Mumps Vaccines: Current Challenges and Future Prospects

Exploration of microRNAs as transcriptional regulator in mumps virus infection through computational studies

Mumps is a common childhood infection caused by the mumps virus (MuV). Aseptic meningitis and encephalitis are usual symptoms of mumps together with orchitis and oophoritis that can arise in males and females, respectively. We have used computational tools: RNA22, miRanda and psRNATarget to predict the microRNA-mRNA binding sites to find the putative microRNAs playing role in the host response to mumps virus infection. Our computational studies indicate that hsa-mir-3155a is most likely involved in mumps infection. This was further investigated by the prediction of binding sites of hsa-mir-3155a to the MuV genome. Additionally, structure prediction using MC-Fold and MC-Sym, respectively has been applied to predict the 3D structures of miRNA and mRNA. The miRNA-mRNA interaction profile between has been confirmed through molecular docking simulation studies. Taken together, the putative miRNA (hsa_miR_6794_5p) has been found to be most likely involved in the regulation of transcriptional activity in the MuV infection.

Three SARS-CoV-2 spike protein variants delivered intranasally by measles and mumps vaccines are broadly protective

As the new SARS-CoV-2 Omicron variants and subvariants emerge, there is an urgency to develop intranasal, broadly protective vaccines. Here, we developed highly efficacious, intranasal trivalent SARS-CoV-2 vaccine candidates (TVC) based on three components of the MMR vaccine: measles virus (MeV), mumps virus (MuV) Jeryl Lynn (JL1) strain, and MuV JL2 strain. Specifically, MeV, MuV-JL1, and MuV-JL2 vaccine strains, each expressing prefusion spike (preS-6P) from a different variant of concern (VoC), were combined to generate TVCs. Intranasal immunization of IFNAR1-/- mice and female hamsters with TVCs generated high levels of S-specific serum IgG antibodies, broad neutralizing antibodies, and mucosal IgA antibodies as well as tissue-resident memory T cells in the lungs. The immunized female hamsters were protected from challenge with SARS-CoV-2 original WA1, B.1.617.2, and B.1.1.529 strains. The preexisting MeV and MuV immunity does not significantly interfere with the efficacy of TVC. Thus, the trivalent platform is a promising next-generation SARS-CoV-2 vaccine candidate.

Epidemiologic and clinical updates on viral infections in Saudi Arabia

In the past two decades, the world has witnessed devastating pandemics affecting the global healthcare infrastructure and disrupting society and the economy worldwide. Among all pathogens, viruses play a critical role that is associated with outbreaks due to their wide range of species, involvement of animal hosts, easily transmitted to humans, and increased rates of infectivity. Viral disease outbreaks threaten public health globally due to the challenges associated with controlling and eradicating them. Implementing effective viral disease control programs starts with ongoing surveillance data collection and analyses to detect infectious disease trends and patterns, which is critical for maintaining public health. Viral disease control strategies include improved hygiene and sanitation facilities, eliminating arthropod vectors, vaccinations, and quarantine. The Saudi Ministry of Health (MOH) and the Public Health Authority (also known as Weqayah) in Saudi Arabia are responsible for public health surveillance to control and prevent infectious diseases. The notifiable viral diseases based on the Saudi MOH include hepatitis diseases, viral hemorrhagic fevers, respiratory viral diseases, exanthematous viral diseases, neurological viral diseases, and conjunctivitis. Monitoring trends and detecting changes in these viral diseases is essential to provide proper interventions, evaluate the established prevention programs, and develop better prevention strategies. Therefore, this review aims to highlight the epidemiological updates of the recently reported viral infections in Saudi Arabia and to provide insights into the recent clinical treatment and prevention strategies.

Immunogenicity and Cross-Protection Efficacy of a Genotype F-Derived Attenuated Virus Vaccine Candidate against Mumps Virus in Mice

Mumps virus (MuV) causes an acute contagious human disease characterized by swelling of the parotid glands. Despite the near elimination of mumps in many countries, the disease has recurred, even in vaccinated populations, especially adolescents. Immunization effectivity of the genotype A vaccine strain Jeryl Lynn (JL) is declining as genotype A is no longer predominant; therefore, a new vaccine strain and booster vaccine are required. We generated a cell culture-adapted MuV genotype F called F30 and evaluated its immunogenicity and cross-protective activity against diverse genotypes. F30 genome nucleotide sequence determination revealed changes in the NP, L, SH, and HN genes, leading to five amino acid changes compared to a minimally passaged stock (F10). F30 showed delayed growth, smaller plaque size in Vero cells, and lower neurotoxicity in neonatal mice than F10. Furthermore, F30 was immunogenic to other genotypes, including the JL vaccine strain, with higher efficacy than that of JL for homologous and heterologous immunization. Further, F30 exhibited cross-protective immunity against MuV genotypes F and G in Ifnar-/- mice after a third immunization with F30 following two doses of JL. Our data suggest that the live-attenuated virus F30 could be an effective booster vaccine to control breakthrough infections and mumps epidemics.

