Evaluation of the Interactions between Mumps Virus and Guinea Pig.

Mumps is a highly contagious viral disease that can be prevented by vaccination. In the last decade, we have encountered repeated outbreaks of mumps in highly vaccinated populations, which call into question the effectiveness of available vaccines. Animal models are crucial for understanding virus-host interactions, and viruses such as mumps virus (MuV), whose only natural host is the human, pose a particular challenge. In our study, we examined the interaction between MuV and the guinea pig. Our results present the first evidence that guinea pigs of the Hartley strain can be infected in vivo after intranasal and intratesticular inoculation. We observed a significant viral replication in infected tissues up to 5 days following infection and induction of cellular and humoral immune responses as well as histopathological changes in infected lungs and testicles, without clinical signs of disease. Transmission of the infection through direct contact between animals was not possible. Our results demonstrate that guinea pigs and guinea pig primary cell cultures represent a promising model for immunological and pathogenetic studies of the complex MuV infection. IMPORTANCE Understanding of mumps virus (MuV) pathogenesis and the immune responses against MuV infection is limited. One of the reasons is the lack of relevant animal models. This study explores the interaction between MuV and the guinea pig. We demonstrated that all tested guinea pig tissue homogenates and primary cell cultures are highly susceptible to MuV infection and that α2,3-sialylated glycans (MuV cellular receptors) are being abundantly expressed at their surface. The virus remains in the guinea pig lungs and trachea for up to 4 days following intranasal infection. Although asymptomatic, MuV infection strongly activates both humoral and cellular immune response in infected animals and provides protection against virus challenge. Infection of the lungs and testicles after intranasal and intratesticular inoculation, respectively, is also supported by histopathological changes in these organs. Our findings give perspective for application of guinea pigs in research on MuV pathogenesis, antiviral response, and vaccine development and testing.

Unique Tropism and Entry Mechanism of Mumps Virus.

Mumps virus (MuV) is an important human pathogen that causes parotitis, orchitis, oophoritis, meningitis, encephalitis, and sensorineural hearing loss. Although mumps is a vaccine-preventable disease, sporadic outbreaks have occurred worldwide, even in highly vaccinated populations. MuV not only causes systemic infection but also has a unique tropism to glandular tissues and the central nervous system. In general, tropism can be defined by multiple factors in the viral life cycle, including its entry, interaction with host factors, and host-cell immune responses. Although the underlying mechanisms of MuV tropism remain to be fully understood, recent studies on virus-host interactions have provided insights into viral pathogenesis. This review was aimed at summarizing the entry process of MuV by focusing on the glycan receptors, particularly the recently identified receptors with a trisaccharide core motif, and their interactions with the viral attachment proteins. Here, we describe the receptor structures, their distribution in the human body, and the recently identified host factors for MuV and analyze their relationship with MuV tropism.

Mumps outbreak among fully vaccinated school-age children and young adults, Portugal 2019/2020.

On 16-17 January 2020, four suspected mumps cases were reported to the local Public Health Authorities with an epidemiological link to a local school and football club. Of 18 suspected cases identified, 14 were included in this study. Laboratory results confirmed mumps virus as the cause and further sequencing identified genotype G. Our findings highlight that even with a high MMR vaccine coverage, mumps outbreaks in children and young adults can occur. Since most of the cases had documented immunity for mumps, we hypothesise that waning immunity or discordant mumps virus strains are likely explanations for this outbreak.

Repeated introductions and intensive community transmission fueled a mumps virus outbreak in Washington State.

In 2016/2017, Washington State experienced a mumps outbreak despite high childhood vaccination rates, with cases more frequently detected among school-aged children and members of the Marshallese community. We sequenced 166 mumps virus genomes collected in Washington and other US states, and traced mumps introductions and transmission within Washington. We uncover that mumps was introduced into Washington approximately 13 times, primarily from Arkansas, sparking multiple co-circulating transmission chains. Although age and vaccination status may have impacted transmission, our data set could not quantify their precise effects. Instead, the outbreak in Washington was overwhelmingly sustained by transmission within the Marshallese community. Our findings underscore the utility of genomic data to clarify epidemiologic factors driving transmission and pinpoint contact networks as critical for mumps transmission. These results imply that contact structures and historic disparities may leave populations at increased risk for respiratory virus disease even when a vaccine is effective and widely used.

