Nano-multilamellar lipid vesicles loaded with a recombinant form of the chikungunya virus E2 protein improve the induction of virus-neutralizing antibodies.

Chikungunya virus (CHIKV) is responsible for a self-limited illness that can evolve into long-lasting painful joint inflammation. In this study, we report a novel experimental CHIKV vaccine formulation of lipid nanoparticles loaded with a recombinant protein derived from the E2 structural protein. This antigen fragment, designated ∆E2.1, maintained the antigenicity of the native viral protein and was specifically recognized by antibodies induced in CHIKV-infected patients. The antigen has been formulated into nanoparticles consisting of nano-multilamellar vesicles (NMVs) combined with the adjuvant monophosphoryl lipid A (MPLA). The vaccine formulation demonstrated a depot effect, leading to controlled antigen release, and induced strong antibody responses significantly higher than in mice immunized with the purified protein combined with the adjuvant. More relevantly, E2-specific antibodies raised in mice immunized with ∆E2.1-loaded NMV-MPLA neutralized CHIKV under in vitro conditions. Taken together, the results demonstrated that the new nanoparticle-based vaccine formulation represents a promising approach for the development of effective anti-CHIKV vaccines.

Tozinameran (BNT162b2) Vaccine: The Journey from Preclinical Research to Clinical Trials and Authorization.

Vaccination development and production was an essential question for the prevention and global control of COVID-19. The strong support from governing authorities such as Operation Warp Speed and robust funding has led to the development and authorization of the tozinameran (BNT162b2) vaccine. The BNT162b2 vaccine is a lipid nanoparticle-encapsulated mRNA that encodes for SARS-CoV-2 spike protein, the main site for neutralizing antibodies. Once it binds with the host cells, the lipid nanoparticles enable the transfer of the RNA, causing S antigens' expression of the SARS-CoV-2, conferring immunity. The vaccine is administered as a 2-dose regime 21 days apart for individuals 16 years and older. Pfizer-BioNTech's BNT162b2 vaccine was the first candidate to receive FDA-Emergency Use Authorization (EUA) on December 11, 2020. During phase 2/3 clinical trials, 95% efficacy was reported among 37,706 participants over the age of 16 who received the BNT162b2 vaccination; additionally, 52% efficacy was noted 12 days following the administration of the first dose of BNT162b2, reflecting early protection of COVID-19. The BNT162b2 vaccine has exhibited 100% efficacy in clinical trials of adolescents between the ages of 12 and 15. Clinical trials in pregnant women and children under the age of 12 are expected to also exhibit promising results. This review article encompasses tozinameran (BNT162b2) vaccine journey, summarizing the BNT162b1 and BNT162b2 vaccines from preclinical studies, clinical trial phases, dosages, immune response, adverse effects, and FDA-EUA.

Impact of the expression system on the immune responses to self-assembling protein nanoparticles (SAPNs) displaying HIV-1 V1V2 loop.

The V1V2 loop of the Env protein is a major target for HIV-1 vaccine development because in multiple studies antibodies to this region correlated with protection. Although SAPNs expressed in E. coli elicited anti-V1V2 antibodies, the Env protein is heavily glycosylated. In this study the technology has been adapted for expression in mammalian cells. SAPNs containing a V1V2 loop from a B-subtype transmitter/founder virus were expressed in E. coli, ExpiCHO, and Expi293 cells. Independent of the expression host, particles were well-formed. All SAPNs raised high titers of V1V2-specific antibodies, however, SAPNE.coli induced a mainly anti-V1 response, while SAPNExpiCHO and SAPNExpi293 induced a predominantly anti-V2 response. In an ADCP assay, sera from animals immunized with the SAPNExpiCHO or SAPNExpi293 induced a significant increase in phagocytic activity. This novel way of producing SAPNs displaying glycosylated epitopes could increase the antibody titer, functional activity, and shift the immune response towards the desired pathway.

