Measles

Role of the Th1 and Th17 Pathway in Subacute Sclerosing Panencephalitis

Subacute sclerosing panencephalitis (SSPE) is a progressive and fatal disease caused by reactivation of a mutated measles virus in brain tissue. The process of reactivation is yet to be elucidated. In this study, the possible roles of the Th1 (interleukin [IL]-12, interferon [IFN]-γ) and the Th17 axis (IL-23, IL-17, IL-22), particularly of IL-17, in the pathogenesis of SSPE were investigated. Briefly, mononuclear cells from SSPE patients were stimulated using measles virus peptide, and the release of IL-12, IL-23, IL-22, IFN-γ, and IL-17 cytokines was measured using enzyme-linked immunosorbent assay and/or enzyme-linked immunosorbent spot assay (ELISpot). We found that in comparison to the mononuclear cells obtained from healthy donors, cells from SSPE patients exhibited increased levels of IL-12, IL-23, IL-17, IL-22, and IFN-γ cytokines in response to measles virus stimulation. However, the same result was not obtained with cytomegalovirus and phytohemagglutinin. Using flow cytometry, mononuclear cells obtained from SSPE patients and healthy controls were also analyzed for the presence of intracellular IL-17 in response to measles virus stimulation. On stimulation, the number of IL-17-positive cells were found to be higher among mononuclear cells obtained from the patients. In addition, the numbers of IL-17- and IFN-γ-positive cells were significantly increased in SSPE patients. In conclusion, this study demonstrates that both the IL-12/IFN-γ and the IL-23/IL-17/IL-22 pathways are functionally abnormal in SSPE pathogenesis. Targeting these pathways and their specific pro-inflammatory mediator production may provide a new strategy to suppress SSPE development.

Genotype-Specific Measles Transmissibility: A Branching Process Analysis

Background

Substantial heterogeneity in measles outbreak sizes may be due to genotype-specific transmissibility. Using a branching process analysis, we characterize differences in measles transmission by estimating the association between genotype and the reproduction number R among postelimination California measles cases during 2000-2015 (400 cases, 165 outbreaks).

Methods

Assuming a negative binomial secondary case distribution, we fit a branching process model to the distribution of outbreak sizes using maximum likelihood and estimated the reproduction number R for a multigenotype model.

Results

Genotype B3 is found to be significantly more transmissible than other genotypes (P = .01) with an R of 0.64 (95% confidence interval [CI], .48-.71), while the R for all other genotypes combined is 0.43 (95% CI, .28-.54). This result is robust to excluding the 2014-2015 outbreak linked to Disneyland theme parks (referred to as "outbreak A" for conciseness and clarity) (P = .04) and modeling genotype as a random effect (P = .004 including outbreak A and P = .02 excluding outbreak A). This result was not accounted for by season of introduction, age of index case, or vaccination of the index case. The R for outbreaks with a school-aged index case is 0.69 (95% CI, .52-.78), while the R for outbreaks with a non-school-aged index case is 0.28 (95% CI, .19-.35), but this cannot account for differences between genotypes.

Conclusions

Variability in measles transmissibility may have important implications for measles control; the vaccination threshold required for elimination may not be the same for all genotypes or age groups.

Increase in Infant Measles Deaths During a Nationwide Measles Outbreak-Mongolia, 2015-2016

BACKGROUND

Surveillance data from a large measles outbreak in Mongolia suggested increased case fatality ratio (CFR) in the second of 2 waves. To confirm the increase in CFR and identify risk factors for measles death, we enhanced mortality ascertainment and conducted a case-control study among infants hospitalized for measles.

METHODS

We linked national vital records with surveillance data of clinically or laboratory-confirmed infant (aged <12 months) measles cases with rash onset during March-September 2015 (wave 1) and October 2015-June 2016 (wave 2). We abstracted medical charts of 95 fatal cases and 273 nonfatal cases hospitalized for measles, matched by age and sex. We calculated adjusted matched odds ratios (amORs) and 95% confidence intervals (CIs) for risk factors.

