Wild type mumps viruses circulating in China establish a new genotype

Development of Improved Mumps Vaccine Candidates by Mutating Viral mRNA Cap Methyltransferase Sites in the Large Polymerase Protein

Although a live attenuated vaccine is available for controlling mumps virus (MuV), mumps still outbreaks frequently worldwide. The attenuated MuV vaccine strain S79 is widely used in mumps vaccination in China, but still with many shortcomings, among which the most prominent are the side effects and decreased immunity. Therefore, there is a need to further improve the safety and efficacy of the current MuV vaccine. In the present study, we further attenuated MuV S79 vaccine strain by inhibiting viral mRNA methyltransferase (MTase). We generated a panel of eight recombinant MuVs (rMuVs) carrying mutations in the MTase catalytic site or S-adenosylmethionine (SAM) binding site in the large (L) polymerase protein. These rMuVs are genetically stable and seven rMuVs are more attenuated in replication in cell culture and five rMuVs are more attenuated in replication in lungs of cotton rats compared with the parental vaccine strain S79. Importantly, cotton rats vaccinated with these seven rMuV mutants produced high levels of serum neutralizing antibodies and were completely protected against challenge with a wild-type MuV strain (genotype F). Therefore, our results demonstrate that alteration in the MTase catalytic site or SAM binding site in MuV L protein improves the safety or the immunogenicity of the MuV vaccine and thus mRNA cap MTase may be an effective target for the development of new vaccine candidates for MuV.

Epidemiological and Phylogenetic Analysis of Mumps Virus Isolated from 2016 to 2019 in Henan Province, China

Routine vaccination has proven to be highly effective in reducing the incidence of mumps. However, sporadic cases and/or mumps outbreaks have been reported in children and adolescents younger than 15 years of age, particularly among those aged 5-9 years. To explore the characteristics of such outbreaks in the Henan Province, clinical data of patients infected with mumps virus (MuV) were collected, and the isolated strains were phylogenetically analyzed. Of the total 426 samples analyzed, MuV RNA targeting the small hydrophobic (SH) gene was detected in 153 samples. MuV-positive cases in age groups <5 years, 5-9 years, 10-15 years, 16-19 years, and ≥20 years accounted for 1%, 17%, 12%, 2%, and 4% of the total number of cases, respectively. Phylogenetic analysis based on the SH gene sequences indicated that all of the isolated strains were of genotype F, and isolates in the same subcluster and with identical SH gene sequences tended to be derived from the same community or municipalities when analyzed alongside epidemiological data. In conclusion, the incidence of mumps in the Henan Province was high. The data provided in this study might promote further research in the clarification of the specific causes of mumps outbreaks, which can facilitate the implementation of effective prevention and control measures.

Evolutionary analysis of mumps viruses of genotype F collected in mainland China in 2001-2015

Mumps incidence in mainland China remains at a high level. Genotype F has been the predominant genotype of mumps virus (MuV) in the last 20 years in mainland China. To better understand the genetic characteristics of MuV in China, the sequences of the Small Hydrophobic (SH), Hemagglutinin-Neuraminidase (HN) and Fusion (F) genes of MuVs of genotype F collected during 2001-2015 were determined. The evolutionary rates of the HN and F genes were similar (0.5 × 10-3 substitutions/site/year) whereas the SH gene evolutionary rate was three times faster. The most recent common ancestor of genotype F was traced back to 1980. Four lineages were identified within HN and F MuV sequences. A phylogeographic analysis indicated that the genotype F viruses originally spread from the Liaoning and Shandong provinces followed by a spread to the South and East of China. This study provides important genetic baseline data for the development of prevention and control measures of mumps.

Genetic characterization of historical epidemic mumps viruses in northern Spain, 1987-1990