Mumps Orchitis: Clinical Aspects and Mechanisms.

The causative agent of mumps is a single-stranded, non-segmented, negative sense RNA virus belonging to the Paramyxoviridae family. Besides the classic symptom of painfully swollen parotid salivary glands (parotitis) in mumps virus (MuV)-infected men, orchitis is the most common form of extra-salivary gland inflammation. Mumps orchitis frequently occurs in young adult men, and leads to pain and swelling of the testis. The administration of MuV vaccines in children has been proven highly effective in reducing the incidence of mumps. However, a recent global outbreak of mumps and the high rate of orchitis have recently been considered as threats to male fertility. The pathogenesis of mumps orchitis remains largely unclear due to lack of systematic clinical data analysis and animal models studies. The alarming increase in the incidence of mumps orchitis and the high risk of the male fertility have thus become a major health concern. Recent studies have revealed the mechanisms by which MuV-host cells interact and MuV infection induces inflammatory responses in testicular cells. In this mini-review, we highlight advances in our knowledge of the clinical aspects and possible mechanisms of mumps orchitis.

The Amino Acid at Position 8 of the Proteolytic Cleavage Site of the Mumps Virus Fusion Protein Affects Viral Proteolysis and Fusogenicity.

The mumps virus (MuV) fusion protein (F) plays a crucial role for the entry process and spread of infection by mediating fusion between viral and cellular membranes as well as between infected and neighboring cells, respectively. The fusogenicity of MuV differs depending on the strain and might correlate with the virulence; however, it is unclear which mechanisms contribute to the differentiated fusogenicity. The cleavage motif of MuV F is highly conserved among all strains, except the amino acid residue at position 8 (P8) that shows a certain variability with a total of four amino acid variants (leucine [L], proline [P], serine [S], and threonine [T]). We demonstrate that P8 affects the proteolytic processing and the fusogenicity of MuV F. The presence of L or S at P8 resulted in a slower proteolysis of MuV F by furin and a reduced ability to mediate cell-cell fusion. However, virus-cell fusion was more efficient for F proteins harboring L or S at P8, suggesting that P8 contributes to the mechanism of viral spread: P and T enable a rapid spread of infection by cell-to-cell fusion, whereas viruses harboring L or S at P8 spread preferentially by the release of infectious viral particles. Our study provides novel insights into the fusogenicity of MuV and its influence on the mechanisms of virus spread within infected tissues. Assuming a correlation between MuV fusogenicity and virulence, sequence information on the amino acid residue at P8 might be helpful to estimate the virulence of circulating and emerging strains.IMPORTANCE Mumps virus (MuV) is the causative agent of the highly infectious disease mumps. Mumps is mainly associated with mild symptoms, but severe complications such as encephalitis, meningitis, or orchitis can also occur. There is evidence that the virulence of different MuV strains and variants might correlate with the ability of the fusion protein (F) to mediate cell-to-cell fusion. However, the relation between virulence and fusogenicity or the mechanisms responsible for the varied fusogenicity of different MuV strains are incompletely understood. Here, we focused on the amino acid residue at position 8 (P8) of the proteolytic cleavage site of MuV F, because this amino acid residue shows a striking variability depending on the genotype of MuV. The P8 residue has a significant effect on the proteolytic processing and fusogenicity of MuV F and might thereby determine the route of viral spread within infected tissues.

Molecular epidemiology of mumps viruses in the Netherlands, 2017-2019.

