High genetic diversity of measles virus, World Health Organization European Region, 2005-2006

Genetic Characterizations and Molecular Evolution of the Measles Virus Genotype B3's Hemagglutinin (H) Gene in the Elimination Era

Measles virus (MeV) genotype B3 is one globally significant circulating genotype. Here, we present a systematic description of long-term evolutionary characterizations of the MeV genotype B3's hemagglutinin (H) gene in the elimination era. Our results show that the B3 H gene can be divided into two main sub-genotypes, and the highest intra-genotypic diversity was observed in 2004. MeV genotype B3's H gene diverged in 1976; its overall nucleotide substitution rate is estimated to be 5.697 × 10^-4 substitutions/site/year, and is slowing down. The amino acid substitution rate of genotype B3's H gene is also decreasing, and the mean effective population size has been in a downward trend since 2000. Selection pressure analysis only recognized a few sites under positive selection, and the number of positive selection sites is getting smaller. All of these observations may reveal that genotype B3's H gene is not under strong selection pressure, and is becoming increasingly conservative. MeV H-gene or whole-genome sequencing should be routine, so as to better elucidate the molecular epidemiology of MeV in the future.

Characterisation of measles after the introduction of the combined measles-mumps-rubella (MMR) vaccine in 2004 with focus on the laboratory data, 2016 to 2019 outbreak, Romania

Background

Since January 2016, a resurgence of measles in Romania has led to the third measles epidemic in the past 12 years; 64 deaths have been confirmed so far–the highest number of measles-related deaths since the measles-mumps-rubella (MMR) vaccine was introduced in 2004.

Aim

To provide an overview on the characterisation on measles in Romania after the introduction of the MMR vaccine with focus on the current outbreak, laboratory and molecular analysis.

Methods

We performed an analysis of measles incidence and mortality after the introduction of MMR vaccination and a retrospective study using serological and molecular data in three consecutive outbreaks with focus on the current outbreak.

Results

In the current outbreak, 17,533 measles cases were notified to the national surveillance system, 93% were unvaccinated. Measles virus was isolated from 429 samples and 283 were genotyped. Genotype B3 was predominant (n = 269) and sporadic measles cases associated with D8 genotype (n = 9) were also observed; genotype D4 and D8 were identified in the previous two measles outbreaks. The detection of several distinct measles virus B3 genotypes suggests multiple virus importations to Romania.

Conclusion

The current outbreak is a consequence of insufficient vaccine coverage. Control measures were implemented to improve uptake of MMR vaccine, including administering the first MMR dose at a younger age (9–11 months) and offering catch-up vaccination to children that have not followed the recommended dosing schedule. More measures are needed to improve the surveillance performance and to achieve high routine MMR vaccination coverage.

Molecular characterization and evolutionary dynamics of measles virus sequences isolated from children in Lagos and Ibadan, South Western, Nigeria

Measles infection is endemic in Nigeria, with outbreaks occurring yearly. Genotype B3 is the dominant genotype and the only genotype characterized from Nigeria. The current study investigated the phylogenetic and Bayesian evolutionary dynamics of Nigerian measles virus Nucleoprotein (N) sequences isolated from Lagos and Ibadan, Nigeria. A total of 120 throat swab samples were analysed by RT-PCR and Sanger sequencing. Phylogenetic analysis and Bayesian demographic reconstructions were done using MEGA and BEAST software. Measles RNA positivity was 14.2% (17/120), age range 0-1 recorded the highest rate with 40.83%. Study sequences clustered within clade B3.1. The evolutionary rate of analysed B3 sequences was 1.108×10^-3, higher posterior density HPD interval (1.462×10^-3 - 7.886×10^-4)subs/site/year. The time to most recent common ancestor (T_MRC), was 1991. The Bayesian skyride analysis(BSP) of West African MV cladeB3.1, showed a stable, steady state population demography. This study has reemphasised the dominance of clade B3.1 in Nigeria. We have shown that clade B3.1 was recently introduced into circulation and has a slow population expansion. We advocate for the institution of molecular surveillance country wide in order to help monitor strain diversity and genetic evolution of Measles in Nigeria.

Measles Epidemics in Romania: Lessons for Public Health and Future Policy

Measles is a highly infectious viral disease that continues to be a challenge for many countries worldwide. Although significant improvements have been observed since the introduction of vaccines, measles remains endemic in Romania. Contributing factors include vaccine hesitancy, difficulties in delivering doses to the population, and even the lack of sufficient vaccine supplies. These problems are further exacerbated by an inadequate implementation of public health measures, ranging from inefficient communication programs to the absence of a legislative framework concerning immunization. Moreover, many of the recent outbreaks were associated with chains of transmission in other countries, thus making the control of measles in Romania relevant at an international level. As many difficulties exist, understanding the key factors that limit the success of public health programs may provide guidance in shaping future strategies. Because similar issues are being faced in various other countries, the management of measles in Romania offers valuable lessons for researchers and policy-makers alike.

Epidemiological Outbreaks of Measles Virus in Kazakhstan during 2015

This study involved epidemiological surveillance of the measles virus (MV) in the territory of the Republic of Kazakhstan during 2015-2016. We detected MV genotype D8 in this season of measles outbreak. A total of 2,341 cases were registered and 19 were identified by genotyping. Sixteen of these samples were attributed to subgroup A of genotype D8, while 3 imported cases were represented by genotypes B3 and H1. Analysis of vaccination coverage showed that a large group of infected people were not vaccinated or did not have a reliable report on their vaccination status. This issue might increase the morbidity rate among the healthy population in outbreak seasons. To prevent the incidence caused by this problem, we have successfully introduced epidemiologic measures for the control of measles.

Susceptibility to measles in migrant population: implication for policy makers

BACKGROUND

Despite a large measles outbreak is taking place in WHO European region, currently no data are available on measles immunization coverage in the asylum seeker and migrants hosted in this area.