Booster doses of an inactivated F genotype mumps vaccine enhance immunogenicity in mice

The mumps virus (MuV) causes a highly contagious human disease characterized by swelling of the parotid glands. Although the administration of an attenuated Jeryl Lynn (JL) MuV vaccine shows efficacy in reducing the incidence of MuV infection, sporadic mumps outbreaks still occur in vaccinated populations. We have previously established that an inactivated F genotype mumps vaccine has a higher neutralizing antibody titer against diverse circulating mumps viruses in mice. Here, we aimed to develop a vaccination strategy to enhance the immune response for MuV and assess the effects of heterologous vaccination compared with homologous approaches. We administered an inactivated F genotype mumps vaccine booster following a homologous prime-boost regime and compared its efficacy with three doses of homologous JL vaccine in mice. We demonstrated robust stimulation of neutralizing antibodies and cellular immune response of interferon-γ-secreting cytotoxic T cells following administration of an inactivated F genotype mumps vaccine booster after a homologous prime-boost regime with JL. Compared with the homologous prime-boost regime, this heterologous prime-boost regime showed protective efficacy against the F genotype of MuV. These findings suggest that the heterologous vaccination strategy based on the administration of an inactivated F genotype mumps vaccine provides more effective cross-protection against circulating wild-type mumps viruses than homologous vaccination.

Prenatal Exposure to Poly- and Perfluoroalkyl Substances (2009-2014) and Vaccine Antibody Titers of Measles, Mumps, Rubella, and Varicella in Children Four to Eight Years Old from the Healthy Start Cohort

BACKGROUND

Prenatal exposures to certain poly- and perfluoroalkyl substances (PFAS) are associated with reduced humoral responses to some childhood immunizations.

OBJECTIVE

We estimated associations between prenatal PFAS exposure and child antibody titers for measles, mumps, rubella (MMR), and varicella after immunization.

METHODS

We measured serum antibody titers of 145 children (4-8 y old) enrolled in the Healthy Start cohort in Colorado, whose mothers had PFAS quantified mid-pregnancy (2009-2014). We used linear and logistic regression models to assess the relationship between five PFAS detected in > 65 % of mothers and continuous or non-high-censored ("low") antibody titers and quantile g-computation to evaluate the overall effect of the PFAS mixture.

RESULTS

Median concentrations of individual PFAS were at or below the median reported among females in the United States. After receiving two vaccine doses, seropositive levels of antibodies were detected among most (93%-100%) children. Each log-unit increase in perfluorononanoate was associated with 2.09 [95% confidence interval (CI): 1.13, 3.87] times higher odds of a low measles titer, and each log-unit increase in perfluorooctanoate was associated with 2.46 (95% CI: 1.28, 4.75) times higher odds of a low mumps titer. Odds ratios for all other PFAS were elevated, but CIs included the null. Each quartile increase in the PFAS mixture was associated with 1.35 (95% CI: 0.80, 2.26) times higher odds of a low measles titer and 1.44 (95% CI: 0.78, 2.64) times higher odds of a low mumps titer. No significant associations were observed between PFAS and varicella or rubella antibodies. In stratified analyses, associations were negative among female children, except for perfluorohexane sulfonate and varicella, whereas they were positive among males.

DISCUSSION

Some prenatal PFAS were associated with lower antibody titers among fully immunized children. The potential for immunotoxic effects of PFAS requires further investigation in a larger study, because exposure is ubiquitous globally. https://doi.org/10.1289/EHP12863.

Mumps vaccine hesitancy: Current evidence and an evidence-based campaign in Japan

BACKGROUND

Mumps is still endemic in Japan because mumps vaccination is voluntary. In this study, we investigated associations of parental socioeconomic status, family structure, and knowledge/belief about mumps and mumps vaccine with parental decision to vaccinate their children. We also evaluated effectiveness of a campaign based on survey results.

