Particularly vulnerable are health care workers who do not use personal protective equipment and persons who do not wash hands after traditional burial practices.
Active Nipah virus encephalitis surveillance identified an encephalitis cluster and sporadic cases in Faridpur, Bangladesh, in January 2010. We identified 16 case-patients; 14 of these patients died. For 1 case-patient, the only known exposure was hugging a deceased patient with a probable case, while another case-patient’s exposure involved preparing the same corpse for burial by removing oral secretions and anogenital excreta with a cloth and bare hands. Among 7 persons with confirmed sporadic cases, 6 died, including a physician who had physically examined encephalitis patients without gloves or a mask. Nipah virus–infected patients were more likely than community-based controls to report drinking raw date palm sap and to have had physical contact with an encephalitis patient (29% vs. 4%, matched odds ratio undefined). Efforts to prevent transmission should focus on reducing caregivers’ exposure to infected patients’ bodily secretions during care and traditional burial practices.
Nipah; encephalitis; outbreak; Nipah virus; NiV; nosocomial; healthcare-associated infection; corpse; Bangladesh; viruses; burial practices; PPE; personal protective equipment; health care workers; transmission
Nipah virus (NiV) is a highly pathogenic zoonotic paramyxovirus that causes fatal encephalitis in up to 75% of infected humans. Like other paramyxoviruses, NiV employs co-transcriptional mRNA editing during transcription of the phosphoprotein (P) gene to generate additional mRNAs encoding the V and W proteins. The C protein is translated from the P mRNA, but in an alternative reading frame. There is evidence from both in vitro and in vivo studies to show that the P gene products play a role in NiV pathogenesis. We have developed a reverse genetic system to dissect the individual roles of the NiV P gene products in limiting the antiviral response in primary human microvascular lung endothelial cells, which represent important targets in human NiV infection. By characterizing growth curves and early antiviral responses against a number of recombinant NiVs with genetic modifications altering expression of the proteins encoded by the P gene, we observed that multiple elements encoded by the P gene have both distinct and overlapping roles in modulating virus replication as well as in limiting expression of antiviral mediators such as IFN-β, CXCL10, and CCL5. Our findings corroborate observations from in vivo hamster infection studies, and provide molecular insights into the attenuation and the histopathology observed in hamsters infected with C, V, and W-deficient NiVs. The results of this study also provide an opportunity to verify the results of earlier artificial plasmid expression studies in the context of authentic viral infection.
Mumps virus (MuV) causes an acute infection in humans characterized by a wide array of symptoms ranging from relatively mild manifestations, such as parotitis, to more-severe complications, such as meningitis and encephalitis. Widespread mumps vaccination has reduced mumps incidence dramatically; however, outbreaks still occur in vaccinated populations. The V protein of MuV, when expressed in cell culture, blocks interferon (IFN) expression and signaling and interleukin-6 (IL-6) signaling. In this work, we generated a recombinant MuV incapable of expressing the V protein (rMuVΔV). The rescued MuV was derived from a clinical wild-type isolate from a recent outbreak in the United States (MuVIowa/US/06, G genotype). Analysis of the virus confirmed the roles of V protein in blocking IFN expression and signaling and IL-6 signaling. We also found that the rMuVIowa/US/06ΔV virus induced high levels of IL-6 expression in vitro, suggesting that V plays a role in reducing IL-6 expression. In vivo, the rMuVIowa/US/06ΔV virus was highly attenuated, indicating that the V protein plays an essential role in viral virulence.
