity against invasive mucosal pathogens. However, the effects of surfactants and their adjuvanticity on mucosal immune responses remain unclear. Comparison of the mucosal adjuvanticity of 20 water-soluble surfactants from the four classes based upon the polarity composition of the hydrophilic headgroup revealed that the order of mucosal adjuvanticity was as follows: amphoteric > nonionic > cationic > anionic. Within the same class, each surfactant displayed different adjuvanticity values. Analysis of the diameter and ζ-potential of amphoteric surfactant-OVA complexes and their surface physicochemical properties revealed that the diameter was approximately 100 nm, which is considered suitable for immune induction, and that the ζ-potential of the anionic surfactant-OVA complexes was exceedingly negative. The increase in the number of carbon atoms in the hydrophobic tailgroups of the amphoteric surfactant resulted in an increase in the OVA-specific Ab titers. Our findings demonstrate that amphoteric surfactants exhibit potent mucosal adjuvanticity and highlight the importance of the number of carbon atoms in the tailgroups and the diameter and ζ-potential of the complexes when designing mucosal adjuvants.

[HIV infected pregnant women in Japan and prevention of mother-to-child transmission].

By the investigation of our study group 595 HIV infected pregnant women have been confirmed in Japan since 1984. In recent years, around 40 pregnant women a year were diagnosed as HIV positive. These HIV infected pregnant women were not concerned with a value of CD4 and received antiretroviral therapy such as zidovudine (AZT) monotherapy or highly active antiretroviral therapy (HAART) starting from the second trimester of pregnancy. According to recommendations and current data, cesarean delivery before the onset of labor is performed around 37 weeks of pregnancy and prophylactic AZT syrups are given to infants starting 8-12 hrs after birth for 6 weeks. These preventive managements such as antiretroviral therapy, elective cesarean delivery and formula feeding significantly reduced mother-to-child transmission (MTCT) of HIV. The transmission rate of HIV fell to 0.5% in Japan, but the problem of the teratogenicity of antiretroviral drugs remain unclear. Further studies are needed.

Optimization of trypsins for influenza A/H1N1 virus replication in MDCK SI-6 cells, a novel MDCK cell line.

A cell-based vaccine production method for influenza virus may be an effective and more rapid alternative to egg-based systems. For high-yield virus production, the effect of bovine, porcine, fungal, and recombinant trypsins on influenza A/H1N1 virus replication in MDCK SI-6 cells (SI-6 cells), a novel MDCK cell line developed by our research group, was examined. SI-6 cells infected with influenza A/H1N1 virus were incubated in the presence of four trypsin types at various concentrations, and virus yields in the culture medium were evaluated by a hemagglutination (HA) assay. Virus growth was most efficient in the presence of bovine and porcine trypsins. An analysis of the optimized concentration and definitive HA titer of each trypsin by Gaussian distribution revealed that comparable high virus yields (166.1 and 164.2 HAU/50µl) were obtained at the optimized concentrations of bovine (0.4µg/ml) and porcine (2.1µg/ml) trypsins, respectively, the yields of which were significantly higher than that of fungal and recombinant trypsins. We conclude that bovine and porcine trypsins are suitable for influenza A/H1N1 virus replication in SI-6 cells. This result complements our previous study and suggests the possible application of SI-6 cells to the development of cell-based influenza vaccines.

Mast cells partially contribute to mucosal adjuvanticity of surfactin in mice.

INTRODUCTION: Surfactin (SF) is a cyclic lipopeptide that has potent mucosal adjuvant properties. However, immunological mechanisms of SF adjuvant action have not yet been elucidated. As some cyclic lipopeptides, such as polymyxin, can stimulate histamine release from mast cells, we hypothesized that mast cell activation is critical for SF adjuvanticity. METHODS/RESULTS: We observed that following intranasal immunization with ovalbumin (OVA) plus SF, the titers of the OVA-specific antibody (Ab) in the mucosal secretions and plasma of mast cell-deficient mice were significantly lower than those in congenic normal mice, although OVA-specific Ab did not entirely disappear from mast cell-deficient mice. SF induced degranulation of mast cells and release of histamine in vitro. To investigate whether SF stimulated mast cells in vivo, we measured body temperature of mice immunized intranasally with OVA plus SF because histamine level affects body temperature. Following immunizations, body temperature of immunized congenic normal mice transiently decreased, whereas body temperature of mast cell-deficient mice did not change. Plasma levels of OVA-specific IgE Ab were not significantly different in mast cell-deficient and congenic normal mice. These findings suggest that SF directly affected mast cells in an IgE Ab-independent fashion. Furthermore, we analyzed the effects of SF on MC/9 mast cells cultured in vitro. MC/9 cells stimulated by SF released not only histamine but also leukotriene B4 and prostaglandin D2 . Moreover, SF up-regulated mRNA expression levels of Tnf, Ccr5, and Il4 genes in mast cells. These cytokines may play a facilitating role in OVA-specific immune responses in mice. CONCLUSION: Overall, our results showed that mast cell activation partially mediated SF adjuvanticity.