METHODS

Two hundred and fifty-six migrants upon their arrival in Italy on March, April and May 2016 were screened for measles virus IgG antibodies by chemiluminescence immunoassay (Liaison XL analyzer, Diasorin, Italy). The virus susceptibility in this cohort, the differences between the official country reported and the observed measles immunization coverage and the impact of current measles outbreak on the asylum seekers hosted in the largest Asylum Seeker centres of Italy, were evaluated.

RESULTS

The prevalence of subjects with positive result for measles IgG antibodies ranged between 79.9% and 100%. In Senegal, Mali, Nigeria, Pakistan and Bangladesh, the measles IgG seroprevalence observed was greater than the vaccinal coverage reported by WHO after I dose of vaccine. Based on data regarding the II dose coverage, the ASs population presented a seroprevalence greater to that expected.

CONCLUSION

On the basis of the results obtained, extraordinary screening and vaccination campaigns in the migrant population, especially in the course of large outbreaks, could represent a resource to reach an adequate measles immunization coverage and to control this infectious disease.

Measles virus envelope pseudotyped lentiviral vectors transduce quiescent human HSCs at an efficiency without precedent

Hematopoietic stem cell (HSC)-based gene therapy trials are now moving toward the use of lentiviral vectors (LVs) with success. However, one challenge in the field remains: efficient transduction of HSCs without compromising their stem cell potential. Here we showed that measles virus glycoprotein-displaying LVs (hemagglutinin and fusion protein LVs [H/F-LVs]) were capable of transducing 100% of early-acting cytokine-stimulated human CD34⁺ (hCD34⁺) progenitor cells upon a single application. Strikingly, these H/F-LVs also allowed transduction of up to 70% of nonstimulated quiescent hCD34⁺ cells, whereas conventional vesicular stomatitis virus G (VSV-G)-LVs reached 5% at the most with H/F-LV entry occurring exclusively through the CD46 complement receptor. Importantly, reconstitution of NOD/SCIDγc^-/- (NSG) mice with H/F-LV transduced prestimulated or resting hCD34⁺ cells confirmed these high transduction levels in all myeloid and lymphoid lineages. Remarkably, for resting CD34⁺ cells, secondary recipients exhibited increasing transduction levels of up to 100%, emphasizing that H/F-LVs efficiently gene-marked HSCs in the resting state. Because H/F-LVs promoted ex vivo gene modification of minimally manipulated CD34⁺ progenitors that maintained stemness, we assessed their applicability in Fanconi anemia, a bone marrow (BM) failure with chromosomal fragility. Notably, only H/F-LVs efficiently gene-corrected minimally stimulated hCD34⁺ cells in unfractionated BM from these patients. These H/F-LVs improved HSC gene delivery in the absence of cytokine stimulation while maintaining their stem cell potential. Thus, H/F-LVs will facilitate future clinical applications requiring HSC gene modification, including BM failure syndromes, for which treatment has been very challenging up to now.

A measles outbreak in Sindh, Pakistan caused by a genotype B3 virus

Measles continues to be a major public health issue causing substantial outbreaks worldwide, mostly affecting young children. Molecular analysis of measles viruses provides important information on outbreak linkages and transmission pathways that can be helpful towards implementation of appropriate control programs. In Pakistan, the control of measles is still tenuous, and progress towards elimination has been irregular and challenging. In the 2013 measles outbreak we received 4,682 sera collected from suspected patients in 23 districts across Sindh. A total of 3,283 samples were confirmed measles positive using IgM ELISA with the highest infection rate in children aged 1-12 months. Males were more affected than females and a visible peak was observed from January to April. Among the 3,283 cases, 59.1% were unvaccinated, 29.6% had received 1 dose and 10.3% had received 2 doses of measles vaccine while 0.85% had an unknown vaccination status. For genotype detection and phylogenetic analysis, 60 throat swab samples were collected from suspected patients below 15 years of age in eight districts of Sindh province. Forty four (73%; 44/60) throat swab samples were successfully genotyped using RT-PCR. Phylogenetic analyses based on partial sequences of the nucleocapsid protein gene revealed that all Pakistani measles virus strains belonged to genotype B3 and were closely related to those isolated from neighboring countries such as Iran, Afghanistan (99.1-100%) and India with 98.6 - 99.6% nucleotide homology. This is the first report on the phylogenetic analysis of measles B3 genotype strains from Pakistan and highlights the need for strengthening the surveillance systems and improving immunization coverage across the country.

Molecular surveillance of measles and rubella in the WHO European Region: new challenges in the elimination phase

BACKGROUND

The WHO European Region (EUR) has adopted the goal of eliminating measles and rubella but individual countries perform differently in achieving this goal. Measles virus spread across the EUR by mobile groups has recently led to large outbreaks in the insufficiently vaccinated resident population. As an instrument for monitoring the elimination process and verifying the interruption of endemic virus transmission, molecular surveillance has to provide valid and representative data. Irrespective of the country's specific situation, it is required to ensure the functionality of the laboratory surveillance that is supported by the WHO Global Measles and Rubella Laboratory Network.

AIMS

To investigate whether the molecular surveillance in the EUR is adequate for the challenges in the elimination phase, we addressed the quality assurance of molecular data, the continuity and intensity of molecular monitoring, and the analysis of transmission chains.

SOURCES

Published articles, the molecular External Quality Assessment Programme of the WHO, the Centralized Information System for Infectious Diseases of the WHO EUR and the WHO Measles and Rubella Nucleotide Surveillance databases served as information sources.

CONTENT

Molecular proficiency testing conducted by the WHO in 2016 has shown that the expertise for measles and rubella virus genotyping exists in all parts of the EUR. The analysis of surveillance data reported nationally to the WHO in 2013-2016 has revealed some countries with outbreaks but not sufficiently representative molecular data. Long-lasting supranational MV transmission chains were identified.