Poly-Gamma-Glutamic Acid (γ-PGA)-Based Encapsulation of Adenovirus to Evade Neutralizing Antibodies.

In recent years, there has been an increasing interest in oncolytic adenoviral vectors as an alternative anticancer therapy. The induction of an immune response can be considered as a major limitation of this kind of application. Significant research efforts have been focused on the development of biodegradable polymer poly-gamma-glutamic acid (γ-PGA)-based nanoparticles used as a vector for effective and safe anticancer therapy, owing to their controlled and sustained-release properties, low toxicity, as well as biocompatibility with tissue and cells. This study aimed to introduce a specific destructive and antibody blind polymer-coated viral vector into cancer cells using γ-PGA and chitosan (CH). Adenovirus was successfully encapsulated into the biopolymer particles with an encapsulation efficiency of 92% and particle size of 485 nm using the ionic gelation method. Therapeutic agents or nanoparticles (NPs) that carry therapeutics can be directed specifically to cancerous cells by decorating their surfaces using targeting ligands. Moreover, in vitro neutralizing antibody response against viral capsid proteins can be somewhat reduced by encapsulating adenovirus into γ-PGA-CH NPs, as only 3.1% of the encapsulated adenovirus was detected by anti-adenovirus antibodies in the presented work compared to naked adenoviruses. The results obtained and the unique characteristics of the polymer established in this research could provide a reference for the coating and controlled release of viral vectors used in anticancer therapy.

Impact of immunosuppressive therapy on therapy-neutralizing antibodies in transplanted patients with Fabry disease.

BACKGROUND: Inhibitory antibodies towards enzyme replacement therapy (ERT) are associated with disease progression and poor outcome in affected male patients with lysosomal disorders such as Fabry disease (FD). However, little is known about the impact of immunosuppressive therapy on ERT inhibition in these patients with FD. METHODS: In this retrospective study, we investigated the effect of long-term immunosuppression on ERT inhibition in male patients with FD (n = 26) receiving immunosuppressive therapy due to kidney (n = 24) or heart (n = 2) transplantation. RESULTS: No ERT-naïve transplanted patient (n = 8) developed antibodies within follow-up (80 ±72 months) after ERT initiation. Seven (26.9%) patients were tested ERT inhibition positive prior to transplantation. No de novo ERT inhibition was observed after transplantation (n = 18). In patients treated with high dosages of immunosuppressive medication such as prednisolone, tacrolimus and mycophenolate-mofetil/mycophenolate acid, ERT inhibition decreased after transplantation (n = 12; P = 0.0160). Tapering of immunosuppression (especially prednisolone) seemed to re-increase ERT inhibition (n = 4, median [range]: 16.6 [6.9; 36.9] %; P = 0.0972) over time. One ERT inhibition-positive patient required interventions with steroid therapy and increased doses of tacrolimus, which also lowered ERT inhibition. CONCLUSION: We conclude that the immunosuppressive maintenance therapy after transplantations seems to be sufficient to prevent de novo ERT inhibition in ERT-naïve patients. Intensified high dosages of immunosuppressive drugs are associated with decreased antibody titres and decreased ERT inhibition in affected patients, but did not result in long-term protection. Future studies are needed to establish ERT inhibition-specific immunosuppressive protocols with long-term modulating properties to warrant an improved disease course in ERT inhibition-positive males.

Clinical similarity of the biosimilar ABP 501 compared with adalimumab after single transition: long-term results from a randomized controlled, double-blind, 52-week, phase III trial in patients with moderate-to-severe plaque psoriasis.

