Safety and immunogenicity of a heterologous booster with an RBD virus-like particle vaccine following two- or three-dose inactivated COVID-19 vaccine

LYB001 is an innovative recombinant SARS-CoV-2 vaccine that displays a repetitive array of the spike glycoprotein's receptor-binding domain (RBD) on a virus-like particle (VLP) vector to boost the immune system, produced using Covalink plug-and-display protein binding technology. LYB001's safety and immunogenicity were assessed in 119 participants receiving a booster with (1) 30 μg LYB001 (I-I-30 L) or CoronaVac (I-I-C), (2) 60 μg LYB001 (I-I-60 L) or CoronaVac in a ratio of 2:1 after two-dose primary series of inactivated COVID-19 vaccine, and (3) 30 μg LYB001 (I-I-I-30 L) after three-dose inactivated COVID-19 vaccine. A well-tolerated reactogenicity profile was observed for LYB001 as a heterologous booster, with adverse reactions being predominantly mild in severity and transient. LYB001 elicited a substantial increase in terms of the neutralizing antibody response against prototype SARS-CoV-2 28 days after booster, with GMT (95%CI) of 1237.8 (747.2, 2050.6), 554.3 (374.6, 820.2), 181.9 (107.6, 307.6), and 1200.2 (831.5, 1732.3) in the I-I-30 L, I-I-60 L, I-I-C, and I-I-I-30 L groups, respectively. LYB001 also elicited a cross-neutralizing antibody response against the BA.4/5 strain, dominant during the study period, with GMT of 201.1 (102.7, 393.7), 63.0 (35.1, 113.1), 29.2 (16.9, 50.3), and 115.3 (63.9, 208.1) in the I-I-30 L, I-I-60 L, I-I-C, and I-I-I-30 L groups, respectively, at 28 days after booster. Additionally, RBD-specific IFN-γ, IL-2, IL-4 secreting T cells dramatically increased at 14 days after a single LYB001 booster. Our data confirmed the favorable safety and immunogenicity profile of LYB001 and supported the continued clinical development of this promising candidate that utilizes the VLP platform to provide protection against COVID-19.

Immunogenicity and safety of an Escherichia coli-produced human papillomavirus (types 6/11/16/18/31/33/45/52/58) L1 virus-like-particle vaccine: a phase 2 double-blind, randomized, controlled trial

The Escherichia coli-produced human papillomavirus (HPV) 16/18 bivalent vaccine (Cecolin) has received prequalification by the World Health Organization based on its high efficacy and good safety profile. We aimed to evaluate the immunogenicity and safety of the second-generation nonavalent HPV 6/11/16/18/31/33/45/52/58 vaccine (Cecolin 9) through the randomized, blinded phase 2 clinical trial. Eligible healthy women aged 18-45 years were randomly (1:1) allocated to receive three doses of 1.0 mL (270 µg) of Cecolin 9 or placebo with a 0-1-6-month schedule. The primary endpoint was the seroconversion rate and geometric mean titer of neutralizing antibodies (nAbs) one month after the full vaccination course (month 7). The secondary endpoint was the safety profile including solicited adverse reactions occurring within 7 d, adverse events (AEs) occurring within 30 d after each dose, and serious adverse events (SAEs) occurring during the 7-month follow-up period. In total, 627 volunteers were enrolled and randomly assigned to Cecolin 9 (n = 313) or placebo (n = 314) group in Jiangsu Province, China. Almost all participants in the per-protocol set for immunogenicity (PPS-I) seroconverted for nAbs against all the nine HPV types at month 7, while two failed to seroconvert for HPV 11 and one did not seroconvert for HPV 52. The incidence rates of total AEs in the Cecolin 9 and placebo groups were 80.8% and 72.9%, respectively, with the majority of them being mild and recovering shortly. None of the SAEs were considered related to vaccination. In conclusion, the E. coli-produced 9-valent HPV (9vHPV) vaccine candidate was well tolerated and immunogenic, which warrants further efficacy studies in larger populations.