RESULTS

Infant measles deaths increased from 3 among 2224 cases (CFR: 0.13%) in wave 1 to 113 among 4884 cases (CFR: 2.31%) in wave 2 (P < .001). Inpatient admission, 7-21 days before measles rash onset, for pneumonia or influenza (amOR: 4.5; CI, 2.6-8.0), but not other diagnoses, was significantly associated with death.

DISCUSSION

Measles infection among children hospitalized with respiratory infections likely increased deaths due to measles during wave 2. Preventing measles virus nosocomial transmission likely decreases measles mortality.

Additional Evidence on Serological Correlates of Protection against Measles: An Observational Cohort Study among Once Vaccinated Children Exposed to Measles

To assess correlates of protection against measles and against subclinical measles virus (MV) infection, we recruited once-vaccinated children from geographic regions associated with increased MV circulation and/or at schools with low vaccination coverage in the Netherlands. Paired blood samples were collected shortly after onset of the measles outbreak and after the outbreak. A questionnaire was used to document the likelihood of exposure to MV and occurrence of measles-like symptoms. All blood samples were tested for MV-specific antibodies with five different assays. Correlates of protection were assessed by considering the lowest neutralizing antibody levels in children without MV infection, and by ROC analyses. Among 91 participants, two seronegative children (2%) developed measles, and an additional 19 (23%) experienced subclinical MV infection. The correlate of protection against measles was lower than 0.345 IU/mL. We observed a decreasing attack rate of subclinical MV infection with increasing levels of specific antibodies until 2.1 IU/mL, above which no subclinical MV infections were detected. The ROC analyses found a correlate of protection of 1.71 IU/mL (95% CI 1.01–2.11) for subclinical MV infection. Our correlates of protection were consistent with previous estimates. This information supports the analyses of serosurveys to detect immunity gaps that require targeted intervention strategies.

Non-transmissible MV Vector with Segmented RNA Genome Establishes Different Types of iPSCs from Hematopoietic Cells

Recent advances in gene therapy technologies have enabled the treatment of congenital disorders and cancers and facilitated the development of innovative methods, including induced pluripotent stem cell (iPSC) production and genome editing. We recently developed a novel non-transmissible and non-integrating measles virus (MV) vector capable of transferring multiple genes simultaneously into a wide range of cells through the CD46 and CD150 receptors. The MV vector expresses four genes for iPSC generation and the GFP gene for a period of time sufficient to establish iPSCs from human fibroblasts as well as peripheral blood T cells. The transgenes were expressed differentially depending on their gene order in the vector. Human hematopoietic stem/progenitor cells were directly and efficiently reprogrammed to naive-like cells that could proliferate and differentiate into primed iPSCs by the same method used to establish primed iPSCs from other cell types. The novel MV vector has several advantages for establishing iPSCs and potential future applications in gene therapy.

Accelerating measles and rubella elimination through research and innovation - Findings from the Measles & Rubella Initiative research prioritization process, 2016

The Measles & Rubella Initiative (M&RI) identified five key strategies to achieve measles and rubella elimination, including research and innovation to support cost-effective operations and improve vaccination and diagnostic tools. In 2016, the M&RI Research and Innovation Working Group (R&IWG) completed a research prioritization process to identify key research questions and update the global research agenda. The R&IWG reviewed meeting reports and strategic planning documents and solicited programmatic inputs from vaccination experts at the program operational level through a web survey, to identify previous research priorities and new research questions. The R&IWG then convened a meeting of experts to prioritize the identified research questions in four strategic areas: (1) epidemiology and economics, (2) surveillance and laboratory, (3) immunization strategies, and (4) demand creation and communications. The experts identified 19 priority research questions in the four strategic areas to address key areas of work necessary to further progress toward elimination. Future commitments from partners will be needed to develop a platform for improved coordination with adequate and predictable resources for research implementation and innovation to address these identified priorities.