BACKGROUND: ABP 501, a U.S.A. Food and Drug Administration- and European Medicines Agency-approved biosimilar, is highly similar to adalimumab in structure, function and pharmacokinetics. OBJECTIVES: To demonstrate similarity in efficacy, safety and immunogenicity of ABP 501 vs. adalimumab for moderate-to-severe plaque psoriasis (clinical trial: NCT01970488). METHODS: Patients were randomized (1 : 1) to receive ABP 501 or adalimumab 40 mg every 2 weeks for 16 weeks. At week 16, patients with ≥ 50% improvement from baseline in Psoriasis Area and Severity Index (PASI) score were eligible to continue to week 52. Patients receiving ABP 501 continued; adalimumab patients were rerandomized (1 : 1) to continue adalimumab or undergo a single transition to ABP 501. Key efficacy assessments included percentage PASI improvement from baseline, PASI responders and mean change in affected body surface area from baseline to weeks 16, 32 and 50. Safety was monitored via adverse events (AEs) and antidrug antibodies (ADAs) were assessed. RESULTS: A total of 308 patients were rerandomized at week 16 (ABP 501/ABP 501, n = 152; adalimumab/adalimumab, n = 79; adalimumab/ABP 501, n = 77). PASI percentage improvements from baseline were similar across groups for weeks 16, 32 and 50 (range: 85·8-88·2%), with no significant differences detected across groups in percentages of PASI 50, 75, 90 and 100 responders. Changes from baseline in percentage body surface area affected were similar across groups and time points. No new safety signals were detected. AEs were balanced between groups. Percentages of patients with binding and neutralizing ADAs were similar across treatments. CONCLUSIONS: ABP 501 and adalimumab have similar clinical efficacy, safety and immunogenicity profiles over 52 weeks, including after single transition, in this patient population.

DNA vaccine molecular adjuvants SP-D-BAFF and SP-D-APRIL enhance anti-gp120 immune response and increase HIV-1 neutralizing antibody titers.

UNLABELLED: Broadly neutralizing antibodies (bNAbs) specific for conserved epitopes on the HIV-1 envelope (Env) are believed to be essential for protection against multiple HIV-1 clades. However, vaccines capable of stimulating the production of bNAbs remain a major challenge. Given that polyreactivity and autoreactivity are considered important characteristics of anti-HIV bNAbs, we designed an HIV vaccine incorporating the molecular adjuvants BAFF (B cell activating factor) and APRIL (a proliferation-inducing ligand) with the potential to facilitate the maturation of polyreactive and autoreactive B cells as well as to enhance the affinity and/or avidity of Env-specific antibodies. We designed recombinant DNA plasmids encoding soluble multitrimers of BAFF and APRIL using surfactant protein D as a scaffold, and we vaccinated mice with these molecular adjuvants using DNA and DNA-protein vaccination strategies. We found that immunization of mice with a DNA vaccine encoding BAFF or APRIL multitrimers, together with interleukin 12 (IL-12) and membrane-bound HIV-1 Env gp140, induced neutralizing antibodies against tier 1 and tier 2 (vaccine strain) viruses. The APRIL-containing vaccine was particularly effective at generating tier 2 neutralizing antibodies following a protein boost. These BAFF and APRIL effects coincided with an enhanced germinal center (GC) reaction, increased anti-gp120 antibody-secreting cells, and increased anti-gp120 functional avidity. Notably, BAFF and APRIL did not cause indiscriminate B cell expansion or an increase in total IgG. We propose that BAFF and APRIL multitrimers are promising molecular adjuvants for vaccines designed to induce bNAbs against HIV-1. IMPORTANCE: Recent identification of antibodies that neutralize most HIV-1 strains has revived hopes and efforts to create novel vaccines that can effectively stimulate HIV-1 neutralizing antibodies. However, the multiple immune evasion properties of HIV have hampered these efforts. These include the instability of the gp120 trimer, the inaccessibility of the conserved sequences, highly variable protein sequences, and the loss of HIV-1-specific antibody-producing cells during development. We have shown previously that tumor necrosis factor (TNF) superfamily ligands, including BAFF and APRIL, can be multitrimerized using the lung protein SP-D (surfactant protein D), enhancing immune responses. Here we show that DNA or DNA-protein vaccines encoding BAFF or APRIL multitrimers, IL-12p70, and membrane-bound HIV-1 Env gp140 induced tier 1 and tier 2 neutralizing antibodies in a mouse model. BAFF and APRIL enhanced the immune reaction, improved antibody binding, and increased the numbers of anti-HIV-1 antibody-secreting cells. Adaptation of this vaccine design may prove useful in designing preventive HIV-1 vaccines for humans.