Safety, immunogenicity, and protection provided by unadjuvanted and adjuvanted formulations of a recombinant plant-derived virus-like particle vaccine candidate for COVID-19 in nonhuman primates

Although antivirals are important tools to control severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, effective vaccines are essential to control the current coronavirus disease 2019 (COVID-19) pandemic. Plant-derived virus-like particle (VLP) vaccine candidates have previously demonstrated immunogenicity and efficacy against influenza. Here, we report the immunogenicity and protection induced in rhesus macaques by intramuscular injections of a VLP bearing a SARS-CoV-2 spike protein (CoVLP) vaccine candidate formulated with or without Adjuvant System 03 (AS03) or cytidine-phospho-guanosine (CpG) 1018. Although a single dose of the unadjuvanted CoVLP vaccine candidate stimulated humoral and cell-mediated immune responses, booster immunization (at 28 days after priming) and adjuvant administration significantly improved both responses, with higher immunogenicity and protection provided by the AS03-adjuvanted CoVLP. Fifteen micrograms of CoVLP adjuvanted with AS03 induced a polyfunctional interleukin-2 (IL-2)-driven response and IL-4 expression in CD4 T cells. Animals were challenged by multiple routes (i.e., intratracheal, intranasal, and ocular) with a total viral dose of 106 plaque-forming units of SARS-CoV-2. Lower viral replication in nasal swabs and bronchoalveolar lavage fluid (BALF) as well as fewer SARS-CoV-2-infected cells and immune cell infiltrates in the lungs concomitant with reduced levels of proinflammatory cytokines and chemotactic factors in the BALF were observed in animals immunized with the CoVLP adjuvanted with AS03. No clinical, pathologic, or virologic evidence of vaccine-associated enhanced disease was observed in vaccinated animals. The CoVLP adjuvanted with AS03 was therefore selected for vaccine development and clinical trials.

Effect of a Chikungunya Virus-Like Particle Vaccine on Safety and Tolerability Outcomes: A Randomized Clinical Trial

IMPORTANCE

Chikungunya virus (CHIKV) is a mosquito-borne Alphavirus prevalent worldwide. There are currently no licensed vaccines or therapies.

OBJECTIVE

To evaluate the safety and tolerability of an investigational CHIKV virus-like particle (VLP) vaccine in endemic regions.

DESIGN, SETTING, AND PARTICIPANTS

This was a randomized, placebo-controlled, double-blind, phase 2 clinical trial to assess the vaccine VRC-CHKVLP059-00-VP (CHIKV VLP). The trial was conducted at 6 outpatient clinical research sites located in Haiti, Dominican Republic, Martinique, Guadeloupe, and Puerto Rico. A total of 400 healthy adults aged 18 through 60 years were enrolled after meeting eligibility criteria. The first study enrollment occurred on November 18, 2015; the final study visit, March 6, 2018.

INTERVENTIONS

Participants were randomized 1:1 to receive 2 intramuscular injections 28 days apart (20 µg, n = 201) or placebo (n = 199) and were followed up for 72 weeks.

MAIN OUTCOMES AND MEASURES

The primary outcome was the safety (laboratory parameters, adverse events, and CHIKV infection) and tolerability (local and systemic reactogenicity) of the vaccine, and the secondary outcome was immune response by neutralization assay 4 weeks after second vaccination.

RESULTS

Of the 400 randomized participants (mean age, 35 years; 199 [50%] women), 393 (98%) completed the primary safety analysis. All injections were well tolerated. Of the 16 serious adverse events unrelated to the study drugs, 4 (25%) occurred among 4 patients in the vaccine group and 12 (75%) occurred among 11 patients in the placebo group. Of the 16 mild to moderate unsolicited adverse events that were potentially related to the drug, 12 (75%) occurred among 8 patients in the vaccine group and 4 (25%) occurred among 3 patients in the placebo group. All potentially related adverse events resolved without clinical sequelae. At baseline, there was no significant difference between the effective concentration (EC50)-which is the dilution of sera that inhibits 50% infection in viral neutralization assay-geometric mean titers (GMTs) of neutralizing antibodies of the vaccine group (46; 95% CI, 34-63) and the placebo group (43; 95% CI, 32-57). Eight weeks following the first administration, the EC50 GMT in the vaccine group was 2005 (95% CI, 1680-2392) vs 43 (95% CI, 32-58; P < .001) in the placebo group. Durability of the immune response was demonstrated through 72 weeks after vaccination.