The incidence of measles in China from 1991 to 2008 was reviewed, and the nucleotide sequences from 1507 measles viruses (MeV) isolated during 1993 to 2008 were phylogenetically analyzed. The results showed that measles epidemics peaked approximately every 3 to 5 years with the range of measles cases detected between 56,850 and 140,048 per year. The Chinese MeV strains represented three genotypes; 1501 H1, 1 H2 and 5 A. Genotype H1 was the predominant genotype throughout China continuously circulating for at least 16 years. Genotype H1 sequences could be divided into two distinct clusters, H1a and H1b. A 4.2% average nucleotide divergence was found between the H1a and H1b clusters, and the nucleotide sequence and predicted amino acid homologies of H1a viruses were 92.3%–100% and 84.7%–100%, H1b were 97.1%–100% and 95.3%–100%, respectively. Viruses from both clusters were distributed throughout China with no apparent geographic restriction and multiple co-circulating lineages were present in many provinces. Cluster H1a and H1b viruses were co-circulating during 1993 to 2005, while no H1b viruses were detected after 2005 and the transmission of that cluster has presumably been interrupted. Analysis of the nucleotide and predicted amino acid changes in the N proteins of H1a and H1b viruses showed no evidence of selective pressure. This study investigated the genotype and cluster distribution of MeV in China over a 16-year period to establish a genetic baseline before MeV elimination in Western Pacific Region (WPR). Continuous and extensive MeV surveillance and the ability to quickly identify imported cases of measles will become more critical as measles elimination goals are achieved in China in the near future. This is the first report that a single endemic genotype of measles virus has been found to be continuously circulating in one country for at least 16 years.
New genotyping scheme facilitates classification of virus sequences.
Nipah virus (NiV) is a highly pathogenic paramyxovirus that causes fatal encephalitis in humans. The initial outbreak of NiV infection occurred in Malaysia and Singapore in 1998–1999; relatively small, sporadic outbreaks among humans have occurred in Bangladesh since 2001. We characterized the complete genomic sequences of identical NiV isolates from 2 patients in 2008 and partial genomic sequences of throat swab samples from 3 patients in 2010, all from Bangladesh. All sequences from patients in Bangladesh comprised a distinct genetic group. However, the detection of 3 genetically distinct sequences from patients in the districts of Faridpur and Gopalganj indicated multiple co-circulating lineages in a localized region over a short time (January–March 2010). Sequence comparisons between the open reading frames of all available NiV genes led us to propose a standardized protocol for genotyping NiV; this protcol provides a simple and accurate way to classify current and future NiV sequences.
Nipah; Nipah virus; outbreak; encephalitis; phylogeny; viruses; Bangladesh
Although high measles, mumps, and rubella (MMR) vaccination coverage has been successful in dramatically reducing mumps disease in the United States, mumps (re)infections occasionally occur in individuals who have been either previously vaccinated or naturally infected. Standard diagnostics that detect virus or virus-specific antibody are dependable for confirming primary mumps infection in immunologically naïve persons, but these methods perform inconsistently for individuals with prior immune exposure. We hypothesized that detection of activated mumps-specific antibody-secreting B cells (ASCs) by enzyme-linked immunospot (ELISPOT) assay could be used as a more reliable diagnostic. To test this, a time course of virus-specific ASC responses was measured by ELISPOT assay following MMR vaccination of 16 previously vaccinated or naturally exposed adult volunteers. Mumps-specific ASCs were detectable in 68% of these individuals at some point during the first 3 weeks following revaccination. In addition, mumps-specific ASCs were detected in 7/7 previously vaccinated individuals who recently had been infected as part of a confirmed mumps outbreak. These data suggest that ELISPOT detection of mumps-specific ASCs has the potential for use as an alternative method of diagnosis when suspect cases cannot be confirmed by detection of IgM or virus. In addition, it was determined that mumps-specific memory B cells are detected at a much lower frequency than measles- or rubella-specific cells, suggesting that mumps infection may not generate robust B-cell memory.