METHODS

We conducted a cross-sectional survey of parents with children aged 1-6 years attending preschools or kindergartens in Tokamachi City, Japan. We assessed the association of parental factors with their decision to vaccinate their children using multivariable logistic regression analyses. We designed a campaign based on the survey results, and compared the number of annual vaccinations at Tokamachi Hospital per the child population aged 1-6 years in Tokamachi City before and after the campaign using a trend test.

RESULTS

In total, 1391 of 1617 (86%) eligible parents completed the survey. Among these parents, 229 (16%) vaccinated their children. In multivariable analyses, higher parental education [odds ratio (OR) = 2.21; 95% CI, 1.59-3.08; P < 0.001], greater knowledge about mumps and the mumps vaccine (OR = 1.88; 95% CI, 1.60-2.21; P < 0.001), and living without grandparents (OR = 1.44; 95% CI, 1.05-1.99; P = 0.024) were significantly associated with parental decision to vaccinate their children. The number of annual vaccinations per the child population significantly increased following the campaign (P < 0.001).

CONCLUSION

Our study showed several sociodemographic factors significantly associated with mumps vaccination. Further research is needed to examine the relevance of our findings to the uptake of other voluntary vaccines among children.

A critical overview of current progress for COVID-19: development of vaccines, antiviral drugs, and therapeutic antibodies

The novel coronavirus disease (COVID-19) pandemic remains a global public health crisis, presenting a broad range of challenges. To help address some of the main problems, the scientific community has designed vaccines, diagnostic tools and therapeutics for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The rapid pace of technology development, especially with regard to vaccines, represents a stunning and historic scientific achievement. Nevertheless, many challenges remain to be overcome, such as improving vaccine and drug treatment efficacies for emergent mutant strains of SARS-CoV-2. Outbreaks of more infectious variants continue to diminish the utility of available vaccines and drugs. Thus, the effectiveness of vaccines and drugs against the most current variants is a primary consideration in the continual analyses of clinical data that supports updated regulatory decisions. The first two vaccines granted Emergency Use Authorizations (EUAs), BNT162b2 and mRNA-1273, still show more than 60% protection efficacy against the most widespread current SARS-CoV-2 variant, Omicron. This variant carries more than 30 mutations in the spike protein, which has largely abrogated the neutralizing effects of therapeutic antibodies. Fortunately, some neutralizing antibodies and antiviral COVID-19 drugs treatments have shown continued clinical benefits. In this review, we provide a framework for understanding the ongoing development efforts for different types of vaccines and therapeutics, including small molecule and antibody drugs. The ripple effects of newly emergent variants, including updates to vaccines and drug repurposing efforts, are summarized. In addition, we summarize the clinical trials supporting the development and distribution of vaccines, small molecule drugs, and therapeutic antibodies with broad-spectrum activity against SARS-CoV-2 strains.

A highly efficacious live attenuated mumps virus-based SARS-CoV-2 vaccine candidate expressing a six-proline stabilized prefusion spike

With the rapid increase in SARS-CoV-2 cases in children, a safe and effective vaccine for this population is urgently needed. The MMR (measles/mumps/rubella) vaccine has been one of the safest and most effective human vaccines used in infants and children since the 1960s. Here, we developed live attenuated recombinant mumps virus (rMuV)-based SARS-CoV-2 vaccine candidates using the MuV Jeryl Lynn (JL2) vaccine strain backbone. The soluble prefusion SARS-CoV-2 spike protein (preS) gene, stablized by two prolines (preS-2P) or six prolines (preS-6P), was inserted into the MuV genome at the P-M or F-SH gene junctions in the MuV genome. preS-6P was more efficiently expressed than preS-2P, and preS-6P expression from the P-M gene junction was more efficient than from the F-SH gene junction. In mice, the rMuV-preS-6P vaccine was more immunogenic than the rMuV-preS-2P vaccine, eliciting stronger neutralizing antibodies and mucosal immunity. Sera raised in response to the rMuV-preS-6P vaccine neutralized SARS-CoV-2 variants of concern, including the Delta variant equivalently. Intranasal and/or subcutaneous immunization of IFNAR1-/- mice and golden Syrian hamsters with the rMuV-preS-6P vaccine induced high levels of neutralizing antibodies, mucosal immunoglobulin A antibody, and T cell immune responses, and were completely protected from challenge by both SARS-CoV-2 USA-WA1/2020 and Delta variants. Therefore, rMuV-preS-6P is a highly promising COVID-19 vaccine candidate, warranting further development as a tetravalent MMR vaccine, which may include protection against SARS-CoV-2.

