Safety and Immunogenicity of Inactivated Whole Virion COVID-19 Vaccine CoviVac in Clinical Trials in 18-60 and 60+ Age Cohorts

We present the results of a randomized, double-blind, placebo-controlled, multi-center clinical trial phase I/II of the tolerability, safety, and immunogenicity of the inactivated whole virion concentrated purified coronavirus vaccine CoviVac in volunteers aged 18-60 and open multi-center comparative phase IIb clinical trial in volunteers aged 60 years and older. The safety of the vaccine was assessed in 400 volunteers in the 18-60 age cohort who received two doses of the vaccine (n = 300) or placebo (n = 100) and in 200 volunteers in 60+ age cohort all of whom received three doses of the vaccine. The studied vaccine has shown good tolerability and safety. No deaths, serious adverse events (AEs), or other significant AEs related to vaccination have been detected. The most common AE in vaccinated participants was pain at the injection site (p < 0.05). Immunogenicity assessment in stage 3 of Phase II was performed on 167 volunteers (122 vaccinated and 45 in Placebo Group) separately for the participants who were anti-SARS-CoV-2 nAB negative (69/122 in Vaccine Group and 28/45 in Placebo Group) or positive (53/122 in Vaccine Group and 17/45 in Placebo Group) at screening. On Day 42 after the 1st vaccination, the seroconversion rate in participants who were seronegative at screening was 86.9%, with the average geometric mean neutralizing antibody (nAB) titer of 1:20. A statistically significant (p < 0.05) increase in IFN-γ production by peptide-stimulated T-cells was observed at Days 14 and 21 after the 1st vaccination. In participants who were seropositive at screening but had nAB titers below 1:256, the rate of fourfold increase in nAB levels was 85.2%, while in the participants with nAB titers > 1:256, the rate of fourfold increase in nAB levels was below 45%; the participants who were seropositive at screening of the 2nd vaccination did not lead to a significant increase in nAB titers. In conclusion, inactivated vaccine CoviVac has shown good tolerability and safety, with over 85% NT seroconversion rates after complete vaccination course in participants who were seronegative at screening in both age groups: 18-60 and 60+. In participants who were seropositive at screening and had nAB titers below 1:256, a single vaccination led to a fourfold increase in nAB levels in 85.2% of cases. These findings indicate that CoviVac can be successfully used both for primary vaccination in a two-dose regimen and for booster vaccination as a single dose in individuals with reduced neutralizing antibody levels.

Geographic and Temporal Variability of Hepatitis E Virus Circulation in the Russian Federation

The factors influencing hepatitis E virus (HEV) circulation remain largely unexplored. We investigated HEV seroprevalence in humans and the prevalence of infection in farm pigs and rabbits in different regions of the Russian Federation, as well as the genetic diversity and population dynamics of the HEV. The anti-HEV IgG antibody detection rates in the general population increase significantly with age, from 1.5% in children and adolescents under 20 years old to 4.8% in adults aged between 20 and 59 years old to 16.7% in people aged 60 years and older. HEV seroprevalence varies between regions, with the highest rate observed in Belgorod Region (16.4% compared with the national average of 4.6%), which also has the country's highest pig population. When compared with the archival data, both increases and declines in HEV seroprevalence have been observed within the last 10 years, depending on the study region. Virus shedding has been detected in 19 out of the 21 pig farms surveyed. On one farm, the circulation of the same viral strain for five years was documented. All the human and animal strains belonged to the HEV-3 genotype, with its clade 2 sequences being predominant in pigs. The sequences are from patients, pigs, and sewage from pig farms clustered together, suggesting a zoonotic infection in humans and possible environmental contamination. The HEV-3 population size that was predicted using SkyGrid reconstruction demonstrated exponential growth in the 1970s-1990s, with a subsequent decline followed by a short rise around the year 2010, the pattern being similar to the dynamics of the pig population in the country. The HEV-3 reproduction number (Re) that was predicted using birth-death skyline analysis has fluctuated around 1 over the past 20 years in Russia but is 10 times higher in Belgorod Region. In conclusion, the HEV-3 circulation varies both geographically and temporally, even within a single country. The possible factors contributing to this variability are largely related to the circulation of the virus among farm pigs.