The mumps virus (MuV) is genetically diverse and is divided into 12 genotypes. The World Health Organization has recommended expanding virological surveillance for MuV, and therefore molecular characterization of circulating strains (i.e. genotypes) is increasingly performed. Nevertheless, little is known about the genotypes circulating before the massive vaccination of children and adolescents. The present study analyzed the strains causing the 1988-1989 mumps epidemic in the Basque Country, northern Spain, which occurred in the early vaccination period, before the endemic circulation of mumps virus was blocked. The epidemic reached an annual incidence rate of more than 400 cases/100,000 inhabitants, and caused a large number of cases of mumps meningitis. MuV RNA was amplified from the cerebrospinal fluid of 15 infected patients during the epidemic and from three more patients affected shortly before or after this epidemic (1987, early 1988 and 1990). Genotyping of the complete small hydrophobic gene (316 nucleotides), amplified in the 18 strains, as well as of the entire hemagglutinin-neuraminidase gene (1749 nucleotides), amplified in four strains, assigned all strains to genotype K, a genotype infrequently detected at present. Although the putative HN protein sequence differed by 4.8-5.5% in relation to Jeryl Lynn 5 strain (the main strain used in the vaccination program in this region), the vaccine was effective, and dramatically reduced the incidence of mumps over the following years. The presence of genotype K strains in Spain in the 1980s, together with their contemporary detection in Scandinavia, suggests that this genotype could have caused the Spanish epidemic and was also circulating widely in Europe at that time.

Safety and immunogenicity of a live attenuated mumps vaccine: a phase I clinical trial

BACKGROUND

Mumps, a communicable, acute and previously well-controlled disease, has had recent and occasional resurgences in some areas.

METHODS

A randomized, double-blind, controlled and multistep phase I study of an F-genotype attenuated mumps vaccine produced in human diploid cells was conducted. A total of 300 subjects were enrolled and divided into 4 age groups: 16-60 years, 5-16 years, 2-5 years and 8-24 months. The groups were immunized with one injection per subject. Three different doses of the F-genotype attenuated mumps vaccine, A (3.5 ± 0.25 logCCID50), B (4.25 ± 0.25 logCCID50) and C (5.0 ± 0.25 logCCID50), as well as a placebo control and a positive control of a licensed A-genotype vaccine (S79 strain) were used. The safety and immunogenicity of this vaccine were compared with those of the controls.

RESULTS

The safety evaluation suggested that mild adverse reactions were observed in all groups. No serious adverse event (SAE) was reported throughout the trial. The immunogenicity test showed a similar seroconversion rate of the neutralizing and ELISA antibody in the 2- to 5-year-old and 8- to 24-month-old groups compared with the seroconversion rate in the positive control. The GMT of the neutralizing anti-F-genotype virus antibodies in the vaccine groups was slightly higher than that in the positive control group.

CONCLUSIONS

The F-genotype attenuated mumps vaccine evaluated in this clinical trial was demonstrated to be safe and have effective immunogenicity vs. control.

Infection of mice, ferrets, and rhesus macaques with a clinical mumps virus isolate

In recent years, many mumps outbreaks have occurred in vaccinated populations worldwide. The reasons for these outbreaks are not clear. Animal models are needed to investigate the causes of outbreaks and to understand the pathogenesis of mumps virus (MuV). In this study, we have examined the infection of three animal models with an isolate of mumps virus from a recent outbreak (MuV-IA). We have found that while both ferrets and mice generated humoral and cellular immune responses to MuV-IA infection, no obvious signs of illness were observed in these animals; rhesus macaques were the most susceptible to MuV-IA infection. Infection of rhesus macaques via both intranasal and intratracheal routes with MuV-IA led to the typical clinical signs of mumps 2 weeks to 4 weeks postinfection. However, none of the infected macaques showed any fever or neurologic signs during the experimental period. Mumps viral antigen was detected in parotid glands by immunohistochemistry (IHC). Rhesus macaques represent the best animal model for the study of mumps virus pathogenesis.

Clinical features of mumps orchitis in vaccinated postpubertal males: a single-center series of 62 patients

Purpose

Although the measles-mumps-rubella vaccination covers most children against mumps in Korea, the development of mumps has been reported. However, the clinical manifestations of mumps orchitis in postpubertal vaccinated patients have never been investigated. Herein we report the clinical features of mumps orchitis in postpubertal vaccinated patients.

Materials and Methods

This study included a total of 62 postpubertal males who developed acute mumps orchitis from 2005 to 2010. The clinical manifestations such as the incubation period, febrile duration, and the mean duration of orchitis were retrospectively investigated. The laboratory and sonographic findings were also reviewed and compared with the features of previously reported cases of unvaccinated postpubertal mumps orchitis.