Establishment of a cell model of X-linked sideroblastic anemia using genome editing.

ALAS2 gene mutations cause X-linked sideroblastic anemia. The presence of ring sideroblasts in a patient's bone marrow is the hallmark of sideroblastic anemia, but the precise mechanisms underlying sideroblast formation are largely unknown. Using a genome-editing system, a mutation was introduced in the erythroid-specific enhancer of the ALAS2 gene in HUDEP2 cells, which were derived from human umbilical stem cells and can produce erythrocytes. The established cell line, termed HA2low, expressed less ALAS2 mRNA than did wild-type cells, even after erythroid differentiation. Although the mRNA expression of α-globin, ß-globin, and the mitochondrial iron importer mitoferrin-1 was induced similarly in wild-type and HA2low cells, hemoglobinization of differentiated cells was limited in HA2low cells compared with wild-type cells. Importantly, Prussian blue staining revealed that approximately one-third of differentiated HA2low cells exhibited intracellular iron deposition and these cells looked like ring sideroblasts. Electron microscopy confirmed that the mitochondria in HA2low cells contained high-density deposits that might contain iron. Ring sideroblastic cells appeared among HA2low cells only after differentiation, whereas the induced expression of mitochondrial ferritin was observed in both cell types during differentiation. These results suggest that the induction of mitochondrial ferritin expression might be essential for, but not the primary cause of, ring sideroblast formation. Our results also suggest that the insufficient supply of protoporphyrin IX due to ALAS2 deficiency in combination with increased iron import into mitochondria during erythroid differentiation results in the formation of ring sideroblasts. Furthermore, HA2low cells are a useful tool for characterizing ring sideroblasts in vitro.

Analysis of the beta-propiolactone sensitivity and optimization of inactivation methods for human influenza H3N2 virus.

Beta-propiolactone (BPL) is used as an inactivating reagent for influenza virus in a number of countries. However, the treatment of viruses with BPL occasionally results in a decrease in the hemagglutinin (HA) titer, which complicates vaccine development. In the present study, we examined the biological and biochemical characteristics of human H1N1 and H3N2 viruses treated with BPL, and developed an inactivation method for BPL-sensitive viruses. A significant decrease in HA titer was detected in the H3N2 viruses examined. The decrease in the pH of the virus fluid was not associated with the decreased HA titer, indicating that the decrease in HA titer for the H3N2 virus is the result of the direct effect of BPL. Excessive modification of M1 by BPL and loss of virion diameter were observed in 0.1% BPL-treated H3N2 virus. Taken together, these results suggest that the BPL sensitivity of H3N2 virus results from disruption of the virion. By contrast, the H3N2 virus was successfully inactivated by 0.02% BPL without a significant decrease in the HA titer or disruption of virion structure. Furthermore, we found that the 0.02% BPL in the virion preparation was hydrolyzed successfully by incubation at 37°C for 7h. Thus, mild treatment with a low concentration of BPL enabled us to inactivate the H3N2 virus.

Polymyxins as novel and safe mucosal adjuvants to induce humoral immune responses in mice.