Vaccination With Oral Polio Vaccine Reduces COVID-19 Incidence

Background

Effective response to emerging pandemic threats is complicated by the need to develop specific vaccines and other medical products. The availability of broadly specific countermeasures that could be deployed early in the pandemic could significantly alter its course and save countless lives. Live attenuated vaccines (LAVs) were shown to induce non-specific protection against a broad spectrum of off-target pathogens by stimulating innate immune responses. The purpose of this study was to evaluate the effect of immunization with bivalent Oral Poliovirus Vaccine (bOPV) on the incidence of COVID-19 and other acute respiratory infections (ARIs).

Methods and Findings

A randomized parallel-group comparative study was conducted in Kirov Medical University. 1115 healthy volunteers aged 18 to 65 were randomized into two equal groups, one of which was immunized orally with a single dose of bOPV “BiVac Polio” and another with placebo. The study participants were monitored for three months for respiratory illnesses including COVID-19. The endpoint was the incidence of acute respiratory infections and laboratory confirmed COVID-19 in both groups during 3 months after immunization. The number of laboratory-confirmed cases of COVID-19 was significantly lower in the vaccinated group than in placebo (25 cases vs. 44, p=0.036). The difference between the overall number of clinically diagnosed respiratory illnesses in the two groups was not statistically significant.

Conclusions

Immunization with bOPV reduced the number of laboratory-confirmed COVID-19 cases, consistent with the original hypothesis that LAVs induce non-specific protection against off-target infections. The findings are in line with previous observations of the protective effects of OPV against seasonal influenza and other viral and bacterial pathogens. The absence of a statistically significant effect on the total number of ARIs may be due to the insufficient number of participants and heterogeneous etiology of ARIs. OPV could be used to complement specific coronavirus vaccines, especially in regions of the world where the vaccines are unavailable, and as a stopgap measure for urgent response to future emerging infections. Clinical trial registration number NCT05083039 at clinicaltrals.gov https://clinicaltrials.gov/ct2/show/NCT05083039?term=NCT05083039&draw=2&rank=1

Long-term humoral immunogenicity, safety and protective efficacy of inactivated vaccine against COVID-19 (CoviVac) in preclinical studies

The unprecedented in recent history global COVID-19 pandemic urged the implementation of all existing vaccine platforms to ensure the availability of the vaccines against COVID-19 to every country in the world. Despite the multitude of high-quality papers describing clinical trials of different vaccine products, basic detailed data on general toxicity, reproductive toxicity, immunogenicity, protective efficacy and durability of immune response in animal models are scarce. Here, we developed a β-propiolactone-inactivated whole virion vaccine CoviVac and assessed its safety, protective efficacy, immunogenicity and stability of the immune response in rodents and non-human primates. The vaccine showed no signs of acute/chronic, reproductive, embryo- and fetotoxicity, or teratogenic effects, as well as no allergenic properties in studied animal species. The vaccine induced stable and robust humoral immune response both in form of specific anti-SARS-CoV-2 IgG and NAbs in mice, Syrian hamsters, and common marmosets. The NAb levels did not decrease significantly over the course of one year. The course of two immunizations protected Syrian hamsters from severe pneumonia upon intranasal challenge with the live virus. Robustness of the vaccine manufacturing process was demonstrated as well. These data encouraged further evaluation of CoviVac in clinical trials.

Therapeutic Vaccines Against Human Papilloma Viruses: Achievements and Prospects

Human papillomaviruses of high carcinogenic risk (HR HPVs) are major etiological agents of malignant diseases of the cervix, vulva, penis, anal canal, larynx, head, and neck. Prophylactic vaccination against HPV, which mainly covers girls and women under 25, does not prevent vertical and horizontal HPV transmission in infants and children and does not have a therapeutic effect. As a result, a significant proportion of the population is not protected from the HPV infection and development of HPV-associated neoplastic transformation and cancer, which indicates the need for development and introduction of therapeutic HPV vaccines. Unlike prophylactic vaccines aimed at the formation of virus-neutralizing antibodies, therapeutic vaccines elicit cellular immune response leading to the elimination of infected and malignant cells expressing viral proteins. The ideal targets for vaccine immunotherapy are highly conserved HR HPV oncoproteins E6 and E7 expressed in precancerous and tumor tissues. Here, we describe expression of these proteins during different stages of HPV infection, their antigenic and immunogenic properties, and T-cell epitopes, the response to which correlates with natural regression of HPV-induced neoplastic changes. The review describes patterns of E6 and E7 oncoproteins presentation to the immune system as components of candidate vaccines along with the results of the most promising preclinical trials and animal models used in these trials. Special attention is paid to vaccine candidates which have shown efficacy in clinical trials in patients with HPV-associated neoplastic changes.