Animal models for the study of hepatitis C virus infection and related liver disease.

Hepatitis C virus (HCV) causes liver-related death in more than 300,000 people annually. Treatments for patients with chronic HCV are suboptimal, despite the introduction of directly acting antiviral agents. There is no vaccine that prevents HCV infection. Relevant animal models are important for HCV research and development of drugs and vaccines. Chimpanzees are the best model for studies of HCV infection and related innate and adaptive host immune responses. They can be used in immunogenicity and efficacy studies of HCV vaccines. The only small animal models of robust HCV infection are T- and B- cell deficient mice with human chimeric livers. Although these mice cannot be used in studies of adaptive immunity, they have provided new insights into HCV neutralization, interactions between virus and receptors, innate host responses, and therapeutic approaches. Recent progress in developing genetically humanized mice is exciting, but these models only permit studies of specific steps in the HCV life cycle and have limited or no viral replication.

Antidrug Antibodies Against Biological Treatments for Multiple Sclerosis.

The development of antidrug antibodies (ADAs) is a major problem in several recombinant protein therapies used in the treatment of multiple sclerosis (MS). The etiology of ADAs is multifaceted. The predisposition for a breakdown of immune tolerance is probably genetically determined, and many factors may contribute to the immunogenicity, including structural properties, formation of aggregates, and presence of contaminants and impurities from the industrial manufacturing process. ADAs may have a neutralizing capacity and can reduce or abrogate the bioactivity and therapeutic efficacy of the drug and cause safety issues. Interferon (IFN)-ß was the first drug approved for the treatment of MS, and-although it is generally recognized that neutralizing antibodies (NAbs) appear and potentially have a negative effect on therapeutic efficacy-the use of routine measurements of NAbs and the interpretation of the presence of NAbs has been debated at length. NAbs appear after 9-18 months of therapy in up to 40% of patients treated with IFNß, and the frequency and titers of NAbs depend on the IFNß preparation. Although all pivotal clinical trials of approved IFNß products in MS exhibited a detrimental effect of NAbs after prolonged therapy, some subsequent studies did not observe clinical effects from NAbs, which led to the claim that NAbs did not matter. However, it is now largely agreed that persistently high titers of NAbs indicate an abrogation of the biological response and, hence, an absence of therapeutic efficacy, and this observation should lead to a change of therapy. Low and medium titers are ambiguous, and treatment decisions should be guided by determination of in vivo messenger RNA myxovirus resistance protein A induction after IFNß administration and clinical disease activity. During treatment with glatiramer acetate, ADAs occur frequently but do not appear to adversely affect treatment efficacy or result in adverse events. ADAs occur in approximately 5% of patients treated with natalizumab within 6 months of therapy, and persistent NAbs are associated with a lack of efficacy and acute infusion-related reactions and should instigate a change of therapy. When using the anti-CD20 monoclonal antibodies ocrelizumab and ofatumumab in the treatment of MS, it is not necessary to test for NAbs as these occur very infrequently. Alemtuzumab is immunogenic, but routine measurements of ADAs are not recommended as the antibodies in the pivotal 2-year trials at the population level did not influence lymphocyte depletion or repopulation, efficacy, or safety. However, in some individuals, NAbs led to poor lymphocyte depletion.

Immunogenicity of Oxford-AstraZeneca COVID-19 Vaccine in Vietnamese Health-Care Workers.