Mumps cases continue to occur, also in countries with a relatively high vaccination rate. The last major outbreaks of mumps in the Netherlands were in 2009-2012 and thereafter, only small clusters and single cases were reported. Molecular epidemiology can provide insights in the circulation of mumps viruses. The aims of the present study were to analyze the molecular epidemiology of mumps viruses in the Netherlands in 2017-2019 and to compare the phylogenetic trees built from sequence data of near complete mumps virus genomes or from the SH gene and non-coding regions (SH+NCRs). To this end, Sanger sequence data from SH+NCRs were analyzed from 82 mumps genotype G viruses. In addition, near complete genomes were obtained from 10 mumps virus isolates using next-generation sequencing. Analysis of SH+NCRs sequences of mumps genotype G viruses revealed the presence of two major genetic lineages in the Netherlands, which was confirmed by analysis of near complete genomes. Comparison of phylogenetic trees built with SH+NCRs or near complete genomes indicated that the topology was similar, while somewhat longer branches were present in the phylogenetic tree with near complete genomes. These results confirm that analysis of SH + NCRs sequence data is a useful approach for molecular surveillance. Furthermore, data from recent mumps genotype G viruses might indicate (intermittent) circulation of mumps genotype G viruses in the Netherlands in 2017-2019.

Effect of change in cell substrate on the critical quality attributes of L-Zagreb Mumps vaccine manufactured using parallel plate bioreactor.

Leningrad-Zagreb strain of mumps vaccine virus was grown on two different cell substrates viz. MRC-5 cells and Vero cells besides its original cell substrate i.e. Chicken Embryo Cells. Homogeneous virus pools prepared from each set of experiments were then lyophilized as per standard in-house protocol. Critical Quality Attributes (CQAs) such as the titer of the bulk vaccine and potency and stability of the lyophilized vaccine were then estimated using the CCID50 method to understand the lyophilization losses and thermal losses respectively in the vaccine. Another CQA viz. the genetic homogeneity of the vaccine was also tested using the single base extension method for identifying the nucleotides present at the three known locations of single nucleotide polymorphism (SNP). Comparison of CQA results across different cell substrates indicated encouraging results for Vero cell grown L-Zagreb virus compared to the MRC-5 cells grown L-Zagreb mumps virus. Significant improvement in productivity was also observed in the dynamic culture conditions compared to the static culture conditions. Progressive work in this research area can lead to development of a cGMP manufacturing process for mumps vaccine with easy scale up potential in future.

Caracterización clínica y etiológica de los casos de parotiditis en un servicio de urgencias / Clinical features and origin of cases of parotiditis in an emergency department

No disponible

Waning immunity and re-emergence of measles and mumps in the vaccine era.

Vaccine-preventable diseases (VPD) including measles and mumps have been re-emerging in countries with sustained high vaccine coverage. For mumps, waning immunity has been recognized as a major contributor to recent outbreaks. Although unvaccinated individuals account for most cases in recent measles outbreaks, the role of immune waning remains unclear. Accumulating serological and epidemiological evidence suggests that natural immunity induced by infection may be more durable compared to vaccine-induced immunity. As the proportion of population immunity via vaccination gradually increases and boosting through natural exposures becomes rare, risk of outbreaks may increase. Mechanistic insights into the coupled immuno-epidemiological dynamics of waning and boosting will be important to understand optimal vaccination strategies to combat VPD re-emergence and achieve eradication.

Effects of meteorological factors on the incidence of mumps and models for prediction, China.

BACKGROUND: Mumps is an acute respiratory infectious disease with obvious regional and seasonal differences. Exploring the impact of climate factors on the incidence of mumps and predicting its incidence trend on this basis could effectively control the outbreak and epidemic of mumps. METHODS: Considering the great differences of climate in the vast territory of China, this study divided the Chinese mainland into seven regions according to the administrative planning criteria, data of Mumps were collected from the China Disease Prevention and Control Information System, ARIMA model and ARIMAX model with meteorological factors were established to predict the incidence of mumps. RESULTS: In this study, we found that precipitation, air pressure, temperature, and wind speed had an impact on the incidence of mumps in most regions of China and the incidence of mumps in the north and southwest China was more susceptible to climate factors. Considering meteorological factors, the average relative error of ARIMAX model was 10.87%, which was lower than ARIMA model (15.57%). CONCLUSIONS: Meteorology factors were the important factors which can affect the incidence of mumps, ARIMAX model with meteorological factors could better simulate and predict the incidence of mumps in China, which has certain reference value for the prevention and control of mumps.