Nipah virus (NiV) and Hendra virus (HeV) are zoonotic paramyxoviruses capable of causing severe disease in humans and animals. These viruses require biosafety level 4 (BSL-4) containment. Like other paramyxoviruses, the plaque reduction neutralization test (PRNT) can be used to detect antibodies to the surface glycoproteins, fusion (F) and attachment (G), and PRNT titers give an indication of protective immunity. Unfortunately, for NiV and HeV, the PRNT must be performed in BSL-4 containment and takes 5–7 days to complete. Thus, we have developed a neutralization assay using VSV pseudotype particles expressing the F and G proteins of NiV (pVSV-NiV-F/G) as target antigens. This rapid assay, which can be performed at BSL-2, was evaluated using serum samples from outbreak investigations and more than 300 serum samples from an experimental NiV vaccination study in swine. The results of the neutralization assays with pVSV-NiV-F/G as antigen showed a good correlation with those of standard PRNT. Therefore, this new method has the potential to be a rapid and cost-effective diagnostic method, especially in locations that lack high containment facilities, and will provide a valuable tool for basic research and vaccine development.
Hendra and Nipah viruses are recently emerged zoonotic paramyxoviruses for which there is no vaccine or protective therapy available. While a number of experimental therapeutics and vaccines have recently been reported, all of these will require lengthy approval processes, limiting their usefulness in the short term. To address the urgent need for henipavirus therapeutics, a number of currently licensed pharmaceuticals have been evaluated for off label efficacy against henipavirus replication in vitro. Initially it was observed that compounds which released intracellular calcium stores induced a potent inhibition of henipaviruses replication, prompting the evaluation of known drugs with a similar effect on calcium mobilisation. Of the eight compounds randomly selected based on existing literature, seven inhibited virus replication in the micromolar range while the remaining compound also inhibited virus replication but only at millimolar concentrations. Pretreatment experiments with various calcium chelators, channel antagonists or endoplasmic reticulum release inhibitors supported a calcium mediated mechanism of action for five of these compounds. The mechanism of antiviral action for the remaining three compounds is currently unknown. Additionally, a number of other modulators of calcium flux, including calcium channel and calmodulin antagonists also exhibited potent antiviral activity in vitro providing a broad range of potential therapeutic options for the treatment of henipavirus infections. Importantly, as many of these compounds are currently licensed drugs, regulatory approval should be a much more streamlined process, with the caveat that appropriate in vivo efficacy can be demonstrated in animal models.
Nipah virus; Hendra virus; Henipaviruses; Antiviral; Calcium
Outbreaks of Hendra (HeV) and Nipah (NiV) viruses have been reported starting in 1994 and 1998, respectively. Both viruses are capable of causing fatal disease in humans and effecting great economical loss in the livestock industry.
Through screening of hybridomas derived from mice immunized with γ-irradiated Nipah virus, we identified two secreted antibodies; one reactive with the nucleocapsid (N) protein and the other, the phosphoprotein (P) of henipaviruses. Epitope mapping and protein sequence alignments between NiV and HeV suggest the last 14 amino acids of the carboxyl terminus of the N protein is the target of the anti-N antibody. The anti-P antibody recognizes an epitope in the amino-terminal half of P protein. These monoclonal antibodies were used to develop two antigen capture ELISAs, one for virus detection and the other for differentiation between NiV and HeV. The lower limit of detection of the capture assay with both monoclonal antibodies was 400 pfu. The anti-N antibody was used to successfully detect NiV in a lung tissue suspension from an infected pig.
The antigen capture ELISA developed is potentially affordable tool to provide rapid detection and differentiation between the henipaviruses.
Better understanding of transmission patterns will enhance control and elimination programs.
To determine the origin of the virus associated with a measles outbreak in Menglian County, Yunnan Province, People’s Republic of China, in 2009, we conducted genetic analyses. Phylogenetic analyses based on nucleoprotein (N) and hemagglutinin (H) gene sequences showed that these Menglian viruses were not closely related to sequences of any World Health Organization (WHO) reference strains representing the 23 currently recognized genotypes. The minimum nucleotide divergence between the Menglian viruses and the most closely related reference strain, genotype D7, was 3.3% for the N gene and 3.0% for the H gene. A search of the databases of GenBank, WHO, and the Health Protection Agency Measles Nucleotide Surveillance showed that the Menglian viruses, together with the 2 older non-Menglian viruses, could be members of a new proposed measles genotype, d11. The new genotype designation will allow for better description of measles transmission patterns, especially in the Southeast Asian and Western Pacific regions.