We studied the immunogenicity of the Oxford-AstraZeneca vaccine in health-care workers of a major infectious diseases hospital in Vietnam. We measured neutralizing antibodies before and 14 days after each dose, and at day 28 and month 3 after dose 1. A total of 554 workers (136 men and 418 women; age range, 22-71 years; median age, 36 years) participated with the study. Of the 144 participants selected for follow-up after dose 1, 104 and 94 gave blood for antibody measurement at weeks 6 and 8, and at month 3 after dose 1, respectively. The window time between the two doses was 6 weeks. At baseline, none had detectable neutralizing antibodies. After dose 1, the proportion of participants with detectable neutralizing antibodies increased from 27.3% (151 of 554) at day 14 to 78.0% (432 of 554) at day 28. Age correlated negatively with the development and the levels of neutralizing antibodies. However, at day 28, these differences were less profound, and women had a greater seroconversion rate and greater levels of neutralizing antibodies than men. After dose 2, these age and gender associations were not observable. In addition, the proportion of study participants with detectable neutralizing antibodies increased from 70.2% (73 of 104) before dose 2 (week 6, after dose 1) to 98.1% (102 of 104) 14 days later. At month 3, neutralizing antibodies decreased and 94.7% (89 of 94) of the study participants remained seropositive. The Oxford-AstraZeneca COVID-19 vaccine is immunogenic in Vietnamese health-care workers. These data are critical to informing the deployment of the COVID-19 vaccine in Vietnam and in Southeast Asia, where vaccination coverage remains inadequate.

Safety, Tolerability, and Pharmacokinetics of PF-06823859, an Anti-Interferon ß Monoclonal Antibody: A Randomized, Phase I, Single- and Multiple-Ascending-Dose Study.

This double-blind, randomized, placebo-controlled, dose-ascending, first-in-human study (NCT02766621) assessed the safety, tolerability, and pharmacokinetics (PK) of PF-06823859, an anti-interferon ß monoclonal antibody. Healthy subjects were randomized to single ascending doses (SADs) of intravenous PF-06823859 30, 100, 300, 900, or 2000 mg or placebo; to multiple ascending doses (MADs) of subcutaneous PF-06823859 100 or 300 mg or placebo (once every 2 weeks for a total of 3 doses); or to MAD of intravenous PF-06823859 600 mg or placebo (once every 3 weeks or once every 4 weeks for a total of 2 doses). The incidence, severity, and causal relationship of adverse events (AEs) were assessed, along with immunogenicity and PK. In total, 62 subjects were randomized to treatment (SAD, n = 35; MAD, n = 27). There were 76 treatment-emergent all-causality AEs in the SAD (PF-06823859: n = 25; placebo: n = 4) and MAD (PF-06823859: n = 40; placebo: n = 7) cohorts. In the SAD cohorts, all treatment-emergent all-causality AEs were mild in severity; 4 AEs of moderate severity were identified in the MAD cohorts. No dose-limiting AEs, serious AEs, treatment-related discontinuations, dose reductions, or deaths occurred. PF-06823859 exposure increased dose-proportionally, with half-life values ranging between 23 and 35 days. The estimated subcutaneous bioavailability was 43% to 44%. Immunogenicity incidence rates were low (antidrug antibodies, 12.5%; neutralizing antibodies, 2.1%). No immunogenically related clinical responses of concern were observed. In conclusion, PF-06823859 demonstrated an acceptable safety, tolerability, and PK profile that supports clinical development for treating disorders associated with increased interferon ß levels, such as dermatomyositis or systemic lupus erythematosus.

Fab and Fc contribute to maximal protection against SARS-CoV-2 following NVX-CoV2373 subunit vaccine with Matrix-M vaccination.