Large-Scale Expression and Purification of Mumps Virus Hemagglutinin-Neuraminidase for Structural Analyses and Glycan-Binding Assays.

Many viruses utilize cell-surface glycans as receptors for host cell entry. Viral surface glycoproteins specifically interact with glycan motifs, which strongly contributes to viral tropism. Recently, the interactions between host cell glycan receptors and the mumps virus (MuV) hemagglutinin-neuraminidase (MuV-HN) protein were characterized by determining the co-crystal structure of MuV-HN in complex with glycan receptors. Here, we describe protocols for large-scale expression, purification and crystallization of MuV-HN proteins for structural analyses and glycan-binding assays with the overarching goal of investigating glycan-protein interactions.

Measles and mumps outbreaks in Lebanon: trends and links.

BACKGROUND: Lebanon has experienced several measles and mumps outbreaks in the past 20 years. In this article, a case-based surveillance of both measles and mumps outbreaks in Lebanon was carried out in an attempt to outline factors contributing to the failure of elimination plans and to provide potential solutions. The relationship between the outbreaks of both diseases was described and explored. METHODS: A retrospective descriptive study of confirmed cases of measles and mumps in Lebanon between 2003 and 2018 collected from the Lebanese Ministry of Public Health Epidemiological Surveillance Unit public database was carried out. The information collected was graphically represented taking into consideration dates of reported cases, age groups affected, and vaccination status. RESULTS: The mean number of measles cases was 150.25 cases/year in the 1-4 years age group, 87 cases/year in individuals aging between 5 and 14, and 63.68 cases/year in those > 14 years old. In the latter group, only 18.05% were unvaccinated. The mean number of mumps cases was 30.4 cases/year in the < 4 year age group and 53.8 cases/year in the 10-19 years age group. During the study period, every spike in measles cases was followed by a similar spike in mumps. 9.66% of measles cases occurred in individuals who received at least 2 doses of the vaccine, 52.26% in the unvaccinated, and 38% in those whose vaccination status was undetermined. CONCLUSIONS: Measles in Lebanon is a disease of the pediatric population, but adults remain at risk. Outbreaks of mumps followed those of measles and were mainly among adolescents. Presence of a large number of Syrian refugees in the country may further complicate the situation. Vaccination activities need to be intensified.

Combining genomics and epidemiology to track mumps virus transmission in the United States.

Unusually large outbreaks of mumps across the United States in 2016 and 2017 raised questions about the extent of mumps circulation and the relationship between these and prior outbreaks. We paired epidemiological data from public health investigations with analysis of mumps virus whole genome sequences from 201 infected individuals, focusing on Massachusetts university communities. Our analysis suggests continuous, undetected circulation of mumps locally and nationally, including multiple independent introductions into Massachusetts and into individual communities. Despite the presence of these multiple mumps virus lineages, the genomic data show that one lineage has dominated in the US since at least 2006. Widespread transmission was surprising given high vaccination rates, but we found no genetic evidence that variants arising during this outbreak contributed to vaccine escape. Viral genomic data allowed us to reconstruct mumps transmission links not evident from epidemiological data or standard single-gene surveillance efforts and also revealed connections between apparently unrelated mumps outbreaks.

Identification of Naturally Processed Mumps Virus Epitopes by Mass Spectrometry: Confirmation of Multiple CD8+ T-Cell Responses in Mumps Patients.