Results

The mean age of the 62 patients was 17.56 years (range, 15 to 29 years). All patients were serologically confirmed with acute mumps infection (positive immunoglobulin [Ig] M and negative or positive IgG). The mean incubation period was 5.39 days (range, 0 to 23 days), with a febrile duration of 1.8 days (range, 0.5 to 3 days), and a mean duration of orchitis of 4.96 days (range, 0 to 17 days). Sonography revealed unilateral orchitis in 58 patients (93.6%) and bilateral orchitis in only 6 (6.4%).

Conclusions

In our study, mumps orchitis in postpubertal vaccinated patients showed a relatively shorter febrile duration. In addition, less scrotal swelling and a lower incidence of bilaterality were found upon physical examination and ultrasonography. In the future, additional long-term follow-up is needed to determine the features of mumps orchitis in postpubertal vaccinated males, and an additional booster vaccination should be considered.

Characterization of mumps viruses circulating in Mongolia: identification of a novel cluster of genotype H

Although mumps virus is still causing annual epidemics in Mongolia, very few epidemiological and virological data have been reported. We describe here the first phylogenetic analysis data on the mumps viruses circulated in Mongolia in 2009. We detected 21 mumps virus cDNAs and obtained a virus isolate from 32 throat swabs of mumps patients in Ulaanbaatar, the capital of Mongolia. The phylogenetic analyses based on the 316 nucleotides of the small hydrophobic gene show that these sequences form a single cluster, with the closest relatedness to the viruses belonging to genotype H. According to the recommendation of the World Health Organization, Mongolian mumps viruses could be classified into a novel genotype because the divergence between new sequences and genotype H reference viruses is >5% (6.3 to 8.2%). However, additional analyses based on the fusion gene, the hemagglutinin-neuraminidase gene, and the whole-genome indicate that the divergences between the Mongolian isolate and other genotype H strains never exceed the within-genotype divergences of other genotypes. These results suggest that Mongolia strains should be included in genotype H and that the current criteria for mumps virus genotyping should be revised. We propose here that the Mongolian viruses should be classified as a new subgenotype termed H3. Since previous epidemiological studies suggested that genotypes H may be associated with central nervous system diseases, we evaluated the neurovirulence of the Mongolian isolate in the neonatal rat system. However, the virus does not exhibit prominent neurovirulence in rats.

Circulation of mumps virus genotypes in Spain from 1996 to 2007

Although the WHO recommends the use of genotyping as a tool for epidemiological surveillance for mumps, limited data on mumps virus (MV) genotype circulation that may be used to trace the patterns of virus spread are available. We describe the first complete series of data from Spain. The small hydrophobic region was sequenced from 237 MV-positive samples from several regions of Spain collected between 1996 and 2007. Six different genotypes were identified: A, C, D (D1), G (G1, G2), H (H1, H2), and J. Genotype H1 was predominant during the epidemic that occurred from 1999 to 2003 but was replaced by genotype G1 as the dominant genotype in the epidemic that occurred from 2005 to 2007. The same genotype G1 strain caused concomitant outbreaks in different parts of the world (the United States, Canada, and the United Kingdom). The remaining genotypes (genotypes A, C, D, and J) appeared in sporadic cases or small limited outbreaks. This pattern of circulation seems to reflect continuous viral circulation at the national level, despite the high rates of vaccine coverage.

Genetic characterization of RS-12 (S-12), an Iranian isolate of mumps virus, by sequence analysis and comparative genomics of F, SH, and HN genes

RS-12 mumps virus strain was isolated in 1986, in monkey kidney cells, from the throat-washing of an Iranian patient and developed to RS-12 vaccine by serial passage of the pathogen in MRC-5 cells. During the present study, an early passage RS-12 containing its virulent pathogenic phenotype, was characterized genetically. Its F, SH and HN genes were isolated by RT-PCR amplification and sequenced. It is quite evident that RS-12 belongs to genotype H, closely related to European strains but distinguishable from Asian strains. The deduced amino acid sequences of HN and F proteins that comprise immunogenic epitopes, were compared to other vaccine and wild strains. The multiple sequence alignment revealed that the RS-12 has isoleucine and aspartic acid at positions 269 and 523 of its F and HN proteins, respectively, which could differentiate RS-12 from other available sequences. This isolate has trivial variations in the major antigenic sites of HN protein. The frequency and pattern of F and HN glycosylation sites seems to be similar to most other strains. It seems that the mumps regional outbreak during 1986 in Iran was caused by genotype H and this strain has been spreading in countries surrounding the Caspian sea for over 17 years. These data support the previous results that RS-12 could be an efficient vaccine, especially in the Middle East. This is the first genotype report from Iranian isolates and provides strong data on the molecular epidemiology of mumps in Iran, the Middle East, Central Asia, Russia and other countries of this region.

