Immunogenicity and Safety of an F-Genotype Attenuated Mumps Vaccine in Healthy 8- to 24-Month-Old Children

Standard definition of a clinical case of mumps and diagnostic effectiveness of the test systems used in the modern period

Introduction. Registration of regular epidemic outbreaks of mumps infection among young people, difficulties in the clinical diagnosis of the disease, the presence of specific clinical manifestations in adults with a severe course of infection make it necessary the improvement of the quality of diagnosis of the disease. The aim of the work is to develop a standard definition of a clinical case of mumps and to conduct a comparative assessment of the effectiveness of the diagnostic test systems used for mumps diagnostics based on the determination of their sensitivity and specificity. Materials and methods. To develop a standard definition of a clinical case of mumps based on ten combined clinical and laboratory parameters, a mathematical model was built using the logistic regression method. The study included 84 patients with mumps infection (main group) and 66 patients with non-epidemic sialoadenitis (comparison group). For a comparative evaluation of the diagnostic systems VectoParotitis-IgM, VectoParotitis-IgG, ELISA-Mumps-IgM, ELISA-Mumps-IgG, Anti-Mumps Virus ELISA-IgM, and Anti-Mumps Virus ELISA-IgG, a blood serum samples from patients (n = 41) with a diagnosis mumps? were tested in dynamics to assess their sensitivity, specificity, and diagnostic effectiveness. Results. The clinical symptom dry mouth increased the chance of diagnosing mumps by 13.7 times, the presence of bilateral lesions of the salivary glands by 6.5 times, the increase in the level of diastase in the urine by 3.2 times. The coefficient of determination R2 was 61.1; the sensitivity was 93% and the specificity 67%; p 0.001. Diagnostic effectiveness of Anti-Mumps Virus ELISA-IgG test system was 84.4%, ELISA-Mumps-IgG 87.2%, and "VectoParotitis-IgG" 88.5%. Conclusions. Based on the combination of following clinical symptoms observed simultaneously in patient, of the general weakness, dry mouth, bilateral lesions of the salivary glands, an increase in the level of diastase in the urine, it is possible to establish a clinical diagnosis of mumps with a probability of 81%. The highest diagnostic effectiveness of domestically manufactured test systems for quantitation of IgG antibodies to mumps virus in sick people has been demonstrted.

Improved Immunogenicity of the Inactivated F Genotype Mumps Vaccine against Diverse Circulating Mumps Viruses in Mice

Mumps is an acute infectious disease caused by the mumps virus (MuV). Despite high global vaccination coverage, mumps outbreaks continue to occur, even in vaccinated populations. Therefore, we aimed to identify candidate vaccines that can induce an immunogenic response against diverse MuV genotypes with greater efficacy than the currently available options. Vaccine candidates were sourced using formalin-inactivated viral strains. The inactivated vaccines were administered to BALB/c mice (through a primer and booster dose administered after a three-week interval). We tested the neutralizing antibodies of the candidate vaccines against various MuV genotypes to determine their overall efficacy. The formalin-inactivated F genotype vaccine was found to have higher cross-neutralizing titers against genotypes F, H, and G as well as significant Th1 cytokines responses, IFN-γ, TNF-α, and IL-2 than the Jeryl Lynn (JL) vaccine. Our findings suggest that the inactivated F genotype mumps vaccine has higher immunogenicity than the JL vaccine against diverse circulating MuVs.

Immune responses of a CV-A16 live attenuated candidate strain and its protective effects in rhesus monkeys

Coxsackievirus A16 (CV-A16) is a major causative pathogen of hand, foot, and mouth diseases (HFMDs). The licensed HFMD vaccine targets EV-A71 without cross-protection against CV-A16. Thus, a CV-A16 vaccine is needed. In this study, the immunogenicity and protective efficacy of a live attenuated CV-A16 candidate, K168-8Ac, were evaluated in a rhesus monkey model. Four passages of this strain (P35, P50, P60, and P70) were administered to monkeys, and its protective effect was identified. The immunized monkeys were clinically asymptomatic, except for slight fever. Weak viraemia was observed, and two doses of vaccination were found to significantly reduce virus shedding. High levels of antibody responses were observed (1:1024–1:2048), along with a significant increase in plasma IL-8. The I.M. group showed a much stronger humoural immunity. Pathological damage was detected mainly in lung tissues, although thalamus, spinal cord, lymph nodes, and livers were involved. After the viral challenge, it was found that two doses of vaccine reduced virus shedding, and the degree of lung damage and the number of organs involved decreased as the passage number increased. Overall, a robust immune response and partial protection against CV-A16, triggered by the K168-8Ac strain, were demonstrated. This study provides valuable data for CV-A16 vaccine development.

Close the gap for routine mumps vaccination in Japan

Mumps is a vaccine-preventable disease. Because the mumps vaccine can cause aseptic meningitis in rare cases, this vaccine is not routine in Japan. This has led to low vaccine coverage and severe disease burden in Japan. The present review summarizes mumps epidemiology and vaccination and discusses effective future strategies to mitigate the current disease burden of mumps in Japan. Although a recent study reported that mumps vaccine coverage rates are improving in Japan, current coverage rates are far below the optimal rate to suppress the ongoing epidemic, which has caused an average annual financial loss of 85 billion JPY between 2000 and 2016. Recent reports have demonstrated a much lower incidence of vaccine-induced aseptic meningitis in newly developed vaccines, especially when administered at 1 year of age. Cost-effectiveness studies suggest that routinization of the currently distributed domestic vaccine would be highly cost-effective. In addition, questionnaire surveillance data suggest that the majority of the Japanese population accepts the nominal risk of the vaccine when the proper information is provided. Finally, there are some successful programs in Japan that have attained high vaccine coverage rates with financial support from local governments. Taken together, these data suggest that the mumps vaccine should be immediately included in routine vaccines in Japan.

Safety and immunogenicity of an experimental live combination vaccine against enterovirus 71 and coxsackievirus A16 in rhesus monkeys

Enterovirus 71 (EV-A71) and Coxsackievirus A16 (CV-A16) are the two most common pathogens causing hand, foot, and mouth disease (HFMD). Previously, we obtained one candidate live attenuated strain each for EV-A71 and CV-A16; here, we evaluated the safety and immunogenicity of a combinedlive vaccine against EV-A71 and CV-A16 generated from these two candidate strains. Rhesus monkeys were intramuscularly treated with a live combinationvaccine against both EV-A71 and CV-A16 or with either vaccine alone. No fever or atypical clinical signs were observed in any animals. Monkeys vaccinated with the combinationlive vaccine presented no notable pathological changes in the brain, spinal cord, lung, and liver; in contrast, these regions showed inflammatory cell infiltration in monkeys treated with EV-A71 alone or CV-A16 alone. Weak viremia was detected in plasma after inoculation with the combinationvaccine; however, the duration of viral shedding in feces was increased. Biochemical studies revealed a slight increase in aspartate aminotransferase levels in monkeys inoculated with the live combination vaccine; however, histopathological findings did not attribute this change to liver damage. We also found that the live combinationvaccine induced a dual humoral immune response. Cytokine analysis indicated that the combined EV-A71/CV-A16 vaccine significantly down-regulated interleukin-8 production. Here, we have demonstrated that the live attenuated EV-A71/CV-A16 vaccine was safe and could trigger a dual specific immune response. However, its immune protection efficacy requires further investigation.