Measles virus; new genotype; phylogenetic analysis; viruses; research
Molecular characterization of wild-type measles viruses in China during 1995-2004 demonstrated that genotype H1 was endemic and widely distributed throughout the country. H1-associated cases and outbreaks caused a resurgence of measles beginning in 2005. A total of 210,094 measles cases and 101 deaths were reported by National Notifiable Diseases Reporting System (NNDRS) and Chinese Measles Laboratory Network (LabNet) from 2006 to 2007, and the incidences of measles were 6.8/100,000 population and 7.2/100,000 population in 2006 and 2007, respectively. Five hundred and sixty-five wild-type measles viruses were isolated from 24 of 31 provinces in mainland China during 2006 and 2007, and all of the wild type virus isolates belonged to cluster 1 of genotype H1. These results indicated that H1-cluster 1 viruses were the predominant viruses circulating in China from 2006 to 2007. This study contributes to previous efforts to generate critical baseline data about circulating wild-type measles viruses in China that will allow molecular epidemiologic studies to help measure the progress made toward China's goal of measles elimination by 2012.
No effective therapeutic is currently in place for improved case management of severe measles or the rapid control of outbreaks. Through high-throughput screening, we recently identified a novel small-molecule class that potently blocks activity of the measles virus (MeV) RNA-dependent RNA polymerase (RdRp) complex in transient replicon assays. However, the nature of the block in RdRp activity and the physical target of the compound remained elusive. Through real-time reverse transcription-PCR analysis, we demonstrate that the lead compound AS-136A blocks viral RNA synthesis in the context of an infection. Adaptation of different MeV strains to growth in the presence of the compound identified three candidate hot spots for resistance that are located in conserved domains of the viral polymerase (L protein) subunit of the RdRp complex. Rebuilding of individual mutations in RdRp-driven reporter assays and recombinant MeV traced the molecular basis for resistance to specific mutations in L. Mutations responsible for resistance cluster in the immediate vicinity of the proposed catalytic center for phosphodiester bond formation and neighboring conserved domains of L, providing support for effective inhibition of a paramyxovirus RdRp complex through interaction of a nonnucleoside small-molecule inhibitor with the L protein. Resistance mutations are located in regions of L that are fully conserved among viral isolates, and recombinant MeV harboring individual resistance mutations show some delay in the onset of viral growth in vitro. Taken together, these data support the hypothesis that acquiring mutations in these L domains may reduce virus fitness.
Genetic analyses of viral samples from 74 laboratory confirmed measles cases occurring in Taiwan during 1992-2008 identified six viral genotypes D3, D5, D9, G2, H1 and H2. The most frequently detected genotype, H1, was associated with outbreaks in 1994 and 2002, and was the likely indigenous genotype in 1992. In response to the outbreaks, two catch-up campaigns were launched and a routine second dose of measles, mumps, and rubella vaccine at entry to elementary school was introduced. The vaccination campaigns successfully reduced the number of measles cases in Taiwan, and many of the more recent cases can be traced to importations, primarily from other Asian countries. A number of measles genotypes which were associated with outbreaks in other Asian countries were detected among the more recent cases. The more recent genotype H1 viruses had sequences that were identical to those currently circulating in China or associated with international importation of virus.
Measles morbidity and mortality decreased significantly after measles vaccine was introduced into China in 1965. From 1995 to 2004, average annual measles incidence decreased to 5.6 cases per 100,000 population following the establishment of a national two-dose regimen. Molecular characterization of wild-type measles viruses demonstrated that genotype H1 was endemic and widely distributed throughout the country in China during 1995-2004. A total of 124,865 cases and 55 deaths were reported from the National Notifiable Diseases Reporting System (NNDRS) in 2005, which represented a 69.05% increase compared with 2004. Over 16,000 serum samples obtained from 914 measles outbreaks and the measles IgM positive rate was 81%. 213 wild-type measles viruses were isolated from 18 of 31 provinces in China during 2005, and all of the isolates belonged to genotype H1. The ranges of the nucleotide sequence and predicted amino acid sequence homologies of the 213 genotype H1 strains were 93.4%-100% and 90.0%-100%, respectively. H1-associated cases and outbreaks caused the measles resurgence in China in 2005. H1 genotype has the most inner variation within genotype, it could be divided into 2 clusters, and cluster 1 viruses were predominant in China throughout 2005.