Immunogenicity of Mumps Virus Genotype G Vaccine Candidates in Jeryl Lynn-Immunized Mice

Mumps virus (MuV) causes a highly contagious human disease characterized by the enlargement of the parotid glands. In severe cases, mumps can lead to neurological complications such as aseptic meningitis and encephalitis. Vaccination with the attenuated Jeryl Lynn (JL) MuV vaccine has dramatically reduced the incidence of MuV infection. Recently, large outbreaks have occurred in vaccinated populations. The vaccine strain JL was generated from genotype A, while most current circulating strains belong to genotype G. In this study, we examined the immunogenicity and longevity of genotype G-based vaccines. We found that our recombinant genotype G-based vaccines provide robust neutralizing titers toward genotype G for up to 1 year in mice. In addition, we demonstrated that a third dose of a genotype G-based vaccine following two doses of JL immunization significantly increases neutralizing titers toward the genotype G strain. Our data suggest that after two doses of JL vaccination, which most people have received, a third dose of a genotype G-based vaccine can generate immunity against a genotype G strain. IMPORTANCE At present, most individuals have received two doses of the measles, mumps, and rubella (MMR) vaccine, which contains genotype A mumps vaccine. One hurdle in developing a new mumps vaccine against circulating genotype G virus is whether the new genotype G vaccine can generate immunity in humans that are immunized against genotype A virus. This work demonstrates that a novel genotype G-based vaccine can be effective in animals which received two doses of genotype A-based vaccine, suggesting that the lead genotype G vaccine may induce anti-G immunity in humans who have received two doses of the current vaccine, providing support for testing this vaccine in humans.

Mumps outbreak in university students: first detection of mumps virus genotype F in Borneo

BACKGROUND

In October 2016, a mumps outbreak occurred among the students living in the on-campus dormitory of a public university located in Kota Kinabalu, Sabah, Malaysia. This study aimed to investigate the outbreak and identify the genotype of the mumps virus (MuV) strain that was involved in the outbreak.

MAIN BODY

During the outbreak, one 21-year-old and four 20-year-old males staying in the same dormitory building were reported to have developed symptoms of mumps. Of these, two students were available during the investigation for sample collection to detect MuV by reverse transcription polymerase chain reaction (RT-PCR) of the 639-bp fragment encompassing the entire small hydrophobic (SH) gene. Nucleotide sequencing of the amplicon and phylogenetic analysis using the neighbor-joining method was performed to determine the MuV genotype. Of the two buccal swab samples, one was positive for MuV. The MuV strain in this sample belonged to genotype F and it was clustered together with genotype F strains from China with 96.84-99.68% nucleotide identity.

CONCLUSIONS

Genotype F has limited circulation and is endemic in mainland China. Genotype F strains occasionally reported from other countries were epidemiologically linked to China. This study is the first to report a case of genotype F MuV in Malaysia and no epidemiological link could be established with mainland China. The results provide important information that can assist in strategic planning to improve the prevention and control of mumps infection in Malaysia.

Antibody Levels at 3-Years Follow-Up of a Third Dose of Measles-Mumps-Rubella Vaccine in Young Adults

Mumps outbreaks and breakthrough infections of measles and rubella have raised concerns about waning of vaccine-induced immunity after two doses of measles-mumps-rubella (MMR) vaccination. In the present follow-up study, serum IgG antibodies against mumps, measles and rubella, as well as the functional neutralizing antibodies against both the mumps vaccine strain and mumps outbreak strains were measured longitudinally in young adults that received a third MMR (MMR3) dose. The mumps-specific IgG and virus neutralizing antibody levels at 3 years after vaccination were still elevated compared to pre-vaccination antibody levels, although the differences were smaller than at earlier timepoints. Interestingly, subjects with low antibody levels to mumps before vaccination benefited the most as they showed the strongest antibody increase after an MMR3 dose. Three years after an MMR3 dose, all subjects had antibody levels to measles and rubella above the internationally agreed antibody cutoff levels for clinical protection. Our data support the recommendation that an MMR3 dose may provide additional protection for those that have become susceptible to mumps virus infection during outbreaks. MMR3 also resulted in an increase in anti-measles and rubella antibody levels that lasted longer than might have been expected.