Oncolytic Measles Virotherapy and Opposition to Measles Vaccination

Recent measles epidemics in US and European cities where vaccination coverage has declined are providing a harsh reminder for the need to maintain protective levels of immunity across the entire population. Vaccine uptake rates have been declining in large part because of public misinformation regarding a possible association between measles vaccination and autism for which there is no scientific basis. The purpose of this article is to address a new misinformed antivaccination argument-that measles immunity is undesirable because measles virus is protective against cancer. Having worked for many years to develop engineered measles viruses as anticancer therapies, we have concluded (1) that measles is not protective against cancer and (2) that its potential utility as a cancer therapy will be enhanced, not diminished, by prior vaccination.

Evaluating vaccination policies to accelerate measles elimination in China: a meta-population modelling study

BACKGROUND

Measles is among the most highly infectious human diseases. By virtue of increasingly effective childhood vaccination, together with targeted supplemental immunization activities (SIAs), health authorities in the People's Republic of China have reduced measles' reproduction number from about 18 to 2.3. Despite substantial residual susceptibility among young adults, more in some locales than others, sustained routine childhood immunization likely would eliminate measles eventually. To support global eradication efforts, as well as expedite morbidity and mortality reductions in China, we evaluated alternative SIAs via mechanistic mathematical modelling.

METHODS

Our model Chinese population is stratified by immune status (susceptible to measles infection; infected, but not yet infectious; infectious; and recovered or immunized), age (0, 1-4, 5-9, …, 65+ years) and location (31 provinces). Contacts between sub-populations are either empirical or a mixture of preferential and proportionate with respect to age and decline exponentially with distance between locations at age-dependent rates. We estimated initial conditions and most parameters from recent cross-sectional serological surveys, disease surveillance and demographic observations. Then we calculated the reproduction numbers and gradient of the effective number with respect to age- and location-specific immunization rates. We corroborated these analytical results by simulating adolescent and young adult SIAs using a version of our model in which the age-specific contact rates vary seasonally.

RESULTS

Whereas the gradient indicates that vaccinating young adults generally is the optimal strategy, simulations indicate that a catch-up campaign among susceptible adolescent schoolchildren would accelerate elimination, with timing dependent on uptake.

CONCLUSIONS

These results are largely due to indirect effects (i.e. fewer infections than immunized people might otherwise cause), which meta-population models with realistic mixing are uniquely capable of reproducing accurately.

Proficiency Testing of Virus Diagnostics Based on Bioinformatics Analysis of Simulated In Silico High-Throughput Sequencing Data Sets

Quality management and independent assessment of high-throughput sequencing-based virus diagnostics have not yet been established as a mandatory approach for ensuring comparable results. The sensitivity and specificity of viral high-throughput sequence data analysis are highly affected by bioinformatics processing using publicly available and custom tools and databases and thus differ widely between individuals and institutions. Here we present the results of the COMPARE [Collaborative Management Platform for Detection and Analyses of (Re-)emerging and Foodborne Outbreaks in Europe] in silico virus proficiency test. An artificial, simulated in silico data set of Illumina HiSeq sequences was provided to 13 different European institutes for bioinformatics analysis to identify viral pathogens in high-throughput sequence data. Comparison of the participants' analyses shows that the use of different tools, programs, and databases for bioinformatics analyses can impact the correct identification of viral sequences from a simple data set. The identification of slightly mutated and highly divergent virus genomes has been shown to be most challenging. Furthermore, the interpretation of the results, together with a fictitious case report, by the participants showed that in addition to the bioinformatics analysis, the virological evaluation of the results can be important in clinical settings. External quality assessment and proficiency testing should become an important part of validating high-throughput sequencing-based virus diagnostics and could improve the harmonization, comparability, and reproducibility of results. There is a need for the establishment of international proficiency testing, like that established for conventional laboratory tests such as PCR, for bioinformatics pipelines and the interpretation of such results.