More than half of identified cases result from person-to-person transmission.
Human Nipah outbreaks recur in a specific region and time of year in Bangladesh. Fruit bats are the reservoir host for Nipah virus. We identified 23 introductions of Nipah virus into human populations in central and northwestern Bangladesh from 2001 through 2007. Ten introductions affected multiple persons (median 10). Illness onset occurred from December through May but not every year. We identified 122 cases of human Nipah infection. The mean age of case-patients was 27 years; 87 (71%) died. In 62 (51%) Nipah virus–infected patients, illness developed 5–15 days after close contact with another Nipah case-patient. Nine (7%) Nipah case-patients transmitted virus to others. Nipah case-patients who had difficulty breathing were more likely than those without respiratory difficulty to transmit Nipah (12% vs. 0%, p = 0.03). Although a small minority of infected patients transmit Nipah virus, more than half of identified cases result from person-to-person transmission. Interventions to prevent virus transmission from bats to humans and from person to person are needed.
Nipah virus; Bangladesh; disease transmission; respiratory tract infections; viruses; zoonoses; Pteropus; research
Emerging viruses in the paramyxovirus genus Henipavirus evade host antiviral responses via protein interactions between the viral V and W proteins and cellular STAT1 and STAT2 and the cytosolic RNA sensor MDA5. Polo-like kinase (PLK1) is identified as being an additional cellular partner that can bind to Nipah virus P, V, and W proteins. For both Nipah virus and Hendra virus, contact between the V protein and the PLK1 polo box domain is required for V protein phosphorylation. Results indicate that PLK1 is engaged by Nipah virus V protein amino acids 100 to 160, previously identified as being the STAT1 binding domain responsible for host interferon (IFN) signaling evasion, via a Thr-Ser-Ser-Pro motif surrounding residue 130. A distinct Ser-Thr-Pro motif surrounding residue 199 mediates the PLK1 interaction with Hendra virus V protein. Select mutations in the motif surrounding residue 130 also influenced STAT1 binding and innate immune interference, and data indicate that the V:PLK1 and V:STAT complexes are V mediated yet independent of one another. The effects of STAT1/PLK1 binding motif mutations on the function the Nipah virus P protein in directing RNA synthesis were tested. Remarkably, mutations that selectively disrupt the STAT or PLK1 interaction site have no effects on Nipah virus P protein-mediated viral RNA synthesis. Therefore, mutations targeting V protein-mediated IFN evasion will not alter the RNA synthetic capacity of the virus, supporting an attenuation strategy based on disrupting host protein interactions.
Live, attenuated measles virus (MeV) vaccine strains were generated by adaptation to cell culture. The genetic basis for the attenuation of the vaccine strains is unknown. We previously reported that adaptation of a pathogenic, wild-type MeV to Vero cells or primary chicken embryo fibroblasts (CEFs) resulted in a loss of pathogenicity in rhesus macaques. The CEF-adapted virus (D-CEF) contained single amino acid changes in the C and matrix (M) proteins and two substitutions in the shared amino terminal domain of the phosphoprotein (P) and V protein. The Vero-adapted virus (D-VI) had a mutation in the cytoplasmic tail of the hemagglutinin (H) protein.