IMPLICATIONS

A more systematic molecular monitoring and recording of the transmission pattern for the whole EUR could help to create a meaningful picture of the elimination process.

Antigenic Drift Defines a New D4 Subgenotype of Measles Virus

The measles virus hemagglutinin (MeV-H) protein is the main target of protective neutralizing antibodies. Using a panel of monoclonal antibodies (MAbs) that recognize known major antigenic sites in MeV-H, we identified a D4 genotype variant that escapes neutralization by MAbs targeting the neutralizing epitope (NE) antigenic site. By site-directed mutagenesis, L249P was identified as the critical mutation disrupting the NE in this genotype D4 variant. Forty-two available D4 genotype gene sequences were subsequently analyzed and divided into 2 groups according to the presence or absence of the L249P MeV-H mutation. Further analysis of the MeV-N gene sequences of these 2 groups confirmed that they represent clearly definable, sequence-divergent D4 subgenotypes, which we named subgenotypes D4.1 and D4.2. The subgenotype D4.1 MeVs were isolated predominantly in Kenya and Ethiopia, whereas the MAb-resistant subgenotype D4.2 MeVs were isolated predominantly in France and Great Britain, countries with higher vaccine coverage rates. Interestingly, D4.2 subgenotype viruses showed a trend toward diminished susceptibility to neutralization by human sera pooled from approximately 60 to 80 North American donors. Escape from MAb neutralization may be a powerful epidemiological surveillance tool to monitor the evolution of new MeV subgenotypes.IMPORTANCE Measles virus is a paradigmatic RNA virus, as the antigenic composition of the vaccination has not needed to be updated since its discovery. The vaccine confers protection by inducing neutralizing antibodies that interfere with the function of the hemagglutinin protein. Viral strains are indistinguishable serologically, although characteristic nucleotide sequences differentiate 24 genotypes. In this work, we describe a distant evolutionary branch within genotype D4. Designated subgenotype D4.2, this virus is distinguishable by neutralization with vaccine-induced monoclonal antibodies that target the neutralizing epitope (NE). The subgenotype D4.2 viruses have a higher predominance in countries with intermediary levels of vaccine coverage. Our studies demonstrate that subgenotype D4.2 lacks epitopes associated with half of the known antigenic sites, which significantly impacts our understanding of measles virus evolution.

Characterization of measles virus strains circulating in Southern Italy (Palermo area, Sicily) between 2010 and 2011

Measles virus (MV) was classified in 24 genotypes that show a distinct geographic distribution. Genotypes contain multiple distinct lineages. In 2011 large outbreaks of measles occurred in Italy and in many European countries. Aims of this study are to analyze the intra-genotype variability and to follow the importation and the spread of new MV strains in Sicily. A fragment of 450 bps of MV C-terminal nucleoprotein was sequenced from sera of 73 Sicilian patients with symptomatic measles infections, occurred between 2010 and 2011. Five MV strains were D4 genotype and 68 were D8 genotype. The MV/D4 sequences were related to MV/D4-Enfield variant. Two lineages of MV/D8 genotypes, related to MV/D8-Villupuram variant and to a strain found in Birmingham in 2006 respectively, were identified. This is the first study that reports the co-circulation of different MV genotypes and lineages in Sicily suggesting multiple origins of the outbreak that occurred during 2010 and 2011 years.

Epidemiologic and laboratory surveillance of the measles outbreak in the Federation of Bosnia and Herzegovina, February 2014-April 2015

A measles outbreak with two epidemic waves involving 4649 probable and laboratory-confirmed cases was recorded in six out of ten cantons of the Federation of Bosnia and Herzegovina between February 2014 and April 2015. The majority of the patients had never received measles vaccination (3115/4649, 67.00%), and the vaccination status of another 23% was unknown (1066/4649). A total of 281 blood samples were tested serologically. Virus detection was performed using 44 nasopharyngeal swabs. About 57% (161/281) of the laboratory-investigated sera were immunoglobulin M positive, and 95% (42/44) of the swabs were reverse transcriptase-PCR positive. Phylogenetic analysis of sequences obtained from 30 swab samples showed circulation of two variants of genotype D8, but no genotype D4 strains as detected in 2007. Similar involvement of all age groups indicates a problem with vaccine refusal resulting from antivaccination activities in addition to gaps in immunization coverage during the war and postwar period (1992-1998). Differences in ethnicity, vaccine coverage, compliance with review policies of vaccination records and potentially also travel habits may partially explain why only six of ten cantons were affected by the outbreak. The second epidemic wave may in part be due to large-scale migrations due to catastrophic floods in 2014. As a result of the epidemic, 6- to 12-month-old children may now be vaccinated against measles during outbreaks, and public health recommendations for interventions have been strengthened. Additional efforts are required to implement the measures throughout the cantons.

An ongoing measles outbreak in the Federation of Bosnia and Herzegovina, 2014 to 2015

Between January 2014 and the beginning of February 2015, the Federal Institute of Public Health in the Federation of Bosnia and Herzegovina has reported 3,804 measles cases. Notable transmission has been observed in three Central Bosnia Canton municipalities: Bugojno, Fojnica and Travnik. Most cases were unvaccinated 2,680 (70%) or of unknown vaccination status 755 (20%). Health authorities have been checking vaccination records and performing necessary prevention measures. The epidemic is still ongoing.

Spotlight on measles in Italy: why outbreaks of a vaccine-preventable infection continue in the 21st century

Measles is a serious infectious disease that can lead to significant morbidity and mortality. Remarkable progress has been made through measles vaccination in reducing the number of people dying from measles. In the last years, concerns about the safety of vaccines have led to decline in immunization coverage rates and new outbreaks of measles in many European countries, including Italy. We believe that it is important to reinforce the message that measles vaccine is safe and highly effective through appropriate information campaigns and public awareness.