Probing Morbillivirus Antisera Neutralization Using Functional Chimerism between Measles Virus and Canine Distemper Virus Envelope Glycoproteins

Measles virus (MeV) is monotypic. Live virus challenge provokes a broadly protective humoral immune response that neutralizes all known measles genotypes. The two surface glycoproteins, H and F, mediate virus attachment and entry, respectively, and neutralizing antibodies to H are considered the main correlate of protection. Herein, we made improvements to the MeV reverse genetics system and generated a panel of recombinant MeVs in which the globular head domain or stalk region of the H glycoprotein or the entire F protein, or both, were substituted with the corresponding protein domains from canine distemper virus (CDV), a closely related morbillivirus that resists neutralization by measles-immune sera. The viruses were tested for sensitivity to human or guinea pig neutralizing anti-MeV antisera and to ferret anti-CDV antisera. Virus neutralization was mediated by antibodies to both H and F proteins, with H being immunodominant in the case of MeV and F being so in the case of CDV. Additionally, the globular head domains of both MeV and CDV H proteins were immunodominant over their stalk regions. These data shed further light on the factors constraining the evolution of new morbillivirus serotypes.

Adult Measles - Case Reports of a Highly Contagious Disease

BACKGROUND

Measles is highly contagious and is caused by the RNA morbillivirus. The best protection is active immunisation in early childhood. Without immunisation morbidity and mortality of measles are high. In recent years, an increasing number of adult measles has been recognised in Europe.

CASE REPORTS

We report here on two adult patients - a 40-year-old male and a 55-year-old female - who presented with fever, fatigue, cough, coryza, conjunctivitis and maculopapular rash. The suspicion of adult measles infection was confirmed by positivity for IgM antibodies against measles virus and reverse-transcriptase polymerase chain reaction in blood and urine. Patients were isolated, and the treatment was symptomatic. In the younger patient, complete recovery was achieved within two weeks. In the older patient, an acute encephalopathy developed after initial improvement characterised by cognitive impairment.

CONCLUSIONS

In patients presenting with fever and maculopapular rash and fatigue, measles should be considered even in adult patients. Early diagnosis with subsequent isolation and registration of patients are important measures to prevent local outbreaks of the disease.

Measles in pregnancy: a threat for Italian women?

Measles in pregnancy may lead to serious sequelae for newborns and mothers. In Italy assessment of immunity against measles is not recommended as pregnancy screening. This study aimed to assess the immunity against measles in pregnant women from Apulia Region in Southern Italy between 2016 and 2017. Overall, 96.9% of pregnant women were positive for anti-measles IgG, younger women aged 19–29 years had a seroprevalence below 90%. No samples were positive for anti-measles IgM. In conclusion, younger pregnant women showed to be at higher risk of contracting measles during pregnancy. These findings have implication for measles vaccination policy and highlight the need for measles antibody testing in pregnancy screening in Italy.

The R2TP complex regulates paramyxovirus RNA synthesis

The regulation of paramyxovirus RNA synthesis by host proteins is poorly understood. Here, we identified a novel regulation mechanism of paramyxovirus RNA synthesis by the Hsp90 co-chaperone R2TP complex. We showed that the R2TP complex interacted with the paramyxovirus polymerase L protein and that silencing of the R2TP complex led to uncontrolled upregulation of mumps virus (MuV) gene transcription but not genome replication. Regulation by the R2TP complex was critical for MuV replication and evasion of host innate immune responses. The R2TP complex also regulated measles virus (MeV) RNA synthesis, but its function was inhibitory and not beneficial to MeV, as MeV evaded host innate immune responses in the absence of the R2TP complex. The identification of the R2TP complex as a critical host factor sheds new light on the regulation of paramyxovirus RNA synthesis.