Mumps outbreak in a highly vaccinated school population: assessment of secondary vaccine failure using IgG avidity measurements

From March to April 2006, an outbreak of mumps occurred in Gyeonggi, Korea. The aim of this study was to describe and discriminate between primary and secondary vaccine failure in a highly vaccinated population for mumps using IgG avidity testing. Fifteen clinical mumps cases occurred among 41 students. Among these 15 patients, 11 vaccinated patients were considered secondary vaccine failures with high IgG titers and a high avidity index (AI, > or =32%); an unvaccinated patient was considered to have primary infection with high IgG titers and low AI, and three vaccinated patients were considered as other infections with low IgG titers and low AI. Among 26 unaffected students, 5 vaccinated patients were retrospectively diagnosed as sub-clinical infection with high IgG titers and high AI; the remaining students had low IgG titers and low AI except for one previously infected student. The results of this study show that secondary vaccine failure played an important role in this mumps outbreak. Therefore, booster immunization for mumps should be considered in immunized adolescents to prevent further outbreaks.

Mapping antigenic diversity and strain specificity of mumps virus: A bioinformatics approach

Mumps is an acute infectious disease caused by mumps virus, a member of the family Paramyxoviridae. With the implementation of vaccination programs, mumps infection is under control. However, due to resurgence of mumps epidemics, there is a renewed interest in understanding the antigenic diversity of mumps virus. Hemagglutinin-neuraminidase (HN) is the major surface antigen and is known to elicit neutralizing antibodies. Mutational analysis of HN of wild-type and vaccine strains revealed that the hypervariable positions are distributed over the entire length with no detectable pattern. In the absence of experimentally derived 3D structure data, the structure of HN protein of mumps virus was predicted using homology modeling. Mutations mapped on the predicted structures were found to cluster on one of the surfaces. A predicted conformational epitope encompasses experimentally characterized epitopes suggesting that it is a major site for neutralization. These analyses provide rationale for strain specificity, antigenic diversity and varying efficacy of mumps vaccines.

Mumps virus strains isolated in Croatia in 1998 and 2005: Genotyping and putative antigenic relatedness to vaccine strains

Two mumps virus strains 9218/Zg98 and Du/CRO05 were isolated in two locations in Croatia in 1998 and 2005, respectively. Genetic characterization of these temporally distinct mumps virus isolates was carried out in order to determine their genotype and putative antigenic relatedness to mumps virus vaccine strains. Sequence analysis of the small hydrophobic (SH) gene revealed that isolate 9218/Zg98 shows less than 95% of similarity to any reference strain, thus representing a potential reference strain for a new genotype. Isolate Du/CRO05 clearly belongs to genotype G with the 97% of homology to the reference strain Glouc1/UK96. When compared to each other, the two Croatian strains have extremely low level of homology of only 89% indicating no relatedness between them. Putative antigenic properties of the HN protein of these two isolates were compared to different vaccine strains. The results reveal a higher level of homology of antigenic determinants to non-A genotype vaccine strains than to A genotype vaccine strain.

Proposal for genetic characterisation of wild-type mumps strains: Preliminary standardisation of the nomenclature

Though mumps virus (MuV) is a monotypic virus, genetic variation between strains has been described. Viruses have been placed into genotypes designated A-L based on the nucleotide sequence of the small hydrophobic (SH) gene, which is the most variable gene in the mumps genome. Molecular characterisation of MuV is an important component of mumps surveillance because it can help identify the transmission pathways of the virus as well as distinguish between wild-type and vaccine strains. Here, we propose a standardized nomenclature and an analysis protocol for the genetic characterisation of mumps strains to facilitate expansion of molecular epidemiological studies. In addition to assigning standard reference strains for the recognized genotypes of MuV, a convention is proposed for naming for strains and criteria to designate a new genotype.