Recently approved vaccines have shown remarkable efficacy in limiting SARS-CoV-2-associated disease. However, with the variety of vaccines, immunization strategies, and waning antibody titers, defining the correlates of immunity across a spectrum of antibody titers is urgently required. Thus, we profiled the humoral immune response in a cohort of non-human primates immunized with a recombinant SARS-CoV-2 spike glycoprotein (NVX-CoV2373) at two doses, administered as a single- or two-dose regimen. Both antigen dose and boosting significantly altered neutralization titers and Fc-effector profiles, driving unique vaccine-induced antibody fingerprints. Combined differences in antibody effector functions and neutralization were associated with distinct levels of protection in the upper and lower respiratory tract. Moreover, NVX-CoV2373 elicited antibodies that functionally targeted emerging SARS-CoV-2 variants. Collectively, the data presented here suggest that a single dose may prevent disease via combined Fc/Fab functions but that two doses may be essential to block further transmission of SARS-CoV-2 and emerging variants.

Safety and immunogenicity of SARS-CoV-2 recombinant protein vaccine formulations in healthy adults: interim results of a randomised, placebo-controlled, phase 1-2, dose-ranging study.

BACKGROUND: CoV2 preS dTM is a stabilised pre-fusion spike protein vaccine produced in a baculovirus expression system being developed against SARS-CoV-2. We present interim safety and immunogenicity results of the first-in-human study of the CoV2 preS dTM vaccine with two different adjuvant formulations. METHODS: This phase 1-2, randomised, double-blind study is being done in healthy, SARS-CoV-2-seronegative adults in ten clinical research centres in the USA. Participants were stratified by age (18-49 years and ≥50 years) and randomly assigned using an interactive response technology system with block randomisation (blocks of varying size) to receive one dose (on day 1) or two doses (on days 1 and 22) of placebo or candidate vaccine, containing low-dose (effective dose 1·3 µg) or high-dose (2·6 µg) antigen with adjuvant AF03 (Sanofi Pasteur) or AS03 (GlaxoSmithKline) or unadjuvanted high-dose antigen (18-49 years only). Primary endpoints were safety, assessed up to day 43, and immunogenicity, measured as SARS-C0V-2 neutralising antibodies (geometric mean titres), assessed on days 1, 22, and 36 serum samples. Safety was assessed according to treatment received in the safety analysis set, which included all randomly assigned participants who received at least one dose. Neutralising antibody titres were assessed in the per-protocol analysis set for immunogenicity, which included participants who received at least one dose, met all inclusion and exclusion criteria, had no protocol deviation, had negative results in the neutralisation test at baseline, and had at least one valid post-dose serology sample. This planned interim analysis reports data up to 43 days after the first vaccination; participants in the trial will be followed up for 12 months after the last study injection. This trial is registered with ClinicalTrials.gov, NCT04537208, and is ongoing. FINDINGS: Between Sept 3 and Sept 29, 2020, 441 individuals (299 aged 18-49 years and 142 aged ≥50 years) were randomly assigned to one of the 11 treatment groups. The interim safety analyses included 439 (>99%) of 441 randomly assigned participants (299 aged 18-49 years and 140 aged ≥50 years). Neutralising antibody titres were analysed in 326 (74%) of 441 participants (235 [79%] of 299 aged 18-49 years and 91 [64%] of 142 aged ≥50 years). There were no vaccine-related unsolicited immediate adverse events, serious adverse events, medically attended adverse events classified as severe, or adverse events of special interest. Among all study participants, solicited local and systemic reactions of any grade after two vaccine doses were reported in 81% (95% CI 61-93; 21 of 26) of participants in the low-dose plus AF03 group, 93% (84-97; 74 of 80) in the low-dose plus AS03 group, 89% (70-98; 23 of 26) in the high-dose plus AF03 group, 95% (88-99; 81 of 85) in the high-dose plus AS03 group, 29% (10-56; five of 17) in the unadjuvanted high-dose group, and 21% (8-40; six of 29) in the placebo group. A single vaccine dose did not generate neutralising antibody titres above placebo levels in any group at days 22 or 36. Among participants aged 18-49 years, neutralising antibody titres after two vaccine doses were 13·1 (95% CI 6·40-26·9) in the low-dose plus AF03 group, 20·5 (13·1-32·1) in the low-dose plus AS03 group, 43·2 (20·6-90·4) in the high-dose plus AF03 group, 75·1 (50·5-112·0) in the high-dose plus AS03 group, 5·00 (not calculated) in the unadjuvanted high-dose group, and 5·00 (not calculated) in the placebo group. Among participants aged 50 years or older, neutralising antibody titres after two vaccine doses were 8·62 (1·90-39·0) in the low-dose plus AF03 group, 12·9 (7·09-23·4) in the low-dose plus AS03 group, 12·3 (4·35-35·0) in the high-dose plus AF03 group, 52·3 (25·3-108·0) in the high-dose plus AS03 group, and 5·00 (not calculated) in the placebo group. INTERPRETATION: The lower than expected immune responses, especially in the older age groups, and the high reactogenicity after dose two were probably due to higher than anticipated host-cell protein content and lower than planned antigen doses in the formulations tested, which was discovered during characterisation studies on the final bulk drug substance. Further development of the AS03-adjuvanted candidate vaccine will focus on identifying the optimal antigen formulation and dose. FUNDING: Sanofi Pasteur and Biomedical Advanced Research and Development Authority.