CONCLUSIONS AND RELEVANCE

Among healthy adults in a chikungunya endemic population, a virus-like particle vaccine compared with placebo demonstrated safety and tolerability. Phase 3 trials are needed to assess clinical efficacy.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02562482.

Vaccination with a chikungunya virus-like particle vaccine exacerbates disease in aged mice

INTRODUCTION

Chikungunya virus (CHIKV) is a re-emerging pathogen responsible for causing outbreaks of febrile disease accompanied with debilitating joint pain. Symptoms typically persist for two weeks, but more severe and chronic chikungunya illnesses have been reported, especially in the elderly. Currently, there are no licensed vaccines or antivirals against CHIKV available. In this study, we combined a CHIK virus-like particle (VLP) vaccine with different adjuvants to enhance immunogenicity and protection in both, adult and aged mice.

METHODS

CHIK VLP-based vaccines were tested in 6-8-week-old (adult) and 18-24-month-old (aged) female C57BL/6J mice. Formulations contained CHIK VLP alone or adjuvants: QuilA, R848, or Imject Alum. Mice were vaccinated three times via intramuscular injections. CHIKV-specific antibody responses were characterized by IgG subclass using ELISA, and by microneutralization assays. In addition, CHIKV infections were characterized in vaccinated and non-vaccinated adult mice and compared to aged mice.

RESULTS

In adult mice, CHIKV infection of the right hind foot induced significant swelling, which peaked by day 7 post-infection at approximately 170% of initial size. Viral titers peaked at 2.53 × 1010 CCID50/ml on day 2 post-infection. Mice vaccinated with CHIK VLP-based vaccines developed robust anti-CHIKV-specific IgG antibody responses that were capable of neutralizing CHIKV in vitro. CHIK VLP alone or CHIK plus QuilA administered by IM injections protected 100% of mice against CHIKV. In contrast, the antibody responses elicited by the VLP-based vaccines were attenuated in aged mice, with negligible neutralizing antibody titers detected. Unvaccinated, aged mice were resistant to CHIKV infection, while vaccination with CHIKV VLPs exacerbated disease.

CONCLUSIONS

Unadjuvanted CHIK VLP vaccination elicits immune responses that protect 100% of adult mice against CHIKV infection. However, an improved vaccine/adjuvant combination is still necessary to enhance the protective immunity against CHIKV in the aged.

A Phase 2 randomized, observer-blind, placebo-controlled, dose-ranging trial of aluminum-adjuvanted respiratory syncytial virus F particle vaccine formulations in healthy women of childbearing age

OBJECTIVE

Respiratory syncytial virus (RSV) causes significant morbidity and mortality in infants. We are developing an RSV fusion (F) protein nanoparticle vaccine for immunization of third trimester pregnant women to passively protect infants through transfer of RSV-specific maternal antibodies. The present trial was performed to assess the immunogenicity and safety of several formulations of RSV F vaccine in 1-dose or 2-dose schedules.

METHODS

Placebo, or vaccine with 60μg or 120μg RSV F protein and 0.2, 0.4, or 0.8mg aluminum, were administered intramuscularly on Days 0 and 28 to healthy women 18-35years old. Immunogenicity was assessed from Days 0 through 91 based on anti-F IgG and palivizumab-competitive antibody (PCA) by ELISA, and RSV A and B neutralizing antibodies by microneutralization (MN) assay. Solicited adverse events were collected through Day 7 and unsolicited adverse events through Day 91.