BACKGROUND: The re-emergence of mumps among vaccinated young adults has become a global issue. Besides waning of antibody responses, suboptimal induction of T-cell responses may reduce protection. In a recent study, we observed a dominant polyfunctional CD8+ T-cell response after natural mumps virus (MuV) infection that was not present after vaccination. Unraveling the MuV epitope repertoire can provide insight in the specificity, functionality, and breadth of the T-cell response against MuV. METHODS: Peptides were eluted from human leukocyte antigen (HLA) class I molecules of MuV-infected cells and characterized by advanced mass spectrometry. Selected identified MuV peptides were tested for in vitro and ex vivo immunogenicity. RESULTS: In this study, we identified a broad landscape of 83 CD8+ T-cell epitopes of MuV, 41 of which were confirmed based on synthetic peptide standards. For 6 epitopes, we showed induction of an HLA-A*02-restriced CD8+ T-cell response. Moreover, robust T-cell responses against 5 selected MuV epitopes could be detected in all tested mumps patients using peptide/HLA-A*02:01 dextramers. CONCLUSIONS: The identified CD8+ T-cell epitopes will help to further characterize MuV-specific T-cell immunity after natural MuV infection or vaccination. These MuV epitopes may provide clues for a better understanding of, and possibly for preventing, mumps vaccine failure.We identified for the first time 41 mumps virus (MuV)-specific HLA-A*02 epitopes. For 6 epitopes, CD8+ T-cell responses were confirmed in T cells derived from several mumps cases, and MuV-specific CD8+ T cells could be identified by peptide/dextramer staining.

Long-term Immunogenicity of Measles Vaccine: An Italian Retrospective Cohort Study.

BACKGROUND: Levels of antibodies induced by the measles virus-containing vaccine have been shown to decline over time, but there is no formal recommendation about testing immunized subjects (in particular, healthcare workers [HCWs]) to investigate the persistence of measles immunoglobulin G (IgG). METHODS: This study aims to evaluate the long-term immunogenicity of measles vaccine in a sample of medical students and residents of the University of Bari who attended the Hygiene Department for a biological risk assessment (April 2014-June 2018). RESULTS: Two thousand immunized (2 doses of measles-mumps-rubella [MMR] vaccine) students and residents were tested; 305 of these (15%) did not show protective anti-measles IgG. This proportion was higher among subjects who received vaccination at ≤15 months (20%) than in those who received vaccination at 16-23 months (17%) and at ≥24 months (10%) (P < .0001). After an MMR vaccine booster dose, we noted a seroconversion of 74% of seronegative HCWs. The overall seroconversion rate after a second dose (booster) was 93%. No serious adverse events were noted after the booster doses. CONCLUSIONS: An important proportion of subjects immunized for measles do not show a protective IgG titer in the 10 years after vaccination. Our management strategy seems consistent with the purpose of evidencing immunological memory.

A Single Point Mutation in the Mumps V Protein Alters Targeting of the Cellular STAT Pathways Resulting in Virus Attenuation.

Mumps virus (MuV) is a neurotropic non-segmented, negative-stranded, enveloped RNA virus in the Paramyxovirus family. The 15.4 kb genome encodes seven genes, including the V/P, which encodes, among other proteins, the V protein. The MuV V protein has been shown to target the cellular signal transducer and activator of transcription proteins STAT1 and STAT3 for proteasome-mediated degradation. While MuV V protein targeting of STAT1 is generally accepted as a means of limiting innate antiviral responses, the consequence of V protein targeting of STAT3 is less clear. Further, since the MuV V protein targets both STAT1 and STAT3, specifically investigating viral antagonism of STAT3 targeting is challenging. However, a previous study reported that a single amino acid substitution in the MuV V protein (E95D) inhibits targeting of STAT3, but not STAT1. This provided us with a unique opportunity to examine the specific role of STAT 3 in MuV virulence in an in vivo model. Here, using a clone of a wild type MuV strain expressing the E95D mutant V protein, we present data linking inhibition of STAT3 targeting with the accelerated clearance of the virus and reduced neurovirulence in vivo, suggesting its role in promoting antiviral responses. These data suggest a rational approach to virus attenuation that could be exploited for future vaccine development.