Immunization with live nonpathogenic H5N3 duck influenza virus protects chickens against highly pathogenic H5N1 virus

Development of an effective, broadly-active and safe vaccine for protection of poultry from H5N1 highly pathogenic avian influenza viruses (HPAIVs) remains an important practical goal. In this study we used a low pathogenic wild aquatic bird virus isolate А/duck/Moscow/4182/2010 (H5N3) (dk/4182) as a live candidate vaccine. We compared this virus with four live 1:7 reassortant anti-H5N1 candidate vaccine viruses with modified hemagglutinin from either A/Vietnam/1203/04 (H5N1) or A/Kurgan/3/05 (H5N1) and the rest of the genes from either H2N2 cold-adapted master strain A/Leningrad/134/17/57 (rVN-Len and rKu-Len) or H6N2 virus A/gull/Moscow/3100/2006 (rVN-gull and rKu-gull). The viruses were tested in parallel for pathogenicity, immunogenicity and protective effectiveness in chickens using aerosol, intranasal and oral routes of immunization. All five viruses showed zero pathogenicity indexes in chickens. Viruses rVN-gull and rKu-gull were immunogenic and protective, but they were insufficiently attenuated and caused significant mortality of 1-day-old chickens. The viruses with cold-adapted backbones (rVN-Len and rKu-Len) were completely nonpathogenic, but they were significantly less immunogenic and provided lower protection against lethal challenge with HPAIV A/Chicken/Kurgan/3/05 (H5N1) as compared with three other vaccine candidates. Unlike other four viruses, dk/4182 was both safe and highly immunogenic in chickens of any age regardless of inoculation route. Single administration of 106 TCID50 of dk/4182 virus via drinking water provided complete protection of 30-days-old chickens from 100 LD50 of the challenge virus. Our results suggest that low pathogenic viruses of wild aquatic birds can be used as safe and effective live poultry vaccines against highly pathogenic avian viruses.

Impact of Universal Hepatitis B Vaccination on Prevalence, Infection-Associated Morbidity and Mortality, and Circulation of Immune Escape Variants in Russia

Vaccination of newborns against hepatitis B (HB) was introduced in Russia in 1998. Since then the incidence of acute HB has rapidly declined. However, prevalence of chronic HB remains stable. The aim of this study was to estimate the effect of vaccination on HBV-associated morbidity, and to assess the prevalence of HBV immune escape variants after 10 years of vaccination.

[GENUS ANELLOVIRIDAE VIRUSES IN CHRONIC LIVER DISEASE]

AIM

Viruses from genus Anelloviridae (TTV, TTMDV and TTMV) are small DNA viruses that are widespread in human popu- lation. Data on tissue tropism, cell localization and morphometry of anelloviruses are scarce. The purpose of this study was to determine the prevalence of TTV, TTMDV and TTMV in persons with liver disease and in healthy individuals, as well as electron-microscopic verification of Anelloviridae species.

METHODS

Detection of anelloviral DNA was performed in serum samples from 203 patients with liver diseases of various etiology and 115 voluntary blood donors using PCR with primers allowing to differentiate TTV, TTMDV TTMV based on the length of amplified fragment. Histopathological and electron microscopic studies were performed for liver biopsy specimens from 203 patients with liver disease.

RESULTS

High prevalence (70-90%) of all three anelloviruses in healthy individuals and patients with liver disease was demonstrated, with high frequency of triple TTV, TTMDV and TTMV infection (52.2-55.7%). Electron-microscopic study of liver biopsy specimens from TTMDV monoinfected patients gave a submicroscopic image of TTMDV virions with diameter 35.86 ± 2.04 nm. Electron microscopic studies confirmed the nature of liver damage in TTMDV monoinfection: accumulation of virus in the hepatocytes, significant cyropathy with enlightenment matrix of the cytoplasm and reduction of intracellula organelles involved in protein synthesis, portal and perivascular perisinusoidal fibrosis. TTV, TTMDV and TTMV virions were dentified in hepatocytes, confirming these viruses to be hepatotropic.

CONCLUSION

Our results demonstrate that anelloviruses are lymphotropic viruses, individual genotypes of those might be hepatotropic and pathogenic to liver.