Genetic Analysis Reveals Differences in CD8+ T Cell Epitope Regions That May Impact Cross-Reactivity of Vaccine-Induced T Cells against Wild-Type Mumps Viruses

Nowadays, mumps is re-emerging in highly vaccinated populations. Waning of vaccine-induced immunity plays a role, but antigenic differences between vaccine and mumps outbreak strains could also contribute to reduced vaccine effectiveness. CD8⁺ T cells play a critical role in immunity to viruses. However, limited data are available about sequence variability in CD8⁺ T cell epitope regions of mumps virus (MuV) proteins. Recently, the first set of naturally presented human leukocyte antigen Class I (HLA-I) epitopes of MuV was identified by us. In the present study, sequences of 40 CD8⁺ T cell epitope candidates, including previously and newly identified, obtained from Jeryl–Lynn mumps vaccine strains were compared with genomes from 462 circulating MuV strains. In 31 epitope candidates (78%) amino acid differences were detected, and in 17 (43%) of the epitope candidates the corresponding sequences in wild-type strains had reduced predicted HLA-I-binding compared to the vaccine strains. These findings suggest that vaccinated persons may have reduced T cell immunity to circulating mumps viruses due to antigenic differences.

Waning immunity and potential asymptomatic infection in 3-7 years old children who received one dose of measles-mumps-rubella vaccine: A 4-year prospective study

BACKGROUND

Mumps outbreaks in adolescents who received two doses of measles-mumps-rubella vaccine (MMR) during childhood have been reported worldwide. In China, one dose of MMR administered in children aged among 18-24 months has a limited effect on the mumps epidemic. There are limited prospective studies evaluating the mumps immunity profile of children aged 3-7 years who received one dose of MMR. This study aimed to describe mumps immunity profile over a span of 4-years in kindergarten and primary school children.

METHODS

An observational, prospective study on one-dose MMR in children aged 3-7 years who underwent blood sample collection in 2015, 2016, and 2018 was conducted from 2015 to 2018. The seropositivity and geometric mean concentration of mumps IgG antibodies over time were analyzed.

RESULTS

A total of 3346 eligible children aged 3-7 years who underwent three rounds of blood sample collection were included. The overall seropositivity (79.6%) in 2015 was significantly higher than those recorded in 2016 (73.1%) and 2018 (71.4%). Approximately 11.6-15.9% of the participants were seropositive for mumps in 2015, and converted to negative in 2016. Meanwhile, 11.1-14.6% of the participants were seropositive for mumps in 2016, and the results converted to negative in 2018. Over 6.1-7.4% of the participants had asymptomatic infection from 2015 to 2016, while 9.0-9.9% of the participants were infected without clinical symptoms from 2016 to 2018.

CONCLUSIONS

Kindergarten and primary school children who only received one dose of MMR were at higher risk of developing mumps. Waning immunity, seronegative conversion, and asymptomatic infection coexist in children who received one dose MMR. Determining the optimal age for administering the second dose of MMR in children should be prioritized to improve the control and prevention of mumps in China.

Seroprevalence of anti-mumps virus IgG antibody titer and voluntary mumps vaccination coverage in young adults in Japan

In Japan, monovalent vaccine against mumps virus (MuV) infection was shifted to a voluntary basis vaccination due to the incidences of aseptic meningitis in the past. According to an analysis of a total of 409 participants aged 18-20 years, overall vaccination coverage rate was 48%. The mean anti-MuV IgG antibody titer of participants with medical history and more than two times vaccination was significantly higher than that in those without a medical history and unvaccinated and single vaccination, respectively. Seropositivity against MuV infection was >50% regardless of the number of vaccinations. Although these results suggest that seropositivity may persist due to asymptomatic infection, it is necessary to implement either a high vaccine coverage or routine vaccination for prevention of periodic mumps epidemics.

[Functional analysis of host factors involved in mumps virus propagation]

Mumps virus (MuV) is the causative agent of mumps, a common childhood illness characterized by fever and swelling of the salivary glands. Like other viral infections, a number of host proteins are thought to involve in MuV infection. We have shown the function of several host factors in MuV infection. The chaperone proteins, heat shock protein 70 (Hsp70) and Hsp90, interact with the P and L proteins that form the polymerase complex and function in the protein quality control of these viral proteins, and thus they are essential host factors in MuV RNA synthesis. The R2TP complex is a host factor that contributes to effective viral propagation by precise regulation of viral RNA synthesis and evasion of host immune responses, and Rab11 is a host factor involved in viral RNP trafficking to the plasma membrane. This article summarizes the functions of host factors involved in MuV infection based on our researches.