Mumps: MMR vaccination and genetic diversity of mumps virus, 2007-2011 in Catalonia, Spain.

BACKGROUND: Mumps is a vaccine-preventable disease but outbreaks have been reported in persons vaccinated with two doses of MMR vaccine. The objective was to describe the demographic features, vaccination effectiveness and genetic mumps virus diversity among laboratory-confirmed cases between 2007 and 2011 in Catalonia. METHODS: Cases and outbreaks of mumps notified to the notifiable diseases system of Catalonia between 2007 and 2011 retrospectively registered were included. Public health care centres provided written immunization records to regional public health staff to determine the vaccination history. Saliva and serum specimens were collected from suspected cases for laboratory-confirmation using real-time reverse-transcriptase PCR (rtRT-PCR) or serological testing. Phylogenetic analysis of the complete SH gene (316 nucleotides) and complete coding HN protein (1749 nucleotides) sequences was made. Categorical variables were compared using the Chi-square or Fisher's tests and continuous variables using the Student test. Vaccination effectiveness by number of MMR doses was estimated using the screening method. RESULTS: During the study period, 581 confirmed cases of mumps were notified (incidence rate 1.6 cases/100,000 persons-year), of which 60% were male. Three hundred sixty-four laboratory-confirmed cases were reported, of which 44% were confirmed by rtRT-PCR. Of the 289 laboratory-confirmed cases belonging to vaccination cohorts, 33.5% (97) had received one dose of MMR vaccine and 50% (145) two doses. Based on phylogenetic analyses of 316-nucleotide and 174-nucleotide SH sequences, the viruses belonging to viral genotypes were: genotype G (126), genotype D (23), genotype H (2), genotype F (2), genotype J (1), while one remained uncharacterized. Amino acid differences were detected between circulating strains and the Jeryl Lynn vaccine strains, although the majority of amino acid substitutions were genotype-specific. Fifty-one outbreaks were notified that included 324 confirmed mumps cases. Genotype G was the most frequent genotype detected. The family (35%), secondary schools (25%) and community outbreaks (18%) were the most frequent settings. CONCLUSIONS: Our study shows that genotype G viruses are the most prevalent in Catalonia. Most cases occurred in people who had received two doses of MMR, suggesting inadequate effectiveness of the Jeryl Lynn vaccine strain. The possible factors related are discussed.

Decreased humoral immunity to mumps in young adults immunized with MMR vaccine in childhood.

In the past decade, multiple mumps outbreaks have occurred in the United States, primarily in close-contact, high-density settings such as colleges, with a high attack rate among young adults, many of whom had the recommended 2 doses of mumps-measles-rubella (MMR) vaccine. Waning humoral immunity and the circulation of divergent wild-type mumps strains have been proposed as contributing factors to mumps resurgence. Blood samples from 71 healthy 18- to 23-year-old college students living in a non-outbreak area were assayed for antibodies and memory B cells (MBCs) to mumps, measles, and rubella. Seroprevalence rates of mumps, measles, and rubella determined by IgG enzyme-linked immunosorbent assay (ELISA) were 93, 93, and 100%, respectively. The index standard ratio indicated that the concentration of IgG was significantly lower for mumps than rubella. High IgG avidity to mumps Enders strain was detected in sera of 59/71 participants who had sufficient IgG levels. The frequency of circulating mumps-specific MBCs was 5 to 10 times lower than measles and rubella, and 10% of the participants had no detectable MBCs to mumps. Geometric mean neutralizing antibody titers (GMTs) by plaque reduction neutralization to the predominant circulating wild-type mumps strain (genotype G) were 6-fold lower than the GMTs against the Jeryl Lynn vaccine strain (genotype A). The majority of the participants (80%) received their second MMR vaccine ≥10 years prior to study participation. Additional efforts are needed to fully characterize B and T cell immune responses to mumps vaccine and to develop strategies to improve the quality and durability of vaccine-induced immunity.