The family Paramyxoviridae includes several important human and animal pathogens such as mumps virus (MuV) and measles virus (MeV). Paramyxovirus RNA synthesis is strictly regulated by both viral and host proteins. In this study, we identified the R2TP complex as a novel host factor regulating paramyxovirus RNA synthesis. The R2TP complex is a Hsp90 co-chaperone and is involved in Hsp90-mediated assembly of large protein complexes. We showed that the R2TP complex precisely regulated MuV transcription by interacting with the polymerase L protein. This regulation was critical for MuV evasion of host innate immune responses and for viral replication. We also showed that the R2TP complex regulated MeV RNA synthesis, but that its function was inhibitory and not beneficial to MeV. Our findings support a novel regulation mechanism of paramyxovirus RNA synthesis that is directly relevant to its biology and life cycle, and provide the first evidence linking the R2TP complex to defense against viral infection.

Reducing measles mortality in India

A large-scale campaign to promote measles vaccinations has substantially reduced the number of children dying from the disease in India.

Estimating age-specific vaccine effectiveness using data from a large measles outbreak in Berlin, Germany, 2014/15: evidence for waning immunity

BackgroundMeasles elimination is based on 95% coverage with two doses of a measles-containing vaccine (MCV2), high vaccine effectiveness (VE) and life-long vaccine-induced immunity. Longitudinal analysis of antibody titres suggests existence of waning immunity, but the relevance at the population-level is unknown.AimWe sought to assess presence of waning immunity by estimating MCV2 VE in different age groups (2-5, 6-15, 16-23, 24-30 and 31-42 years) in Berlin.MethodsWe conducted a systematic literature review on vaccination coverage and applied the screening-method using data from a large measles outbreak (2014/15) in Berlin. Uncertainty in input variables was incorporated by Monte Carlo simulation. In a scenario analysis, we estimated the proportion vaccinated with MCV2 in those 31-42 years using VE of the youngest age group, where natural immunity was deemed negligible.ResultsOf 773 measles cases (median age: 20 years), 40 had received MCV2. Average vaccine coverage per age group varied (32%-88%). Estimated median VE was  > 99% (95% credible interval (CrI): 98.6-100) in the three youngest age groups, but lower (90.9%, 95% CrI: 74.1-97.6) in the oldest age group. In the scenario analysis, the estimated proportion vaccinated was 98.8% (95% CrI: 96.5-99.8).ConclusionVE for MCV2 was generally high, but lower in those aged 31-42 years old. The estimated proportion with MCV2 should have led to sufficient herd immunity in those aged 31-42 years old. Thus, lower VE cannot be fully explained by natural immunity, suggesting presence of waning immunity.

Molecular characterisation of the emerging measles virus from Roraima state, Brazil, 2018

Measles is a human infectious disease of global concern that is caused by the measles virus. In this study, we report the complete genome sequencing of one measles virus isolate, genotype D8, that was obtained directly from a urine sample in Boa Vista city, the capital of Roraima state in Brazil. Phylogenetic reconstruction grouped the genome described in this study with that of samples from Australia, South Korea, and Italy. To our knowledge, this is the first complete genome sequence of a wild-type measles virus reported from Latin America. Therefore, the present data strengthen the current knowledge on the molecular epidemiology of measles worldwide.

Successes and challenges for preventing measles, mumps and rubella by vaccination

The measles, mumps and rubella (MMR) vaccine has an outstanding safety record and is highly efficacious. High coverage with MMR has led to the elimination of endemic measles, rubella, and congenital rubella syndrome in the US. The biggest challenges to global measles and rubella control and elimination are insufficient vaccination coverage globally and increasing hesitancy. Despite high two dose coverage rates, mumps has made a resurgence in the US and other countries. Mumps outbreaks have occurred primarily in close contact, high-density settings and most cases had received a second dose 10 or more years previously. Waning humoral immunity and antigenic variation of circulating wild-type mumps strains may play a role in the mumps resurgence.