Design and application of nanoparticles as vaccine adjuvants against human corona virus infection.

In recent years, some viruses have caused a grave crisis to global public health, especially the human coronavirus. A truly effective vaccine is therefore urgently needed. Vaccines should generally have two features: delivering antigens and modulating immunity. Adjuvants have an unshakable position in the battle against the virus. In addition to the perennial use of aluminium adjuvant, nanoparticles have become the developing adjuvant candidates due to their unique properties. Here we introduce several typical nanoparticles and their antivirus vaccine adjuvant applications. Finally, for the combating of the coronavirus, we propose several design points, hoping to provide ideas for the development of personalized vaccines and adjuvants and accelerate the clinical application of adjuvants.

T cell-inducing vaccine durably prevents mucosal SHIV infection even with lower neutralizing antibody titers.

Recent efforts toward an HIV vaccine focus on inducing broadly neutralizing antibodies, but eliciting both neutralizing antibodies (nAbs) and cellular responses may be superior. Here, we immunized macaques with an HIV envelope trimer, either alone to induce nAbs, or together with a heterologous viral vector regimen to elicit nAbs and cellular immunity, including CD8+ tissue-resident memory T cells. After ten vaginal challenges with autologous virus, protection was observed in both vaccine groups at 53.3% and 66.7%, respectively. A nAb titer >300 was generally associated with protection but in the heterologous viral vector + nAb group, titers <300 were sufficient. In this group, protection was durable as the animals resisted six more challenges 5 months later. Antigen stimulation of T cells in ex vivo vaginal tissue cultures triggered antiviral responses in myeloid and CD4+ T cells. We propose that cellular immune responses reduce the threshold of nAbs required to confer superior and durable protection.

A live-attenuated Zika virus vaccine candidate induces sterilizing immunity in mouse models.

Zika virus (ZIKV) infection of pregnant women can cause a wide range of congenital abnormalities, including microcephaly, in the infant, a condition now collectively known as congenital ZIKV syndrome. A vaccine to prevent or significantly attenuate viremia in pregnant women who are residents of or travelers to epidemic or endemic regions is needed to avert congenital ZIKV syndrome, and might also help to suppress epidemic transmission. Here we report on a live-attenuated vaccine candidate that contains a 10-nucleotide deletion in the 3' untranslated region of the ZIKV genome (10-del ZIKV). The 10-del ZIKV is highly attenuated, immunogenic, and protective in type 1 interferon receptor-deficient A129 mice. Crucially, a single dose of 10-del ZIKV induced sterilizing immunity with a saturated neutralizing antibody titer, which no longer increased after challenge with an epidemic ZIKV, and completely prevented viremia. The immunized mice also developed a robust T cell response. Intracranial inoculation of 1-d-old immunocompetent CD-1 mice with 1 × 104 infectious focus units (IFU) of 10-del ZIKV caused no mortality, whereas infections with 10 IFU of wild-type ZIKV were lethal. Mechanistically, the attenuated virulence of 10-del ZIKV may be due to decreased viral RNA synthesis and increased sensitivity to type-1-interferon inhibition. The attenuated 10-del ZIKV was incapable of infecting mosquitoes after oral feeding of spiked-blood meals, representing an additional safety feature. Collectively, the safety and efficacy results suggest that further development of this promising, live-attenuated ZIKV vaccine candidate is warranted.