There is currently an urgent need to develop safe and effective adjuvants for enhancing vaccine-induced antigen-specific immune responses. We demonstrate here that intranasal immunization with clinically used polypeptide antibiotics, polymyxin B (PMB) and colistin (CL), along with ovalbumin (OVA), increases OVA-specific humoral immune responses in a dose-dependently manner at both mucosal and systemic compartments. Enhanced immunity by boosting was found to persist during 8 months of observation. Moreover, mice intranasally immunized with OVA plus various doses of PMB or CL showed neither inflammatory responses in the nasal cavity and olfactory bulbs nor renal damages, compared to those given OVA alone. These data suggest that polymyxins may serve as novel and safe mucosal adjuvants to induce humoral immune responses. The polymyxin adjuvanticity was found to be independent of endotoxins liberated by its bactericidal activity, as indicated by similar enhancing effects of PMB in lipopolysaccharide (LPS)-hyporesponsive and LPS-susceptible mice. However, despite the presence of preexisting anti-PMB antibodies, we observed no reduction in the adjuvant function of polymyxins when they were given intranasally. Furthermore, the titers of OVA-specific Abs in mice intranasally immunized with OVA plus PMB or CL were significantly higher than those in mice administered with polymyxin analogues, such as polymyxin B nonapeptide and colistin methanesulfonate. The levels of released ß-hexosaminidase and histamine in mast cell culture supernatants stimulated by PMB or CL were also significantly higher than those stimulated by their analogues. These results suggest that both the hydrophobic carbon chain and hydrophilic cationic cyclic peptide contribute to the mucosal adjuvanticity of PMB and CL.

Mucosal immune responses in W/W(v) and Sl/Sl(d) mutant mice.

In order to identify potential unanticipated side reactions and immune responses, the evaluation of candidate vaccines should include immunization of the murine model of the disease in question and mutant animals, as well as normal laboratory animals. We employed WBB6F(1)-W/W(v) and WBB6F(1)-Sl/Sl(d) mutant mice, which are genetically mast cell deficient and lack intestinal pacemaker activity due to a severe deficiency in interstitial cells of Cajal. Antigen-specific mucosal and systemic immune responses in the mutant and congenic normal mice were induced by intranasal or intragastric immunization with ovalbumin (OVA) plus cholera toxin as an adjuvant. It was found that the levels of the OVA-specific humoral immune response in the mucosal and systemic tissues of the mutant mice immunized intranasally were roughly equivalent to those of the congenic normal mice. In contrast, the specific humoral immune response in the intragastrically immunized mutant mice was greater than that observed in the congenic normal mice. Unexpectedly, the titers of OVA-specific IgA antibodies and total IgA antibodies in the fecal extracts of both intranasally and intragastrically immunized mutant mice were significantly lower than in those of the congenic normal mice. Although the detailed mechanisms leading to these differences remain unclear, the unexpected immune responses observed in the gastrointestinal tracts of the mice in this study may be related to an abnormality of gastrointestinal motility. Our data therefore suggest that studies using mutant mice and physiological assessments should be carried out during mucosal vaccine development.

Co-administration of cholera toxin and apple polyphenol extract as a novel and safe mucosal adjuvant strategy.

Although native cholera toxin (CT) is an extremely effective adjuvant, its toxicity prevents its use in humans. We report here that apple polyphenol extract (APE), obtained from unripe apples, reduces CT-induced morphological changes and cAMP accumulation. Based upon this finding, we have attempted to design a novel, effective and safe mucosal vaccine by using CT with several dosages of APE as nasal adjuvants. Mice nasally immunized with OVA plus CT and an optimal dosage of APE showed significantly reduced levels of inflammatory responses as well as total and OVA-specific IgE antibodies when compared with mice given without APE. However, levels of both mucosal and systemic OVA-specific antibody responses were maintained. Further, APE significantly down-regulated accumulation of CT in the olfactory nerves and epithelium. In summary, an optimal dosage of APE would take full advantage of mucosal adjuvanticity of native CT without any toxicity for application in humans.

Postinfection passive transfer of KD-247 protects against simian/human immunodeficiency virus-induced CD4+ T-cell loss in macaque lymphoid tissue.

BACKGROUND: Preadministration of high-affinity humanized anti-HIV-1 mAb KD-247 by passive transfer provides sterile protection of monkeys from heterologous chimeric simian/human immunodeficiency virus infection. METHODS: Beginning 1 h, 1 day, or 1 week after simian/human immunodeficiency virus-C2/1 challenge (20 50% tissue culture infective dose), mature, male cynomolgus monkeys received multiple passive transfers of KD-247 (45 mg/kg) on a weekly basis for approximately 2 months. Concentrations and viral loads were measured in peripheral blood, and CD4 T-cell counts were examined in both peripheral blood and various lymphoid tissues. RESULTS: Pharmacokinetic examination revealed similar plasma maintenance levels ranging from 200 to 500 microg/ml of KD-247 in the three groups. One of the six monkeys given KD-247 could not maintain these concentrations, and elicitation of anti-KD-247 idiotype antibody was suggested. All monkeys given KD-247 exhibited striking postinfection protection against both CD4 T-cell loss in various lymphoid tissues and atrophic changes in organs compared with control group animals treated with normal human immunoglobulin G. The KD-247-treated groups were also partially protected against plasma viral load elevation in peripheral blood samples, although the complete protection previously reported with preadministration of this mAb was not achieved. CONCLUSION: Postinfection passive transfer of humanized mAb KD-247 with strong neutralizing capacity against challenged virus simian/human immunodeficiency virus-C2/1 protected CD4 T cells in lymphoid organs.