In vitro assays were used to test the functions of the wild-type and mutant proteins. The substitution in the C protein of D-CEF decreased its ability to inhibit mini-genome replication, while the wild-type and mutant M proteins inhibited replication to the same extent. The substitution in the cytoplasmic tail of the D-VI H protein resulted in reduced fusion in a quantitative fusion assay. Co-expression of M proteins with wild-type fusion and H proteins decreased fusion activity, but the mutation in the M protein of D-CEF did not affect this function. Both mutations in the P and V proteins of D-CEF reduced the ability of these proteins to inhibit type I and II interferon signaling.
Adaptation of a wild-type MeV to cell culture selected for genetic changes that caused measurable functional differences in viral proteins.
The presence of measles virus (MV) RNA in bowel tissue from children with autism spectrum disorders (ASD) and gastrointestinal (GI) disturbances was reported in 1998. Subsequent investigations found no associations between MV exposure and ASD but did not test for the presence of MV RNA in bowel or focus on children with ASD and GI disturbances. Failure to replicate the original study design may contribute to continued public concern with respect to the safety of the measles, mumps, and rubella (MMR) vaccine.
The objective of this case-control study was to determine whether children with GI disturbances and autism are more likely than children with GI disturbances alone to have MV RNA and/or inflammation in bowel tissues and if autism and/or GI episode onset relate temporally to receipt of MMR. The sample was an age-matched group of US children undergoing clinically-indicated ileocolonoscopy. Ileal and cecal tissues from 25 children with autism and GI disturbances and 13 children with GI disturbances alone (controls) were evaluated by real-time reverse transcription (RT)-PCR for presence of MV RNA in three laboratories blinded to diagnosis, including one wherein the original findings suggesting a link between MV and ASD were reported. The temporal order of onset of GI episodes and autism relative to timing of MMR administration was examined. We found no differences between case and control groups in the presence of MV RNA in ileum and cecum. Results were consistent across the three laboratory sites. GI symptom and autism onset were unrelated to MMR timing. Eighty-eight percent of ASD cases had behavioral regression.
This study provides strong evidence against association of autism with persistent MV RNA in the GI tract or MMR exposure. Autism with GI disturbances is associated with elevated rates of regression in language or other skills and may represent an endophenotype distinct from other ASD.
The duration of mumps virus RNA detection was studied during a mumps outbreak in a highly vaccinated university population. Seven of the eight reverse transcription-PCR-positive specimens were collected during the first 3 days of parotitis, suggesting that viral shedding is minimal after the first 3 days of symptoms.
Importation of viruses from other continents caused prolonged circulation and large outbreaks in the WHO European Region.
During 2005–2006, nine measles virus (MV) genotypes were identified throughout the World Health Organization European Region. All major epidemics were associated with genotypes D4, D6, and B3. Other genotypes (B2, D5, D8, D9, G2, and H1) were only found in limited numbers of cases after importation from other continents. The genetic diversity of endemic D6 strains was low; genotypes C2 and D7, circulating in Europe until recent years, were no longer identified. The transmission chains of several indigenous MV strains may thus have been interrupted by enhanced vaccination. However, multiple importations from Africa and Asia and virus introduction into highly mobile and unvaccinated communities caused a massive spread of D4 and B3 strains throughout much of the region. Thus, despite the reduction of endemic MV circulation, importation of MV from other continents caused prolonged circulation and large outbreaks after their introduction into unvaccinated and highly mobile communities.
measles virus; molecular epidemiology; WHO European Region; years 2005-2006; research
The mumps virus is a negative-strand RNA virus in the family Paramyxoviridae. Mumps infection results in an acute illness with symptoms including fever, headache, and myalgia, followed by swelling of the salivary glands. Complications of mumps can include meningitis, deafness, pancreatitis, orchitis, and first-trimester abortion. Laboratory confirmation of mumps infection can be made by the detection of immunoglobulin M-specific antibodies to mumps virus in acute-phase serum samples, the isolation of mumps virus in cell culture, or by detection of the RNA of the mumps virus by reverse transcription (RT)-PCR. We developed and validated a multiplex real-time RT-PCR assay for rapid mumps diagnosis in a clinical setting. This assay used oligonucleotide primers and a TaqMan probe targeting the mumps SH gene, as well as primers and a probe that targeted the human RNase P gene to assess the presence of PCR inhibitors and as a measure of specimen quality. The test was specific, since it did not amplify a product from near-neighbor viruses, as well as sensitive and accurate. Real-time RT-PCR results showed 100% correlation with results from viral culture, the gold standard for mumps diagnostic testing. Assay efficiency was over 90% and displayed good precision after performing inter- and intraassay replicates. Thus, we have developed and validated a molecular method for rapidly diagnosing mumps infection that may be used to complement existing techniques.