RESULTS

All formulations were well-tolerated, with no treatment-related serious adverse events. Anti-F IgG and PCA responses were correlated and increased after both doses, while MN increased significantly only after the first dose, then plateaued. The timeliest and most robust antibody responses followed one dose of 120μg RSV F protein and 0.4mg aluminum, but persistence through 91days was modestly (∼25%) superior following two doses of 60μg RSV F protein and 0.8mg aluminum. Western blot analysis showed RSV infections in active vaccinees were reduced by 52% overall (p=0.009 overall) over the Day 0 through 90 period.

CONCLUSIONS

RSV F nanoparticle vaccine formulations were well tolerated and immunogenic. The optimal combination of convenience and rapid response for immunization in the third trimester occurred with 120μg RSV F and 0.4mg aluminum, which achieved peak immune responses in 14days and sufficient persistence through 91days to allow for passive transfer of IgG antibodies to the fetus. NCT01960686.

Combined virus-like particle and fusion protein-encoding DNA vaccination of cotton rats induces protection against respiratory syncytial virus without causing vaccine-enhanced disease

A safe and effective vaccine against respiratory syncytial virus (RSV) should confer protection without causing vaccine-enhanced disease. Here, using a cotton rat model, we investigated the protective efficacy and safety of an RSV combination vaccine composed of F-encoding plasmid DNA and virus-like particles containing RSV fusion (F) and attachment (G) glycoproteins (FFG-VLP). Cotton rats with FFG-VLP vaccination controlled lung viral replication below the detection limit, and effectively induced neutralizing activity and antibody-secreting cell responses. In comparison with formalin inactivated RSV (FI-RSV) causing severe RSV disease after challenge, FFG-VLP vaccination did not cause weight loss, airway hyper-responsiveness, IL-4 cytokines, histopathology, and infiltrates of proinflammatory cells such as eosinophils. FFG-VLP was even more effective in preventing RSV-induced pulmonary inflammation than live RSV infections. This study provides evidence that FFG-VLP can be developed into a safe and effective RSV vaccine candidate.

A novel intramuscular bivalent norovirus virus-like particle vaccine candidate--reactogenicity, safety, and immunogenicity in a phase 1 trial in healthy adults

BACKGROUND

Noroviruses are the most important viral causes of gastroenteritis-related morbidity and mortality. A randomized, double-blind, placebo-controlled study evaluated an adjuvanted bivalent intramuscular norovirus virus-like particle (VLP) vaccine.

METHODS

Forty-eight adults aged 18-49 years received either 2 doses containing genotype GI.1 VLP and a consensus GII.4 VLP or 2 doses of placebo. Doses (5 µg, 15 µg, 50 µg, or 150 µg of each VLP) were administered 4 weeks apart in the first stage. Subsequently, 54 adults, aged 18-49 (n=16), 50-64 (n=19), and 65-85 (n=19) years, received 2 doses of vaccine containing 50 µg of each VLP. Total and class-specific antibody responses, as well as histoblood group antigen (HBGA) blocking antibody responses, were measured before and after each dose.

RESULTS

Local reactions were mainly injection site pain/tenderness, with no reported fever or vaccine-related serious adverse events. One dose of vaccine containing 50 µg of each VLP increased GI.1 geometric mean titers (GMTs) by 118-fold, 83-fold, and 24-fold and increased GII.4 GMTs by 49-fold, 25-fold, and 9-fold in subjects aged 18-49, 50-64, and 65-83 years, respectively. Serum antibody responses peaked at day 7 after the first dose, with no evidence of boosting following a second dose. Most subjects achieved HBGA-blocking antibody titers of ≥200.

CONCLUSIONS

The vaccine was well tolerated and immunogenic. Rapid immune response to a single dose may be particularly useful in military personnel and travelers and in the control of outbreaks. Clinical Trials Registration. NCT01168401.