Geldanamycin Reduces Acute Respiratory Distress Syndrome and Promotes the Survival of Mice Infected with the Highly Virulent H5N1 Influenza Virus.

Infections with lethal influenza viruses lead to acute lung injury (ALI) or acute respiratory distress syndrome (ARDS), which may be related to the activation of the host's immune system. Here, in our study, male C57BL/6 mice were infected with 10 LD50 of the H5N1 influenza virus and treated with geldanamycin or oseltamivir 2 h after infection. Lung injury was assessed by histopathology on days 4 and 7. The viral load was quantified by measuring the NP gene expression level on days 2, 4, and 7. Levels of cytokines and chemokines in bronchoalveolar lavage fluids and inflammatory cells were analyzed at different time points. Geldanamycin administration prolonged survival in mice and dramatically reduced lung injury and pulmonary inflammatory compared with other mice. Viral loads in geldanamycin-treated mice also significantly reduced compared with non-treated mice, but not to the extent as the oseltamivir-treated mice. Furthermore, the geldanamycin treatment markedly reduced the production of major proinflammatory cytokines and chemokines and attenuated the infiltration and activation of immune cells, but it did not alter the generation of virus-neutralizing antibodies. In conclusion, geldanamycin plays an important role in attenuating virus infection-induced ALI/ARDS by reducing the host's inflammatory responses and may provide an important reference for clinical treatments.

Non-toxic perfringolysin O and α-toxin derivatives as potential vaccine candidates against bovine necrohaemorrhagic enteritis.

Bovine necrohaemorrhagic enteritis is a fatal Clostridium perfringens type A-induced disease that is characterised by sudden death. Recently the involvement of perfringolysin O and α-toxin in the development of necrohaemorrhagic lesions in the gut of calves was suggested, and thus derivatives of these toxins are potentially suitable as vaccine antigens. In the current study, the perfringolysin O derivative PFOL491D, alone or in combination with α-toxin derivative GST-cpa247-370, was evaluated as possible vaccine candidate, using in vitro assays. PFOL491D showed no haemolytic effect on horse red blood cells and no cytotoxic effect on bovine endothelial cells. Furthermore, calves immunised with PFOL491D raised antibodies against perfringolysin O that could inhibit the perfringolysin O-associated haemolytic activity on horse red blood cells. Antisera from calves immunised with PFOL491D had a significantly higher neutralising capacity against the cytotoxic effect of C. perfringens culture supernatant to bovine endothelial cells than serum from control calves (P <0.05). Immunisation of calves with PFOL491D in combination with GST-cpa247-370 elicited antibodies against perfringolysin O and α-toxin and consequently inhibited both the perfringolysin O-associated haemolytic activity and the α-toxin-associated lecithinase activity in vitro. Additionally, the neutralising ability of these antisera on the cytotoxic effect of C. perfringens culture supernatant to bovine endothelial cells was significantly higher than that from calves immunised with PFOL491D (P <0.001). In conclusion, perfringolysin O derivative PFOL491D is an immunogenic antigen that can potentially be used to produce vaccine against bovine necrohaemorrhagic enteritis. Including α-toxin derivative GST-cpa247-370 has an additional protective effect and therefore vaccination of calves with a combination of both antigens seems even more promising.