Molecular identification of mumps virus genotypes from clinical samples: standardized method of analysis

A sensitive nested reverse transcription-PCR assay, targeting a short fragment of the gene encoding the small hydrophobic protein (SH gene), was developed to allow rapid characterization of mumps virus in clinical samples. The sensitivity and specificity of the assay were established using representative genotypes A, B, C, D, E, and F. Mumps virus RNA was characterized directly from cerebrospinal fluid (CSF) samples and in extracts of mumps virus isolates from patients with various clinical syndromes. Direct sequencing of products and subsequent phylogenetic analysis enabled genetic classification. A simple web-based system of sequence analysis was established. The study also allowed characterization of mumps virus strains from Argentina as part of a new subgenotype. This PCR assay for characterization of mumps infections coupled to a web-based analytical program provides a rapid method for identification of known and novel strains.

Genetic characterization of L-Zagreb mumps vaccine strain

Eleven mumps vaccine strains, all containing live attenuated virus, have been used throughout the world. Although L-Zagreb mumps vaccine has been licensed since 1972, only its partial nucleotide sequence was previously determined (accession numbers , and ). Therefore, we sequenced the entire genome of L-Zagreb vaccine strain (Institute of Immunology Inc., Zagreb, Croatia). In order to investigate the genetic stability of the vaccine, sequences of both L-Zagreb master seed and currently produced vaccine batch were determined and no difference between them was observed. A phylogenetic analysis based on SH gene sequence has shown that L-Zagreb strain does not belong to any of established mumps genotypes and that it is most similar to old, laboratory preserved European strains (1950s-1970s). L-Zagreb nucleotide and deduced protein sequences were compared with other mumps virus sequences obtained from the GenBank. Emphasis was put on functionally important protein regions and known antigenic epitopes. The extensive comparisons of nucleotide and deduced protein sequences between L-Zagreb vaccine strain and other previously determined mumps virus sequences have shown that while the functional regions of HN, V, and L proteins are well conserved among various mumps strains, there can be a substantial amino acid difference in antigenic epitopes of all proteins and in functional regions of F protein. No molecular pattern was identified that can be used as a distinction marker between virulent and attenuated strains.

Phylogenetic analysis of clinical mumps virus isolates from vaccinated and non-vaccinated patients with mumps during an outbreak, Switzerland 1998-2000

During the past decade mumps outbreaks have occurred in several European countries with universal vaccination programs probably due to poor efficacy of the Rubini vaccine strain. However, the evolution of vaccine escape mutants has also been considered. A phylogenetic analysis was undertaken on 69 clinical mumps isolates obtained from 39 vaccinated and 22 non-vaccinated mumps cases (and six cases with unknown vaccination status) during an outbreak in 1998-2000. Two major strain clusters (SWI-H, SWI-C) with two subgroups each (SWI-H1/2, SWI-C1/2) were identified, which belonged to genotypes C and H. No association between viral clusters and vaccination status or a specific vaccine strain (Jeryl-Lynn or Rubini) was found. Cluster SWI-C1 occurred more frequently in the Western part of Switzerland (P < 0.001). Isolates causing complicated disease tended to cluster more frequently with SWI-H1 (P = 0.11). Wild-type strains homologous or similar to the Rubini vaccine strain (isolated in Switzerland in 1974) were no longer circulating. Therefore, there was no evidence for vaccine escape mutants. Strain redistribution may have occurred during the past decades. Continuous monitoring of circulating mumps virus populations is needed.

Molecular characterization of two genotypes of mumps virus circulated in Korea during 1998-2001

Sequence analyses of the entire small hydrophobic (SH) and hemagglutinin-neuraminidase (HN) genes of mumps viruses circulated in Korea from 1998 to 2001 showed that these isolates were grouped into two genotypes, H and I. While genotype I was predominant throughout the country during this period, genotype H was found in the restricted region, 1999. The nucleotide and deduced amino acid sequences of Korean isolates showed the type-specific changes including the signature motif at positions 28-30 in the SH gene and the neutralizing epitopes in the HN gene. Particularly, Asian strains including Korean isolates and European strains differed from 2.3 to 3.8% at the nucleotide sequence level in the SH gene although they belonged to the same genotype H. Furthermore, none of Korean isolates were genetically related to the vaccine strains used in Korea. The results provide important information to understand the epidemiology of mumps infection and to facilitate the development of more efficient vaccine program in Korea.