Morphologically virus-like fullerenol nanoparticles act as the dual-functional nanoadjuvant for HIV-1 vaccine

Fullerenol, which self-assembles into virus-sized nanoparticles, is designed as a dual-functional nanoadjuvant to generate comparable immune responses to the HIV DNA vaccine. It shows promising adjuvant activity via various immunization routes, decreasing the antigen dosage and immunization frequency while maintaining immunity levels and inducing TEM -biased immunity to combat the infection at early stage. The underlying mechanisms by which fullerenol-based formulation induces above-mentioned polyvalent immune responses are involved in activating multiple TLRs signaling pathways.

A review of clinical trials of human papillomavirus prophylactic vaccines

End of study analyses of the phase III trials of prophylactic human papillomavirus (HPV) virus-like particle (VLP) vaccines in young women are now largely completed. Two distinct vaccines were evaluated, Gardasil(®) (Merck & Co., Whitehouse Station, NJ USA) a quadrivalent vaccine containing VLPs of types 6, 11, 16 and 18 and Cervarix(®) (GlaxoSmithKline Biologicals, Rixensart, Belgium), a bivalent vaccine containing VLPs of types 16 and 18. Both vaccines exhibited excellent safety and immunogenicity profiles. The vaccines also demonstrated remarkably high and similar efficacy against the vaccine-targeted types for a range of cervical endpoints from persistent infection to cervical intraepithelial neoplasia grade 3 (CIN3) in women naïve to the corresponding type at the time of vaccination. However, protection from incident infection or disease from non-vaccine types was restricted, and the vaccines had no effect on prevalent infection or disease. Gardasil(®) also demonstrated strong protection against genital warts and vulvar/vaginal neoplasia associated with the vaccine types. In other trials, Gardasil(®) protected mid-adult women from incident infection and CIN caused by the vaccine types and protected men for incident infection, genital warts and anal intraepithelial neoplasia by the vaccine types. Cervarix(®) protected against vaccine-targeted anal infections in women in an end of study evaluation. For practical reasons, efficacy studies have not been conducted in the primary target populations of current vaccination programs, adolescent girls and boys. However, immunogenicity bridging studies demonstrating excellent safety and strong immune responses in adolescence, coupled with the documentation of durable antibody responses and protection in young adults, leads to an optimistic projection of the effectiveness of the vaccines in adolescent vaccination programs. Taken together, the excellent clinical trial results strongly support the potential of the vaccines as high value public health interventions and justify their widespread implementation to prevent anogenital HPV infections and their associated neoplasia. This article forms part of a special supplement entitled "Comprehensive Control of HPV Infections and Related Diseases" Vaccine Volume 30, Supplement 5, 2012.

Virus-like particle (VLP)-based vaccines for pandemic influenza: performance of a VLP vaccine during the 2009 influenza pandemic

The influenza pandemic of 2009 demonstrated the inability of the established global capacity for egg-based vaccine production technology to provide sufficient vaccine for the population in a timely fashion. Several alternative technologies for developing influenza vaccines have been proposed, among which non-replicating virus-like particles (VLPs) represent an attractive option because of their safety and immunogenic characteristics. VLP vaccines against pandemic influenza have been developed in tobacco plant cells and in Sf9 insect cells infected with baculovirus that expresses protein genes from pandemic influenza strains. These technologies allow rapid and large-scale production of vaccines (3-12 weeks). The 2009 influenza outbreak provided an opportunity for clinical testing of a pandemic influenza VLP vaccine in the midst of the outbreak at its epicenter in Mexico. An influenza A(H1N1)2009 VLP pandemic vaccine (produced in insect cells) was tested in a phase II clinical trial involving 4,563 healthy adults. Results showed that the vaccine is safe and immunogenic despite high preexisting anti-A(H1N1)2009 antibody titers present in the population. The safety and immunogenicity profile presented by this pandemic VLP vaccine during the outbreak in Mexico suggests that VLP technology is a suitable alternative to current influenza vaccine technologies for producing pandemic and seasonal vaccines.