Specific humoral immunity after single immunization with mumps vaccine: data of a 3-year follow-up

The level and spectrum of humoral specific immunity were studied in 60 volunteers immunized with Russian mumps vaccine. Specific IgG levels were measured by enzyme immunoassay (EIA) and neutralization test using the Leningrad-3 (L-3) mumps virus (MV) vaccine strain and 5 heterologous MV strains of various genotypes (A, B, C, D, and H). The maximum functional activity of antibodies was recorded at an average of 18 months postvaccination. Within 3 years after vaccination, starting at 6 months, specific IgG neutralized all 6 MV strains having varying activity in relation to the genotype. Neutralizing titers (NT) against the L-3 strain were 1.3-1.7-fold higher than those against heterologous MV strains throughout the follow-up. Despite a tendency towards lower specific IgG levels, within 3 years postvaccination, EIA IgG titers remained to be 2.5 -log, L-3 strain HT were -log, or more, and the titers against 5 heterologous MV strains were 2 -log2 or more in all the volunteers.     

Measles in Minsk, Belarus, 2001-2003: clinical, virological and serological parameters.

BACKGROUND: A number of cases of measles have been reported in the Republic of Belarus despite vaccine coverage of 98%. The absence of information on measles virus genotypes circulating in the Republic of Belarus has made it difficult to asses the situation. OBJECTIVES: The purpose of this study was to isolate and sequence measles virus strains from clinical cases in Minsk, Belarus, and to estimate the role of vaccine failure in those cases. STUDY DESIGN: Between 2001 and 2003 years, 14 measles cases admitted to the Hospital of Infectious Diseases of Minsk were enrolled in our study. Clinical, routine laboratory, as well as serological and virological examinations were carried out. Detection of measles antibodies and IgG avidity testing was performed using commercial test kits. All measles cases were confirmed by RT-PCR and phylogenetically characterized. RESULTS: Only 42.9% of the cases met the WHO laboratory criteria for measles, however, all cases were confirmed by RT-PCR. Most of the measles cases were attributed to secondary vaccine failure (SVF). Phylogenetic analysis revealed the presence of genotype A virus strains in 2001 and 2002 with D6 and D7 genotypes in 2003. CONCLUSIONS: For the first time, MVs were genetically characterized in Belarus. Our results suggest that in a highly vaccinated population, most of measles cases represent vaccine failures and are vaccine-modified. Our results also indicate that confirmation of a clinical diagnosis of vaccine-modified measles requires a combination of serological and virological tests.     

Molecular identification of two genotypes of mumps virus causing two regional outbreaks in Asturias, Spain

BACKGROUND: In spite of universal vaccination, several sporadic cases of mumps infection, which could produce outbreaks, are detected every year in different countries. OBJECTIVE: Mumps virus strains causing two regional outbreaks in Asturias (Spain) were phylogenetically characterized. STUDY DESIGN: Mumps virus strains, which were detected in samples from patients belonging to two regional outbreaks in Asturias, were characterized by sequencing of the SH gene and further alignment to homologous sequences of representative strains of the different mumps genotypes. RESULTS: Two different strains (Ast/SP02 and Ast/SP07) were isolated. Sequence analysis revealed that while Ast/SP02 belonged to genotype H, Ast/SP07 was phylogenetically close to UK02-19, a reference strain for a new genotype. Both strains belonged to different genotypes from those used in the vaccination (Jeryl-Lynn strain is genotype A). CONCLUSION: Mumps virus strains different from those used in vaccination program can cause mumps outbreaks even in vaccinated patients.     

Single genotype of measles virus is dominant whereas several genotypes of mumps virus are co-circulating

We have reported that in Japan measles virus strains have been classified into three distinct different genotypes (C1, D3 and D5) under the new international genotype classification since 1984. Similarly, mumps virus strains have been divided into two genotypes with three subtypes (B1, B2, B3, and D) under the proposed international classification since 1976. To differentiate these genotypes we developed a restriction fragment length polymorphism assay in the hemagglutinin (H) region for measles virus and in the hemagglutinin-neuraminidase (HN) region for mumps virus to facilitate the expanded molecular epidemiology. In the Sapporo 1995/1996 measles outbreak, all 26 strains were classified as D5. Among 32 samples from patients with measles from 1994 to 1997 in Tokyo, 28 were identified as D5 and four were D3; these D3 strains were ascertained as a same hospital acquired infection. Among 45 strains obtained in the Tokyo 1999 outbreak, 38 were D3 and the remaining seven were D5. The dominant genotype of measles in Tokyo has replaced from D5 to D3 similar to the Chicago1/89 strain. We obtained 220 samples from patients with mumps from 1993 to 1997 and they were classified into one strain of B1, 14 strains of B2, 151 strains of B3, and 54 strains of D. Therefore, we suggest that two or three subtypes of mumps virus are co-circulating with a different geographic pattern in genotype distribution, whereas a single measles virus genotype is dominantly observed, showing different epidemiological patterns.     