Measles elimination in Italy: data from laboratory activity, 2011-2013

BACKGROUND

The European Regional Office of the World Health Organization developed a strategic approach to halt the indigenous transmission of measles in its 53 Member States by 2015, World Health Organization [1]. Many European countries, including Italy began the implementation of national programs to reach this goal.

OBJECTIVES

To describe and discuss the results of laboratory activity in measles surveillance, performed from January 2011 to December 2013 by the Italian National Reference Laboratory for Measles and Rubella.

STUDY DESIGN

Samples of suspected measles cases were collected from different Italian regions to confirm clinical diagnosis. Anti-measles IgM antibodies detection by Enzyme-Linked Immunosorbent Assay and/or molecular detection by Reverse Transcriptase-Polymerase Chain Reaction assay were performed. Positive samples were sequenced for viral characterization.

RESULTS AND CONCLUSIONS

According to results from the National Reference Laboratory's activity urine and blood seem to be the best specimens for measles laboratory surveillance. Phylogenetic analysis revealed a co-circulation of the genotypes D4 and D8 during the reviewed period, a cluster of B3 and sporadic cases of D9 and H1.

Molecular epidemiology of measles virus infection in Shanghai in 2000-2012: the first appearance of genotype D8

Purpose

The purpose of this study was to identify measles virus in Shanghai in 2012 and study the genotype trend of measles virus epidemic strains during 2000–2012.

Methods

Nose and throat swab specimens were collected from 34 suspected measles cases in Shanghai. Measles virus was isolated using Vero-SLAM cells (African green monkey kidney cells/lymphoid signal activating factor-transfected African green monkey kidney cells). The 450 bp of C terminus of the N gene and the entire hemagglutinin gene sequence was amplified using RT-PCR. Phylogenetic analysis was performed by comparing the seven measles strains in Shanghai with the reference strains for H1a, H1b and D8 genotypes, as well as the Chinese measles virus vaccine strain.

Results

Seven measles viruses strains were isolated from the 34 throat swap specimens. Six strains were genotype H1a, which is the predominant strain in China and one strain was genotype D8, which is the first imported strain since 2000. All these seven strains maintained most of the glycosylation sites except subtype H1a, which lost one glycosylation site.

Conclusion

Since 2000, measles virus strains in Shanghai are consistent with measles virus from other provinces in China with H1a being the predominant genotype. This study is also the first report of genotype D8 strain in Shanghai. All strains maintained their glycosylation sites except H1a that lost one glycosylation site. These strains could still be neutralized by the Chinese measles vaccine. We suggest that Shanghai Center for Disease Control laboratories should strengthen their approaches to monitor measles cases to prevent further spread of imported strains.

Wild-type measles viruses with non-standard genome lengths

The length of the single stranded, negative sense RNA genome of measles virus (MeV) is highly conserved at 15,894 nucleotides (nt). MeVs can be grouped into 24 genotypes based on the highly variable 450 nucleotides coding for the carboxyl-terminus of the nucleocapsid protein (N-450). Here, we report the genomic sequences of 2 wild-type viral isolates of genotype D4 with genome lengths of 15,900 nt. Both genomes had a 7 nt insertion in the 3′ untranslated region (UTR) of the matrix (M) gene and a 1 nt deletion in the 5′ UTR of the fusion (F) gene. The net gain of 6 nt complies with the rule-of-six required for replication competency of the genomes of morbilliviruses. The insertions and deletion (indels) were confirmed in a patient sample that was the source of one of the viral isolates. The positions of the indels were identical in both viral isolates, even though epidemiological data and the 3 nt differences in N-450 between the two genomes suggested that the viruses represented separate chains of transmission. Identical indels were found in the M-F intergenic regions of 14 additional genotype D4 viral isolates that were imported into the US during 2007–2010. Viral isolates with and without indels produced plaques of similar size and replicated efficiently in A549/hSLAM and Vero/hSLAM cells. This is the first report of wild-type MeVs with genome lengths other than 15,894 nt and demonstrates that the length of the M-F UTR of wild-type MeVs is flexible.

Transmission and molecular characterisation of wild measles virus in Romania, 2008 to 2012

Molecular characterisation of measles virus is a powerful tool for tracing transmission. Genotyping may prove the absence of endemic circulation of measles virus, i.e. transmission for more than 12 months, which is one of the criteria for verifying elimination of the disease. We have genetically characterised measles viruses detected in Romania from 2008 to 2012, focusing on the recent outbreaks from 2010 to 2012 that affected mainly groups with limited access to healthcare and schools. The findings emphasise the importance of genotyping during the different phases of an outbreak. A total of 8,170 cases were notified, and 5,093 (62%) of the 7,559 possible cases were serologically confirmed. RT-PCR was performed for 104 samples: from the 101 positive samples obtained from sporadic measles cases or clusters from different counties, 73 were genotyped. Sporadic measles cases associated with D4 and D5 viruses were observed from2008 to 2009. Genotype D4-Manchester was predominant in 2011 and 2012. In addition, the related variant D4-Maramures and MVs/Limoges.FRA/17.10[D4] and a few D4-Hamburg strains were detected. The detection of several distinct MV-D4 genotypes suggests multiple virus importations to Romania. The outbreak associated with D4 genotype is the second largest outbreak in Romania in less than 10 years.

Molecular epidemiology of measles virus in Italy, 2002-2007

Background

The European Regional Office of the World Health Organization (WHO/Europe) developed a strategic approach to halt the indigenous transmission of measles in its 53 Member States by 2015. In view of the goal of measles elimination, it is of great importance to assess the circulation of wild-type measles virus (MV). Genetic analysis is indispensable to understand the epidemiology of measles.