Transmission of this virus highlights the need for infection control strategies for resource-poor settings.
An encephalitis outbreak was investigated in Faridpur District, Bangladesh, in April–May 2004 to determine the cause of the outbreak and risk factors for disease. Biologic specimens were tested for Nipah virus. Surfaces were evaluated for Nipah virus contamination by using reverse transcription–PCR (RT-PCR). Thirty-six cases of Nipah virus illness were identified; 75% of case-patients died. Multiple peaks of illness occurred, and 33 case-patients had close contact with another Nipah virus patient before their illness. Results from a case-control study showed that contact with 1 patient carried the highest risk for infection (odds ratio 6.7, 95% confidence interval 2.9–16.8, p<0.001). RT-PCR testing of environmental samples confirmed Nipah virus contamination of hospital surfaces. This investigation provides evidence for person-to-person transmission of Nipah virus. Capacity for person-to-person transmission increases the potential for wider spread of this highly lethal pathogen and highlights the need for infection control strategies for resource-poor settings.
Nipah virus; disease outbreak; disease transmission (horizontal); Bangladesh; research
This report describes the genetic characterization of 297 wild-type measles viruses that were isolated in 24 provinces of China between 1995 and 2003. Phylogenetic analysis of the N gene sequences showed that all of the isolates belonged to genotype H1 except 3 isolates, which were genotype A. The nucleotide sequence and predicted amino acid homologies of the 294-genotype H1 strains were 94.7%–100% and 93.3%–100%, respectively. The genotype H1 isolates were divided into 2 clusters, which differed by approximately 2.9% at the nucleotide level. Viruses from both clusters were distributed throughout China with no apparent geographic restriction and multiple co-circulating lineages were present in many provinces. Even though other measles genotypes have been detected in countries that border China, this report shows that genotype H1 is widely distributed throughout the country and that China has a single, endemic genotype. This important baseline data will help to monitor the progress of measles control in China.
An oligonucleotide microarray hybridization method for identification of most known measles virus (MV) genotypes was developed. Like the conventional genotyping method, the microarray relied on detecting sequence differences in the 450-nucleotide region coding for the COOH-terminal 150 amino acids of the nucleoprotein (N). This region was amplified using PCR primers binding to all known MV genotypes. The microarray included 71 pairs of oligonucleotide probes (oligoprobes) immobilized on glass slides. Each pair consisted of a genotype-specific oligoprobe, which matched the sequence of only one target genotype, and a control oligoprobe, which contained mismatches at the nucleotide positions unique to this genotype. A pattern recognition algorithm based on cluster analysis of the ratios of hybridization signals from specific and control oligoprobes was used to identify the specific MV genotype. Following the initial validation, the method was used for rapid genotyping of two panels of coded samples. The results of this study showed good sensitivity (90.7%), specificity (100%), and genotype agreement (91.8%) for the new method compared to the results of genotyping conducted using phylogenetic analysis of viral sequences of the C terminus of the N gene. In addition, the microarray demonstrated the ability to identify potential new genotypes of MV based on the similarity of their hybridization patterns with those of known MV genotypes.
Surveillance of measles virus detected an epidemiologic link between a refugee from Kenya and a Dutch tourist in New Jersey, USA. Identical genotype B3 sequences from patients with contemporaneous cases in the United States, Canada, and Mexico in November and December 2005 indicate that Kenya was likely to have been the common source of virus.
measles; genotype; epidemiology; surveillance; dispatch