Genetic characterization of a mumps virus isolate during passaging in the amniotic cavity of embryonated chicken eggs

The aim of this study was the molecular characterization of a historical mumps isolate (an alleged individual sample). After RNA extraction and cDNA synthesis, selective nested PCR amplification with specific primers, automated DNA sequencing and RFLP analyses were performed. The relative ratios of the detected virus sequences were determined by GeneScan electrophoresis. Phylogenetic tree based on the 316 nucleotide region of the SH gene of the mumps virus was generated by the neighbor-joining method. Results obtained by the described molecular approach show: (a) there are two mumps virus variants, A and B, detected in the fourth passage of wild type virus in the amniotic cavity of embryonated chicken eggs (ECE); (b) variants A and B belong to different genotypes; (c) variants A and B differ in the HN and NP genes which code for amino acid sequences comprising immunogenic epitopes; (d) variant B contains one or more minor variants. We discuss whether the observed differences between the two variants are a consequence of natural heterogeneity or of laboratory contamination in the early passages.

Molecular epidemiology of mumps virus in Japan and proposal of two new genotypes

We isolated 872 strains of mumps virus from naso-pharyngeal secretions in seven different districts of Japan from January 2000 to July 2001. Among them, 57 strains were geno-typed by nucleotide sequencing in part of the hemagglutinin-neuraminidase (HN) and small hydrophobic (SH) protein regions. Four different genotypes (B, G, K, and L) of mumps virus were co-circulating in Japan and the distribution of genotypes varied in geographically different districts. Two new clusters designated as genotypes K and L had more than 7% nucleotide variation in the SH gene. Among the 57 strains, 11 were classified as B, 35 as G, three as K, and eight as L, which was mainly isolated in Tokyo. We also examined 104 stains isolated in a clinic in Mie prefecture from 1993 to 2003. Genotype B was the indigenous strain and genotype K was introduced in 1994. Genotypes B and K co-circulated in the 1990s and were replaced by genotype G in 2000. There was no significant change in neutralizing test antibody titers against genotypes B, G, K, and L using seven post-vaccination sera with Hoshino strain (genotype B) and these four genotypes had a different antigenicity from genotype A. We should continue to watch on mumps virus molecular epidemiology.

Characterization of the F gene of contemporary mumps virus strains isolated in Japan

Mumps virus (MuV) strains isolated in Saitama Prefecture, Japan, from 1997 to 2001, were examined by analyzing the SH and the F gene nucleotide sequences. The results of the SH gene analysis showed that only genotype G was found in 2001 as well as in 2000, and that genotype J, which we proposed as a new genotype in a previous study, was from a different lineage than the genotype J described by Tecle et al. (J. Gen. Virol. 82, 2675-2680). We therefore, propose to rename the genotype as K to avoid confusion. Then, the F gene of genotypes G, H, and K strains were analyzed together with previously reported strains in this study. The results of phylogenetic analysis of the F gene nucleotide sequences showed that these strains formed a cluster as described by the SH gene analysis. Alignment of the F amino acid sequences showed that the F protein was well conserved among strains of different genotypes with a few amino acid differences. These results provide better information for the characterization of contemporary MuV strains in Japan.

Antigenic relationships between six genotypes of the small hydrophobic protein gene of mumps virus

Six different genotypes of mumps virus, A, C, D, G, H and I, genotyped on the basis of the small hydrophobic protein gene sequence, were subjected to antigenic comparison. Monoclonal antibodies directed against the haemagglutinin-neuraminidase protein of the SBL-1 strain of genotype A were used in immunofluorescence tests with different mumps virus strains. In addition, the six virus genotypes were compared by cross-neutralization tests with human post-vaccination sera after vaccination with the Jeryl Lynn (JL) strain of mumps virus and with rabbit hyperimmune sera directed against the A or D genotypes of mumps virus. Genotypes C, D, G, H and I could not be antigenically separated. In contrast, three different virus strains of genotype A, SBL-1, JL and Kilham, were distinct and were found to represent three different serotypes within the A genotype of mumps virus. Vaccination of Swedish children with the JL strain of mumps virus resulted in clearly lower neutralization titres against the SBL-1 strain, which is endemic in Sweden, compared to the homologous vaccine titres.