Methods

Urine and saliva samples were collected between May 2002 and December 2007, in order to find the origins and routes of wild type measles virus circulation. RT-PCR was performed on a total of 414 clinical samples of patients from different Italian regions. The results confirmed the genome presence in 199 samples, out of which 179 were sequenced. The sequences were genotyped by comparing the fragment coding for the carboxyl terminus of the nucleoprotein (450 nucleotides) with that one of the WHO reference strains.

Results

From the year 2002 to the year 2007 phylogenetic analysis of measles sequences showed a predominant circulation of the D7 genotype in the Italian territory for the years 2002–2004. This genotype was replaced by D4 and B3 genotypes in the biennium 2006–2007. During the same period C2, A, D5 and D8 genotypes were also detected.

Conclusions

Genetic characterization of wild-type MV provides a means to study the transmission pathways of the virus, and is an essential component of laboratory-based surveillance. Knowledge of currently circulating measles virus genotype in Italy will help in monitoring the success of the measles elimination programme and will contribute to evaluate the effectiveness of future vaccination campaigns.

Lentiviral vectors displaying modified measles virus gp overcome pre-existing immunity in in vivo-like transduction of human T and B cells

Gene transfer into quiescent T and B cells is important for gene therapy and immunotherapy approaches. Previously, we generated lentiviral vectors (LVs) pseudotyped with Edmonston (Ed) measles virus (MV) hemagglutinin (H) and fusion (F) glycoproteins (H/F-LVs), which allowed efficient transduction of quiescent human T and B cells. However, a major obstacle in the use of H/F-LVs in vivo is that most of the human population is vaccinated against measles. As the MV humoral immune response is exclusively directed against the H protein of MV, we mutated the two dominant epitopes in H, Noose, and NE. LVs pseudotyped with these mutant H-glycoproteins escaped inactivation by monoclonal antibodies (mAbs) but were still neutralized by human serum. Consequently, we took advantage of newly emerged MV-D genotypes that were less sensitive to MV vaccination due to a different glycosylation pattern. The mutation responsible was introduced into the H/F-LVs, already mutated for Noose and NE epitopes. We found that these mutant H/F-LVs could efficiently transduce quiescent lymphocytes in the presence of high concentrations of MV antibody-positive human serum. Finally, upon incubation with total blood, mimicking the in vivo situation, the mutant H/F-LVs escaped MV antibody neutralization, where the original H/F-LVs failed. Thus, these novel H/F-LVs offer perspectives for in vivo lymphocyte-based gene therapy and immunotherapy.

Measles outbreak in an asylum-seekers' shelter in Germany: comparison of the implemented with a hypothetical containment strategy

In order to contain a measles outbreak in a German asylum-seekers' shelter, serological testing of all residents was performed, followed by selective vaccination of those with negative test results/not tested. In this paper we describe the outbreak epidemiologically and then compare the implemented strategy with a hypothetical mass vaccination of all individuals unvaccinated or with unknown vaccination status born after 1970 as recommended by the German Standing Committee on Vaccination in terms of potentially avoided cases, logistics, and costs. Three hundred (70%) residents participated in the serological testing, of which 39 (13%) were seronegative. In total, 144 individuals were eligible for vaccination, while a mass vaccination would have targeted 359 persons. However, serological testing was time- and personnel consuming and revealed several logistical problems. Its costs amounted to €90 000, double that of mass vaccination that additionally might have avoided three of the eight cases. Mass vaccination seems the preferred measure for measles outbreak control in such settings.

Spread of measles virus D4-Hamburg, Europe, 2008-2011

A new strain of measles virus, D4-Hamburg, was imported from London to Hamburg in December 2008 and subsequently spread to Bulgaria, where an outbreak of >24,300 cases was observed. We analyzed spread of the virus to demonstrate the importance of addressing hard-to-reach communities within the World Health Organization European Region regarding access to medical care and vaccination campaigns. The D4-Hamburg strain appeared during 2009-2011 in Poland, Ireland, Northern Ireland, Austria, Greece, Romania, Turkey, Macedonia, Serbia, Switzerland, and Belgium and was repeatedly reimported to Germany. The strain was present in Europe for >27 months and led to >25,000 cases in 12 countries. Spread of the virus was prevalently but not exclusively associated with travel by persons in the Roma ethnic group; because this travel extends beyond the borders of any European country, measures to prevent the spread of measles should be implemented by the region as a whole.

Biological feasibility of measles eradication

Because of the success of global measles control programs, the World Health Organization (WHO), along with its partner agencies, is once again considering the possibility of setting a target date for measles eradication. Measles would be the fourth viral agent to be eradicated joining the successful programs to eradicate smallpox and rinderpest virus, and the continuing effort to eradicate polio virus. A description of the recent progress toward measles eradication was recently published as a supplement in the Journal of Infectious Diseases (15 July, 2011, 204 (Suppl. 1)) and the reader is referred to this document for a detailed summary of the global status of measles control. This review will focus on the biologic and virologic aspects of measles eradication.

Closer to the goal: efforts in measles elimination in Germany 2010

Increasing 2-dose vaccination coverage has led to an interruption of endemic measles virus circulation in Germany. However, outbreaks after virus importation still occur and contribute to international transmission chains. Between 2003 and 2009, annual measles incidence ranged between 0.2 and 2.8 per 100,000 population. Immunization gaps have been identified especially in secondary-school students and young adults, which is also reflected by a shift in age distribution of reported measles cases toward older age groups. Stronger political commitment and standardized guidelines for outbreak containment were put in place in Germany in the past years, but the last step toward measles elimination cannot be made until the number of susceptible individuals has been further reduced. In addition to routine childhood vaccination, supplementary immunization activities are needed targeting school students and young adults to close critical immunization gaps. Intensification of public awareness and sound information on vaccinations are necessary to convince skeptics and remind the forgetful.

