Hemagglutinin-neuraminidase sequence and phylogenetic analyses of mumps virus isolates from a vaccinated population in Singapore

During 1999-2000, a sustained mumps outbreak in the highly vaccinated population in Singapore was attributed to vaccine failure associated with the Rubini vaccine strain. To explain this phenomenon, the complete nucleotide and amino acid sequences of the hemagglutinin-neuraminidase (HN) gene of eight mumps virus isolates from patients with parotitis in Singapore were determined and compared with those of known vaccine strains. Phylogenetic trees constructed on the basis of HN nucleotide and amino acid sequences showed that the Singapore mumps virus isolates were more closely related to the Urabe strain and belonged to a different cluster from the Rubini and Jeryl-Lynn strains. The Rubini vaccine showed only approximately 93% nucleotide and approximately 96% amino acid sequence similarity to Urabe and Singapore isolates. Compared with the vaccine strains, six of the eight isolates lacked the extracellular glycosylation site at residues 400-402. Other significant amino acid disparities (e.g., at residue 354) may also affect the antigenic properties of the HN protein. These findings suggest that the evolution and adaptation of the currently circulating mumps virus strains in the community has led to the emergence of genetically distinct viral strains. The low vaccine efficacy of the Rubini strain represents a major reason for the recent mumps resurgence and failure of mumps immunization in Singapore.     

Rescue of wild-type mumps virus from a strain associated with recent outbreaks helps to define the role of the SH ORF in the pathogenesis of mumps virus

Mumps virus (MuV) causes acute infections in humans. In recent years, MuV has caused epidemics among highly vaccinated populations. The largest outbreak in the U.S. in the past 20 years occurred in 2005-2006 with over 5000 reported cases in which the majority of the cases was in vaccinated young adults. We sequenced the complete genome of a representative strain from the epidemic (MuV-IA). MuV-IA is a member of genotype G, the same genotype of MuV that was associated with the outbreak in the UK in 2004-2005. We constructed a reverse genetics system for MuV-IA (rMuV-IA), and rescued a virus lacking the open reading frame (ORF) of the SH gene (rMuV?SH). rMuV?SH infection in L929 cells induced increased NF-κB activation, TNF-α production and apoptosis compared to rMuV-IA. rMuV?SH was attenuated in an animal model. These results indicated that the SH ORF of MuV plays a significant role in interfering with TNF-α signaling and viral pathogenesis during virus infection.     

Hepatitis C virus genotyping in Greece: unexpected high prevalence of genotype 5a in a Greek island

Hepatitis C virus (HCV) genotype 5 (G5) is a rare genotype reported mainly in South Africa. However, increasing data suggest the sporadic presence of this genotype in different European countries. To assess the epidemiology of HCV‐G5 in Greece, genotyping was performed in 973 consecutive patients infected with HCV, referred to 7 hepatology centers throughout Greece, from January 2005 to December 2009. Genotype 5a (19 patients, 1.9%) was the fifth most prevalent genotype after genotype 1 (408 patients, 41.9%), genotype 3 (318 patients, 32.7%), genotype 4 (158 patients, 16.2%), and genotype 2 (70 patients, 7.2%). The majority of patients infected with G5 (16/19,84.2%) were referred to the General Hospital of Rhodes, an island in south‐east Greece. The HCV genotype distribution in that particular island, indicates a particularly high G5 prevalence of 12.8%, after genotype 1 (40%), genotype 3 (28%), and genotype 4 (15%). Among the patients from Rhodes infected with G5 (n = 16), 13 (81.2%) were females. The mean age was 62.3 ± 6.5 years, significantly older than the patients infected with other HCV genotypes (mean age 40.6 ± 7.2, P < 0.0001). Nine out of the 16 cases (56.2%) presented features of high pre‐treatment viral loads. Advanced liver fibrosis (Metavir F3–F4) was found in four out of five performed liver biopsies. Ten patients received treatment with pegylated interferon plus ribavirin and a sustained viral response were achieved in six cases. The source of infection is unknown but parenteral iatrogenic routes of transmission seem to have contributed significantly to the spread of genotype 5a in this region. J. Med. Virol. 84:223–228, 2012. © 2011 Wiley Periodicals, Inc.     

Mutations in the nonstructural region 5B of hepatitis C virus genotype 1b: their relation to viral load, response to interferon, and the nonstructural region 5A

The nonstructural 5B (NS5B) protein of hepatitis C virus possesses RNA-dependent RNA polymerase activity and plays an essential role in viral replication. The mutations in NS5B were determined and the correlation with viral load and response to interferon (IFN) were assessed. The entire NS5B region in 33 patients and its thumb domain in 62 patients was sequenced. The number of amino acid substitutions in the NS5B protein, that in thumb domain and the substitution at aa 389 was correlated with viral load and the response to IFN. Multivariate analysis selected only mutation in IFN sensitivity determining region (ISDR) as a factor associated with the viral load and response to IFN. The number of substitutions in the thumb domain and the substitution at aa 389 correlated with the number of substitutions in the ISDR. These results suggest that mutations in NS5B, especially in the thumb domain and at aa 389, have an important effect on viral load and the response to IFN, although they were dependent on mutations in ISDR. Further studies on the relationship between NS5B and NS5A (ISDR) are necessary to elucidate the mechanism of the correlation with viral load and the response to IFN.     

Prevalence of hepatitis C virus genotype 1a in Japan and correlation of mutations in the NS5A region and single-nucleotide polymorphism of interleukin-28B with the response to combination therapy with pegylated-interferon-alpha 2b and ribavirin

Hepatitis C virus (HCV) genotype 1a is rare in Japanese patients and the clinical characteristics of this genotype remain unclear. The interferon (IFN) sensitivity‐determining region (ISDR) and single‐nucleotide polymorphisms (SNPs) of interleukin‐28B (IL28B) among patients with HCV genotype 1b are associated with IFN response, but associations among patients with genotype 1a are largely unknown. This study investigated the clinical characteristics of genotype 1a and examined whether genomic heterogeneity of the ISDR and SNPs of IL28B among patients with HCV genotype 1a affects response to combination therapy with pegylated‐IFN‐α2b and ribavirin. Subjects comprised 977 patients infected with HCV genotype 1, including 574 men and 412 women (mean age, 55.2 ± 10.6 years). HCV was genotyped by direct sequencing of the 5′‐untranslated region and/or core regions and confirmed by direct sequencing of the NS5A region. HCV genotypes 1a (n = 32) and 1b (n = 945) were detected. Twenty‐three (71.9%) of the 32 patients with genotype 1a were patients with hemophilia who had received imported clotting factors. Prevalence of genotype 1a after excluding patients with hemophilia was thus 0.9%. Of the 23 patients with genotype 1a who completed IFN therapy, 11 (47.8%) were defined as achieving sustained virological response. Factors related to sustained virological response by univariate analysis were IL28B and ISDR. In conclusion, HCV genotype 1a is rare in Japan. The presence of IL28B genotype TT, and more than two mutations, in the ISDR are associated with a good response to IFN therapy in patients with HCV genotype 1a. J. Med. Virol. 84:438–444, 2012. © 2011 Wiley Periodicals, Inc.