Characterization of mumps virus isolated in saitama prefecture, Japan, by sequence analysis of the SH gene

Mumps virus (MuV) strains isolated from cerebrospinal fluid and throat swabs from patients in Saitama Prefecture and Tokyo, Japan, from 1997 to 2000 were examined by analyzing the SH gene nucleotide sequence (316-nt). Eighteen of the 20 strains studied were divided into three genotypes, recognized as B, G, and H in previous reports. Two genotypes (G and H) are believed to be new in Japan. Two of the 20 strains belonged to none of the previously reported genotypes (A-I), but were closely related to two known strains, MP94-H and Loug1/UK97. We propose that the two strains identified in this study together with the previously reported strains, MP94-H and Loug1/UK97, form a new genotype, designated J, based on the divergence of the SH gene nucleotide sequences between these four strains and other strains reported (genotypes A-I). Our results also suggest that more than two genotypes circulated in Saitama Prefecture from 1997 to 1999, but only one, genotype G, was in evidence in 2000. Genotype B was earlier reported as the predominant strain in Japan, but it became undetectable by the year 2000. These results provide important epidemiological data on mumps in Japan.

Characterization of two decades of temporal co-circulation of four mumps virus genotypes in Denmark: identification of a new genotype

Twenty-nine Danish virus isolates and 14 serum samples from patients with mumps were genotyped by nucleotide sequencing of the small hydrophobic (SH) protein gene and the deduced 57 amino acid sequences were aligned with sequences of mumps virus strains published previously. Four neurovirulent genotypes of the SH protein gene, genotypes C, D, H and a new genotype, designated J, were found. There was a dynamic fluctuation of the different genotypes over the two decade period of time. Genotype J was found from 1981 to 1988; genotypes C and H exhibited a similar distribution in time. Genotype D was found between 1979 and 1982, it then disappeared and reappeared again in 1996. From 1996 onwards, genotype D was found to be the predominant genotype, which is in contrast to the situation seen in the neighbouring country of Sweden, where, since 1985, only genotype A has been found.

The genomic sequence of a contemporary wild-type mumps virus strain

Vaccination has the potential to eradicate mumps, and 82 countries now include a live attenuated mumps vaccine as part of their childhood vaccination programme. Although, monotypic, genetic variants of mumps virus (MuV) have been described based on comparison of the SH gene sequences, and at least seven genotypes have been identified. We now report the entire sequence of a recently isolated wild type MuV strain, Glouc1/UK96 (Glouc1) by direct sequencing of the cDNA obtained from cell culture fluid. The genome of this recent isolate was 15384 nucleotides in length. There were 579 nucleotide differences (3.8%) and 71 amino acid differences (1.5%) between Glouc1, a genotype G strain and Ur-AM9, a genotype B strain. Other MuV strains with available sequences were also compared with this pathological strain. The sequence of the contemporary strain reported here provides a picture of the variability of MuV over its entire genome (GenBank accession no. AF280799).

Phylogenetic analysis of the small hydrophobic (SH) gene of mumps virus in Korea: identification of a new genotype

Viral RNAs extracted from fifteen mumps virus isolated from throat swab, saliva, blood, urine or CSF during mumps epidemics between 1997-1998 in Korea were amplified by reverse transcriptase-polymerase chain reaction (RT-PCR) and compared by nucleotide sequencing of the small hydrophobic (SH) gene. The deduced amino acid sequences of the SH gene were aligned with the published sequences of mumps virus isolated in different geographic areas. A comparison of the SH gene of mumps viruses in Korea indicated 96.2-100% and 91.2-100% similarity at the nucleotide and amino acid levels, respectively. Phylogenetic analysis, using the neighbor-joining method, showed that Korean mumps virus strains formed a genetically distinct monophyletic group from previously reported genotypes based on the 315-bp length nucleotide and 57 deduced amino acid sequences of the SH gene, and possibly be designated as a new genotype (I).

Assay of humoral immunity to mumps virus

One hundred randomly chosen sera from blood donors from North London were assayed for antibodies to mumps virus by plaque reduction and microtitre neutralisation assay, haemagglutination inhibition and in-house ELISA. The assay reproducibility was determined, and there was reasonable agreement between antibody levels measured by the two neutralising methods. Neutralising antibody levels measured by either method were low but the strain used in the assay had a large effect on the antibody titres observed. Titres measured by neutralisation assay, HI assay and ELISA did not correlate well. Assessment of immunity to mumps virus remains problematical.