Molecular genotyping and epidemiology of measles virus transmission in the World Health Organization European Region, 2007-2009

BACKGROUND

In 2002, the World Health Organization (WHO) adopted a goal to eliminate measles in the European Region by 2010. Measles elimination is defined as the interruption of indigenous measles virus (MV) transmission. The molecular epidemiology of MV transmission in the WHO European Region was studied through the investigation of reported cases and outbreaks to monitor the region's progress toward its measles elimination goal.

METHODS

National and regional laboratories performed molecular characterization of MV detected between 2007 and 2009 in the WHO European Region. To document indigenous transmission and importations into the region, we analyzed genotyping results and epidemiological data on measles outbreaks reported by the member states.

RESULTS

Since 2007, MV genotype D6 has not been reported in the WHO European Region, suggesting that its chains of transmission have been interrupted, whereas several other MV genotypes are still circulating. Although several European countries have already interrupted indigenous MV transmission, genotyping showed that 3 endemic MV transmission chains have been reestablished in other countries.

CONCLUSIONS

The WHO European Region 2010 goal will not be met, as indigenous transmission of MV has not been interrupted. As the region begins to document its process of elimination verification to monitor progress toward the goal, countries will need to ensure that genotyping is performed in all measles outbreaks.

Molecular and phylogenetic analysis of Greek measles 2010 strains

Although elimination of measles virus (MV) by 2010 was a revised target, a new epidemic has been ongoing in Greece and other European countries. The purpose of this study was the molecular and phylogenetic analysis of the Greek MV circulating strain. Twenty-four MV strains isolated from clinical samples during the 2010 outbreak were genotyped and studied in terms of nucleotide variation and phylogeny. All of the detected viruses were of the D4 genotype, which is circulating in Greece in the Roma population of Bulgarian nationality, the Greek Roma population and the Greek non-minority population, as well as in other EU countries. Phylogenetic analysis revealed that these viruses belonged to subgroup 4 of D4 MV strains. It is essential to continue epidemiological surveillance of measles in Greece to monitor the transmission pattern of the virus and the effectiveness of measles immunization, which eventually will lead to its elimination.

Molecular Epidemiology of Measles Virus before and after the 2003 Mass Vaccination Campaign for Measles/Rubella in Iran

BACKGROUND

Molecular epidemiology of measles virus (MV) is important, not only to measure the success of measles vaccination programs but also to monitor the circulation and elimination of the virus worldwide. In this study, we compared MV obtained from patients before the 2003 mass vaccination MR campaign and viruses detected after 2003 until 2008 in Iran.

METHODS

The nucleoprotein (N) gene of 29 MV strains circulating in Iran between 2002 and 2008 were amplified by RT-PCR and subjected to sequence and phylogenetic analysis.

RESULTS

Molecular characterization of MV studied here revealed that although the outbreaks in Iran were associated with MV genotype D4, the isolated viruses clearly belonged to several different lineages. Maximum and minimum homology within the 29 Iranian strains in our study was100% and 94.9% within the carboxyl terminus of the N gene, respectively. Using ClustalX program, the alignment of Iranian MV sequences showed nine lineages.

CONCLUSION

This study provides the usefulness of MV sequence analysis for the demonstration of local interruption of indigenous strain transmission as well as providing a valuable means for monitoring the elimination processes of MV control.

Measles virus glycoprotein-pseudotyped lentiviral vector-mediated gene transfer into quiescent lymphocytes requires binding to both SLAM and CD46 entry receptors

Gene transfer into quiescent T and B cells is of importance for gene therapy and immunotherapy approaches to correct hematopoietic disorders. Previously, we generated lentiviral vectors (LVs) pseudotyped with the Edmonston measles virus (MV) hemagglutinin and fusion glycoproteins (Hgps and Fgps) (H/F-LVs), which, for the first time, allowed efficient transduction of quiescent human B and T cells. These target cells express both MV entry receptors used by the vaccinal Edmonston strain, CD46 and signaling lymphocyte activation molecule (SLAM). Interestingly, LVs pseudotyped with an MV Hgp, blind for the CD46 binding site, were completely inefficient for resting-lymphocyte transduction. Similarly, SLAM-blind H mutants that recognize only CD46 as the entry receptor did not allow stable LV transduction of resting T cells. The CD46-tropic LVs accomplished vector-cell binding, fusion, entry, and reverse transcription at levels similar to those achieved by the H/F-LVs, but efficient proviral integration did not occur. Our results indicate that both CD46 and SLAM binding sites need to be present in cis in the Hgp to allow successful stable transduction of quiescent lymphocytes. Moreover, the entry mechanism utilized appears to be crucial: efficient transduction was observed only when CD46 and SLAM were correctly engaged and an entry mechanism that strongly resembles macropinocytosis was triggered. Taken together, our results suggest that although vector entry can occur through the CD46 receptor, SLAM binding and subsequent signaling are also required for efficient LV transduction of quiescent lymphocytes to occur.

Epidemiological and molecular assessment of a measles outbreak in a highly vaccinated population of northeast Italy

Two distinct measles outbreaks, unrelated from the epidemiological point of view but caused by genetically related strains, occurred in the Friuli Venezia Giulia region of northeastern Italy. Forty-two cases were reported during the period April-May 2008. In the first outbreak the index case was a teacher who introduced the virus into the Pordenone area, involving eight adolescents and young adults. The other concomitant outbreak occurred in the city of Trieste with 33 cases. The containment of the epidemics can be explained by the high MMR vaccine coverage in an area where the first dose was delivered to 93·4% and the second dose to 88·3% of the target children. Phylogenetic analysis of 14 measles virus strains showed that they belonged to a unique D4 genotype indistinguishable from the MVs/Enfield.GBR/14.07 strain, probably introduced from areas (i.e. Piedmont and Germany) where this genotype was present or had recently caused a large epidemic.