Anti-V3 humanized antibody KD-247 effectively suppresses ex vivo generation of human immunodeficiency virus type 1 and affords sterile protection of monkeys against a heterologous simian/human immunodeficiency virus infection.

In an accompanying report (Y. Eda, M. Takizawa, T. Murakami, H. Maeda, K. Kimachi, H. Yonemura, S. Koyanagi, K. Shiosaki, H. Higuchi, K. Makizumi, T. Nakashima, K. Osatomi, S. Tokiyoshi, S. Matsushita, N. Yamamoto, and M. Honda, J. Virol. 80:5552-5562, 2006), we discuss our production of a high-affinity humanized monoclonal antibody, KD-247, by sequential immunization with V3 peptides derived from human immunodeficiency virus type 1 (HIV-1) clade B primary isolates. Epitope mapping revealed that KD-247 recognized the Pro-Gly-Arg V3 tip sequence conserved in HIV-1 clade B isolates. In this study, we further demonstrate that in vitro, KD-247 efficiently neutralizes CXCR4- and CCR5-tropic primary HIV-1 clade B and clade B' with matching neutralization sequence motifs but does not neutralize sequence-mismatched clade B and clade E isolates. Monkeys were provided sterile protection against heterologous simian/human immunodeficiency virus challenge by the passive transfer of a single high dose (45 mg per kg of body weight) of KD-247 and afforded partial protection by lower antibody doses (30 and 15 mg per kg). Protective neutralization endpoint titers in plasma at the time of virus challenge were 1:160 in animals passively transferred with a high dose of the antibody. The antiviral efficacy of the antibody was further confirmed by its suppression of the ex vivo generation of primary HIV-1 quasispecies in peripheral blood mononuclear cell cultures from HIV-infected individuals. Therefore, KD-247 promises to be a valuable tool not only as a passive immunization antibody for the prevention of HIV infection but also as an immunotherapy for the suppression of HIV in phenotype-matched HIV-infected individuals.

Vaccination of rhesus macaques with recombinant Mycobacterium bovis bacillus Calmette-Guérin Env V3 elicits neutralizing antibody-mediated protection against simian-human immunodeficiency virus with a homologous but not a heterologous V3 motif.

Although the correlates of vaccine-induced protection against human immunodeficiency virus type 1 (HIV-1) are not fully known, it is presumed that neutralizing antibodies (NAb) play a role in controlling virus infection. In this study, we examined immune responses elicited in rhesus macaques following vaccination with recombinant Mycobacterium bovis bacillus Calmette-Guérin expressing an HIV-1 Env V3 antigen (rBCG Env V3). We also determined the effect of vaccination on protection against challenge with either a simian-human immunodeficiency virus (SHIV-MN) or a highly pathogenic SHIV strain (SHIV-89.6PD). Immunization with rBCG Env V3 elicited significant levels of NAb for the 24 weeks tested that were predominantly HIV-1 type specific. Sera from the immunized macaques neutralized primary HIV-1 isolates in vitro, including HIV-1BZ167/X4, HIV-1SF2/X4, HIV-1CI2/X4, and, to a lesser extent, HIV-1MNp/X4, all of which contain a V3 sequence homologous to that of rBCG Env V3. In contrast, neutralization was not observed against HIV-1SF33/X4, which has a heterologous V3 sequence, nor was it found against primary HIV-1 R5 isolates from either clade A or B. Furthermore, the viral load in the vaccinated macaques was significantly reduced following low-dose challenge with SHIV-MN, and early plasma viremia was markedly decreased after high-dose SHIV-MN challenge. In contrast, replication of pathogenic SHIV-89.6PD was not affected by vaccination in any of the macaques. Thus, we have shown that immunization with an rBCG Env V3 vaccine elicits a strong, type-specific V3 NAb response in rhesus macaques. While this response was not sufficient to provide protection against a pathogenic SHIV challenge, it was able to significantly reduce the viral load in macaques following challenge with a nonpathogenic SHIV. These observations suggest that rBCG vectors have the potential to deliver an appropriate virus immunogen for desirable immune elicitations.