Comparative evaluation of Leningrad-3 mumps vaccine virus neurovirulence in a neonatal rat model

The neurovirulence and replication potential of several mumps virus strains, including Leningrad-3 mumps vaccine virus (FSUE SIC "Microgen", Russia) and wild type strains isolated in the Novosibirsk Region (Russia), were assessed in rat tests. The mean neurovirulence scores of the Leningrad-3 virus (< 4.0) were significantly lower than those of wild type strains (ranging from 6.1 to 15.2) and were in accordance with the scores determined for other attenuated mumps vaccine strains (usually ranging from 0 to 5). In general, the relative ability of the viruses to replicate in the rat brain tracked with their neurovirulence scores. These results indicate a low neurovirulence potential of the Leningrad-3 mumps vaccine virus for humans.     

Serological response to hepatitis E virus genotype 3 infection: IgG quantitation, avidity, and IgM response

Sequential sera were collected from 18 acute cases of UK-acquired hepatitis E. The virus strains in all cases were of genotype 3. The IgM and IgG response to acute infection were documented over time using EIA kits based on a peptide antigen, pE2, which is derived from a genotype 1 strain of hepatitis E virus (HEV). Ninety-five percentage of acute sera were IgM positive; after 6 months or more only 12% remained positive. The kit was adapted to quantify the IgG response (in WHO U/ml) and to determine antibody avidity. Following acute infection, anti-HEV IgG concentrations rose between 6.9- and 90-fold. IgG avidity was low (<25%) in most acute sera. After 6 months IgG avidity was greater than 50% in all cases. One patient with a poor IgM response and high avidity antibody in acute sera may have had a second HEV infection. Taken together, these results confirm that the pE2-based EIA kits are suitable for diagnosing acute HEV genotype 3 infection. With simple modifications the IgG kit can measure anti-HEV concentration and avidity, which can be used to confirm acute infection.     

Virus strain specific serum neutralizing antibodies in children and adolescents immunized with a Russian mumps vaccine

Postvaccination immunity was studied in the children and teenagers without a history of clinical mumps infection, who had been immunized with the Leningrad-3 mumps vaccine. The level of specific lgG in ELISA and that and spectrum of their neutralizing activity against a vaccine strain and three heterologous mumps virus (MV) strains (genotypes A, C, and H) were measured. The investigation included 151 sera from the vaccinees aged 3 to 17 years, possessing the detectable specific IgG titers in ELISA and the detectable neutralizing titers against the vaccine strain. 97.4% of the vaccinees had neutralizing activity against 1-3 heterologous MV strains. A preponderance of neutralizing titers against heterologous MV strains by 1-log2 in some sera (6.5-32.5 depending on age) was most likely to suggest that the vaccinees' had been in contact with these virus strains in the past. In our investigation, a combination of positive IgG titers and neutralizing titers against the vaccine strain 2-log2 or higher provided the protection of the vaccinated children and teenagers against the symptomatic infection. There was a pronounced buster effect of the second immunization and a drop in the neutralizing activity of the sera from the vaccinated children and adolescents over time after the first and second immunization.     

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

Summary. 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.     

Detection of measles,mumps, and rubella antibodies in saliva using antibody capture radioimmunoassay

Antibody capture radioimmunoassays were developed for detecting virus specific IgM (MAC-RIA) and IgG (GACRIA) to measles, mumps, and rubella and used to investigate saliva as an alternative specimen to serum for diagnosis. Saliva was collected from 63 patients with measles, 19 with mumps, and 150 with rubella, which were all clinically diagnosed and serologically confirmed. Virus specific IgM was detected in 92% of measles, 75% of mumps, and 100% of rubella saliva samples collected during the first week of illness. Between 1 and 5 weeks after onset virus specific IgM was detected in 100% of saliva specimens. After the 5th week the proportion of reactive specimens declined. The specificity of the MACRIA tests was established by testing saliva samples collected from blood donors for measles (88), mumps (88), and rubella IgM (91). All of the saliva specimens tested for measles and rubella specific IgM were unreactive, 1/88 specimens tested for mumps specific IgM contained significant reactivity. Saliva specimens collected from acute cases of MMR were tested in all 3 MACRIAs. A small proportion of saliva samples contained detectable IgM of more than one virus infection. Rubella and measles specific IgG was detected in the saliva of all cases from the 4th or 5th day of illness, respectively. Detection of mumps specific IgG was less successful. We have demonstrated that virus specific IgM can be reliably detected in saliva samples collected from acute cases of measles, mumps, and rubella and identified 1–5 weeks after onset of illness as the optimum time for collection of samples. © 1993 Wiley-Liss, Inc.     

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.     

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.     