Revealing new measles virus transmission routes by use of sequence analysis of phosphoprotein and hemagglutinin genes

With improved measles virus (MV) control, the genetic variability of the MV-nucleoprotein hypervariable region (NP-HVR) decreases. Thus, it becomes increasingly difficult to determine the origin of a virus using only this part of the genome. During outbreaks in Europe and Africa, we found MV strains with identical NP-HVR sequences. However, these strains showed considerable diversity within a larger sequencing window based on concatenated MV phosphoprotein and hemagglutinin genes (P/H pseudogenes). In Belarus, Germany, Russia, and the Democratic Republic of Congo, the P/H pseudogenes provided insights into chains of transmission, whereas identical NP-HVR provided none. In Russia, for instance, the P/H pseudogene identified temporal clusters rather than geographical clusters, demonstrating the circulation and importation of independent variants rather than large local outbreaks lasting for several years, as suggested by NP-HVR. Thus, by extending the sequencing window for molecular epidemiology, a more refined picture of MV circulation was obtained with more clearly defined links between outbreaks and transmission chains. Our results also suggested that in contrast to the P gene, the H gene acquired fixed substitutions that continued to be found in subsequent outbreaks, possibly with consequences for its antigenicity. Thus, a longer sequencing window has true benefits both for the epidemiological surveillance of measles and for the better monitoring of viral evolution.

Comparison of laboratory diagnostic methods for measles infection and identification of measles virus genotypes in Hong Kong

The sensitivities of IgM detection, virus isolation, and RT-PCR for the diagnosis of measles infection were assessed using samples collected from confirmed measles cases from 2006 to 2009. The optimal timing of specimen collection and the preferred specimen type(s) for these tests were also determined. IgM detection showed highest sensitivity when serum samples were collected >or=5 days after rash onset. Virus isolation gave the highest sensitivity when samples were collected <or=3 days after rash onset, with nasopharyngeal aspirate being the best specimen type, followed by urine and throat/combined throat and nasal swab. The highest RT-PCR positive rate (81.0%) was obtained with serum samples collected <or=3 days after rash onset. RT-PCR positive rate of 100% was observed with throat/combined throat and nasal swab, urine and nasopharyngeal aspirate collected <or=16, 4-16, and 4-7 days after rash onset, respectively. The genotype of each measles case was confirmed by sequencing. It was shown that the predominant measles viruses detected in Hong Kong during 2006-2009 belonged to genotype H1 (subtype a) and these strains were related closely to those detected in China.

Description of two measles outbreaks in the Lazio Region, Italy (2006-2007). Importance of pockets of low vaccine coverage in sustaining the infection

BACKGROUND

Despite the launch of the national plan for measles elimination, in Italy, immunization coverage remains suboptimal and outbreaks continue to occur. Two measles outbreaks, occurred in Lazio region during 2006-2007, were investigated to identify sources of infection, transmission routes, and assess operational implications for elimination of the disease.

METHODS

Data were obtained from several sources, the routine infectious diseases surveillance system, field epidemiological investigations, and molecular genotyping of virus by the national reference laboratory.

RESULTS

Overall 449 cases were reported, sustained by two different stereotypes overlapping for few months. Serotype D4 was likely imported from Romania by a Roma/Sinti family and subsequently spread to the rest of the population. Serotype B3 was responsible for the second outbreak which started in a secondary school. Pockets of low vaccine coverage individuals (Roma/Sinti communities, high school students) facilitated the reintroduction of serotypes not endemic in Italy and facilitated the measles infection to spread.

CONCLUSIONS

Communities with low vaccine coverage represent a more serious public health threat than do sporadic susceptible individuals. The successful elimination of measles will require additional efforts to immunize low vaccine coverage population groups, including hard-to-reach individuals, adolescents, and young adults. An enhanced surveillance systems, which includes viral genotyping to document chains of transmission, is an essential tool for evaluating strategy to control and eliminate measles.

Measles resurgence associated with continued circulation of genotype H1 viruses in China, 2005

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.

Measles risk groups in Spain: implications for the European measles-elimination target

The European Region has set itself the goal of eliminating measles by 2010. Incidence has increased in recent years. This study sought to investigate outbreaks in Spain in the period 2005-2007, in order to identify measles-vulnerable groups and compare Spain to other European countries which have also had measles outbreaks. The pattern observed for Spain proved different to that of other European countries, i.e., whereas young adults and infants aged under 15 months were affected in Spain, children aged under 9 years comprised the predominant group in other European countries. Measles cases in Spain reflect low coverage when vaccination began, a pattern that could be repeated in neighbouring countries. Vaccination efforts should thus be targeted at vulnerable groups, namely: young adults; health professionals; travelling communities; and adopted infants and foreigners from countries with important pockets of susceptibles.

Molecular epidemiology of measles virus

Genetic characterization of wild-type measles viruses provides a means to study the transmission pathways of the virus and is an essential component of laboratory-based surveillance. Laboratory-based surveillance for measles and rubella, including genetic characterization of wild-type viruses, is performed throughout the world by the WHO Measles and Rubella Laboratory Network, which serves 166 countries in all WHO regions. In particular, the genetic data can help confirm the sources of virus or suggest a source for unknown-source cases as well as to establish links, or lack thereof, between various cases and outbreaks. Virologic surveillance has helped to document the interruption of transmission of endemic measles in some regions. Thus, molecular characterization of measles viruses has provided a valuable tool for measuring the effectiveness of measles control programs, and virologic surveillance needs to be expanded in all areas of the world and conducted during all phases of measles control.

Further efforts needed to achieve measles elimination in Germany: results of an outbreak investigation

OBJECTIVE

To determine morbidity and costs related to a large measles outbreak in Germany and to identify ways to improve the country's national measles elimination strategy.

METHODS

We investigated a large outbreak of measles in the federal state of North Rhine-Westphalia (NRW) that occurred in 2006 after 2 years of low measles incidence (< 1 case per 100,000). WHO's clinical case definition was used, and surveillance data from 2006 and 2001 were compared. All cases notified in Duisburg, the most severely affected city, were contacted and interviewed or sent a questionnaire. Health-care provider costs were calculated using information on complications, hospitalization and physician consultations.

FINDINGS

In NRW, 1749 cases were notified over a 48-week period. Compared with 2001, the distribution of cases shifted to older age groups (especially the 10-14 year group). Most cases (n = 614) occurred in Duisburg. Of these, 81% were interviewed; 15% were hospitalized and two died. Of the 464 for whom information was available, 80% were reported as unvaccinated. Common reasons for non-vaccination were parents either forgetting (36%) or rejecting (28%) vaccination. The average cost per measles case was estimated at 373 euros.

CONCLUSION

An accumulation of non-immune individuals led to this outbreak. The shift in age distribution has implications for the effectiveness of measles control and the elimination strategy in place. Immediate nationwide school-based catch-up vaccination campaigns targeting older age groups are needed to close critical immunity gaps. Otherwise, the elimination of measles in Germany and thus in Europe by 2010 will not be feasible.

Measles in Europe: an epidemiological assessment

BACKGROUND

Measles persists in Europe despite the incorporation of the measles vaccine into routine childhood vaccination programmes more than 20 years ago. Our aim was therefore to review the epidemiology of measles in relation to the goal of elimination by 2010.

METHODS

National surveillance institutions from 32 European countries submitted data for 2006-07. Data for age-group, diagnosis confirmation, vaccination, hospital treatment, the presence of acute encephalitis as a complication of disease, and death were obtained. 30 countries also supplied data about importation of disease. Clinical, laboratory-confirmed, and epidemiologically linked cases that met the requirements for national surveillance were analysed. Cases were separated by age: younger than 1 year, 1-4 years, 5-9 years, 10-14 years, 15-19 years, and older than 20 years. Countries with indigenous measles incidence per 100 000 inhabitants per year of 0, less than 0.1, 0.1-1, and more than 1 were grouped into categories of zero, low, moderate, and high incidence, respectively.

FINDINGS

For the 2 years of the study, 12 132 cases of measles were recorded with most cases (n=10 329; 85%) from five countries: Romania, Germany, UK, Switzerland, and Italy. Most cases were unvaccinated or incompletely vaccinated children; however, almost a fifth were aged 20 years or older. For the same 2 years, seven measles-related deaths were recorded. High measles incidence in some European countries revealed suboptimum vaccination coverage. Of the 210 cases that were reported as being imported, 117 (56%) came from another country within Europe and 43 (20%) from Asia.

INTERPRETATION

The suboptimum vaccination coverage raises serious doubts that the goal of elimination by 2010 can be attained. Achievement and maintenance of optimum vaccination coverage and improved surveillance are the cornerstones of the measles elimination plan for Europe.

Phylogenetic analysis of rubella virus strains from an outbreak in Madrid, Spain, from 2004 to 2005

An outbreak of rubella affected 460 individuals in 2004 and 2005 in the community of Madrid, Spain. Most of the patients were nonvaccinated Latin American immigrants or Spanish males. This study presents the first data on rubella virus genotypes in Spain. Forty selected clinical samples (2 urine, 5 serum, 3 blood, 2 saliva, and 28 pharyngeal exudate samples) from 40 cases were collected. The 739-nucleotide sequence recommended by the World Health Organization obtained from viral RNA in these samples was analyzed by using the MEGA v4.0 software. Seventeen isolates were obtained from 40 clinical samples from the outbreak, including two isolated from congenital rubella syndrome cases. Only viral RNA of genotype 1j was detected in both isolates and clinical specimens. Two variations in amino acids, G253C and T394S, which are involved in neutralization epitopes arose during the outbreak, but apparently there was no positive selection of either of them. The origin of the outbreak remains unknown because of poor virologic surveillance in Latin America and the African countries neighboring Spain. On the other hand, this is the first report of this genotype in Europe. The few published sequences of genotype 1j indicate that it comes from Japan and the Philippines, but there are no epidemiological data supporting this as the origin of the Madrid outbreak.

Diseases of poverty with high mortality in infants and children: malaria, measles, lower respiratory infections, and diarrheal illnesses

Malaria, measles, lower respiratory infections, and diarrheal illnesses are common pediatric medical problems that are often fatal in the context of extreme poverty. In nonpoor environments, however, these infections are controlled and managed in ways that minimize mortality. From a scientific perspective, genetic variation among microbes is a frequent and important component of their epidemiology, pathophysiology, treatment, and prevention. From a public health perspective, relatively simple measures can reduce the mortal effects of these diseases until successful vaccines become available and immunizations programs are established. Infants and children are especially vulnerable to poor outcomes from infections when undernutrition and other circumstances of poverty are present.

Genetic variability and mRNA editing frequencies of the phosphoprotein genes of wild-type measles viruses

The sequences of the nucleoprotein (N) and hemagglutinin (H) genes are routinely used for molecular epidemiologic studies of measles virus (MV). However, the amount of genetic diversity contained in other genes of MV has not been thoroughly evaluated. In this report, the nucleotide sequences of the phosphoprotein (P) genes from 34 wild-type strains representing 15 genotypes of MV were analyzed and found to be almost as variable as the H genes but less variable than the N genes. Deduced amino acid sequences of the three proteins encoded by the P gene, P, V and C, demonstrated considerably higher variability than the H proteins. Phylogenetic analysis showed the same tree topography for the P gene sequences as previously seen for the N and H genes. RNA editing of P gene transcripts affects the relative ratios of P and V proteins, which may have consequences for pathogenicity. Wild-type isolates produced more transcripts with more than one G insertion; however, there was no significant difference in the use of P and V open reading frames, suggesting that the relative amounts of P and V proteins in infected cells would be similar for both vaccine and wild-type strains.