Genotyping of mumps virus circulating in Turkey in the 2006–2007 winter season

In the winter of 2006–2007, several parotitis cases were reported in different provinces of Turkey. Serological and virological studies were undertaken to investigate these cases with the aim of determining the genotype of the mumps virus (MuV) circulating in Turkey. Samples from 23 cases—Ankara (n:5), Kırklareli (n:4), Mugla (n:10), Isparta (n:3), Trabzon (n:1)—with a diagnosis of clinical parotitis were investigated. Serum samples were tested against mumps IgM and IgG, nested PCR amplification of a 639-bp fragment encompassing the entire SH gene was performed using buccal swabs, and PCR products were sequenced. Of 18 serum samples, 16 (88.9%) were positive for mumps IgM. Seven (30.4%) of 23 buccal swab samples were positive by PCR. In five PCR-positive cases, the sample was also positive for mumps IgM, and serum samples were not available from two of the PCR-positive cases. There was 98% identity between the different sequences, and all were identified as genotype H. The sequences were most similar to sequences identified in Spain, Japan, Switzerland and the UK, and less closely related to the H strains identified in Belarus, Korea and Russia. This is the first report of the mumps virus genotypes circulating in Turkey. Turkey is, geographically, a bridge between Europe and Asia, and therefore, a better understanding of the molecular epidemiology of MuV in Turkey may led to improved tracking of the circulation of strains between the two continents. Moreover, there is a need to further investigate the existence of other genotypes in Turkey.     

Mumps outbreaks in a highly vaccinated population: Investigation of a neutralization titre against the current circulating wildtype genotype G5 mumps virus

BackgroundMumps outbreaks continue to occur globally, despite high levels of uptake of the mumps vaccine.ObjectivesIn order to address immunity to the current circulating wildtype virus, we sought to determine a mumps G5 specific IgG quantitative value which correlates with genotype G5 specific neutralization ability in vitro.Study designSera from 199 individuals including controls and acute mumps cases were assessed for mumps specific IgG titres using five different enzyme immunoassays coated with antigen from different mumps virus strains. A subset of 66 sera was also assessed for in vitro neutralizing antibody against a contemporary circulating genotype G5 mumps virus.ResultsFor all the different antigenic targets, mumps specific IgG titres were higher in patients following acute mumps infection compared to controls. In acute mumps infected patients, females showed significantly higher serum titres of anti-G5 IgG compared to males (p < 0.05). Furthermore, control males did not show any change in G5 specific IgG with increasing age whereas females show a progressive rise in titre. Linear regression analysis revealed a significant association between the mumps G5 specific IgG levels in the EIA and the in vitro neutralization titres (r² = 0.59).ConclusionsSpecific IgG to the current circulating genotype G5 mumps strain showed significantly lower titres in males which supports our previous observation that there is a male gender bias in cases of acute mumps infection. Furthermore, in this preliminary study, the data indicate that genotype G5 specific IgG levels of >40 RU/ml are required for neutralization capability to be observed in vitro.     

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.     

Analysis of Mumps Vaccine Failure by Means of Avidity Testing for Mumps Virus-Specific Immunoglobulin G

To characterize patients with mumps vaccine failure, avidity testing was performed with the Enzygnost Anti-Parotitis Virus/IgG kit using a single-dilution–6 M urea denaturation method. Five groups of patients were tested. Group 1 consisted of 29 patients with primary mumps infections; group 2 was 20 children and adults with a definite history of natural infection; group 3 was 7 patients with a recent mumps vaccination, 1 of whom developed parotid gland swelling and aseptic meningitis; group 4 was 14 patients with mumps vaccine failure; and group 5 was 6 patients with recurrent episodes of parotitis in addition to a history of vaccination. On the basis of the results of groups 1 and 2, an avidity of 31% was determined to be low, and 32% was determined to be high. Avidity maturation from low to high appears to occur around 180 days after the acute illness. The results of group 3 showed that the vaccine-induced immunoglobulin G (IgG) had very low avidity. Among the 14 patients in group 4, 12 patients, including 7 with a positive IgM response, were diagnosed as having secondary vaccine failures. The results of group 5 suggested the possibility that the avidity of the mumps vaccine-induced IgG remains low or borderline. These results showed that secondary mumps vaccine failure occurs not infrequently, even among school age children under condition in which the vaccine coverage is low (i.e., 33% in our study population), and therefore, vaccinees are prone to be exposed to wild-type viruses. Avidity testing should provide information useful for the analysis of mumps virus infections.     

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.     

Regional outbreak of mumps due to genotype H in Korea in 1999

Serological and virological studies were carried out of a mumps outbreak which occurred in one region, Yoeju County, Southeast of Seoul in Korea from September to December, 1999. Sera from 736 children at 8-13 years of age of patients with mumps and healthy children were tested for mumps-specific antibodies by enzyme immunoassay. The overall IgM positive rate was 7.6% (56/736), compared with 69.8% (514/736) for IgG. Of the 49 children with both IgG and IgM, 32 were also confirmed by both clinical and serological diagnosis. IgM antibodies were detected even in the samples collected up to 3 months after the onset of symptoms. Although 436 children had been vaccinated before the outbreak, 27 (6.2%) were found to be IgM positive, particularly 6 (4.4%) of 136 were positive serologically despite a second-dose vaccinees. Sequence analysis of the small hydrophobic (SH) gene of 4 mumps viruses isolated from 42 saliva specimens revealed that these were related to the genotype H, but distinguishable from European strains. This is the first study on the outbreak due to mumps virus genotype H and provides information to assess the understanding of recent outbreaks of mumps in Korea.     

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.     

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.