Difficulties in achieving and maintaining the goal of measles elimination in Bulgaria

Measles is a disease with almost a hundred year history of existing registration in Bulgaria and has been subject to mass immunization since 1969. In 2017, after a three-year period with a low number of measles cases registered, an epidemic upsurge has been recorded affecting 3 of the total 28 regions in the country. The purpose of this study was to analyze the changes of measles morbidity in Bulgaria over the period of 1921-2017 and focus on the epidemiological characteristics of the last outbreak in the region of Plovdiv in 2017. For the whole period (1921-2017) the average measles morbidity amounts to 157.69%ооо, decreasing from 525.02%ооо in 1921 to 2.32%ооо in 2017, with 99.5% rate of reduction. In the period prior to vaccination the average morbidity was 247.14%ооо while in the vaccination period it was 70.08%ооо. The ARIMA model could be used as a short-term forecast to predict the morbidity rate. Against the background of the downward tendency in morbidity this study reports a small measles outbreak in Plovdiv, involving 141 cases, after three years of no local virus transmission in the country. An unvaccinated child who returned from abroad probably imported the disease. The measles cases were mainly Roma children and a large number of them were infants. The low intensity and prolong course of the outbreak was indicative of relatively high vaccination coverage of the population. To achieve measles elimination goals, efforts must be made to strengthen surveillance and increase the vaccination coverage, targeting children and especially Roma children.

Cyclical adaptation of measles virus quasispecies to epithelial and lymphocytic cells: To V, or not to V

Measles virus (MeV) is dual-tropic: it replicates first in lymphatic tissues and then in epithelial cells. This switch in tropism raises the question of whether, and how, intra-host evolution occurs. Towards addressing this question, we adapted MeV either to lymphocytic (Granta-519) or epithelial (H358) cells. We also passaged it consecutively in both human cell lines. Since passaged MeV had different replication kinetics, we sought to investigate the underlying genetic mechanisms of growth differences by performing deep-sequencing analyses. Lymphocytic adaptation reproducibly resulted in accumulation of variants mapping within an 11-nucleotide sequence located in the middle of the phosphoprotein (P) gene. This sequence mediates polymerase slippage and addition of a pseudo-templated guanosine to the P mRNA. This form of co-transcriptional RNA editing results in expression of an interferon antagonist, named V, in place of a polymerase co-factor, named P. We show that lymphocytic-adapted MeV indeed produce minimal amounts of edited transcripts and V protein. In contrast, parental and epithelial-adapted MeV produce similar levels of edited and non-edited transcripts, and of V and P proteins. Raji, another lymphocytic cell line, also positively selects V-deficient MeV genomes. On the other hand, in epithelial cells V-competent MeV genomes rapidly out-compete the V-deficient variants. To characterize the mechanisms of genome re-equilibration we rescued four recombinant MeV carrying individual editing site-proximal mutations. Three mutations interfered with RNA editing, resulting in almost exclusive P protein expression. The fourth preserved RNA editing and a standard P-to-V protein expression ratio. However, it altered a histidine involved in Zn²⁺ binding, inactivating V function. Thus, the lymphocytic environment favors replication of V-deficient MeV, while the epithelial environment has the opposite effect, resulting in rapid and thorough cyclical quasispecies re-equilibration. Analogous processes may occur in natural infections with other dual-tropic RNA viruses.

Key questions in infectious disease are how pathogens adapt to different cells of their hosts, and how the interplay between the virus and host factors controls the outcome of infection. Human measles virus (MeV) and related animal morbilliviruses provide important models of pathogenesis because they are dual-tropic: they replicate first in immune cells for spread through the body, and then in epithelial cells for transmission. We sought here to define the underlying molecular and evolutionary processes that allow MeV to spread rapidly in either lymphocytic or epithelial cells. We discovered unexpectedly rapid and thorough genome adaptation to these two tissues. Genome variants that cannot express functional V protein, an innate immunity control protein, are rapidly selected in lymphocytic cells. These variants express only the P protein, a polymerase co-factor, instead of expressing P and V at similar levels. Upon passaging in epithelial cells, V-competent MeV genome variants rapidly re-gain dominance. These results suggest that cyclical quasispecies re-equilibration may occur in acute MeV infections of humans, and that suboptimal variants in one environment constitute a low frequency reservoir for adaptation to the other, where they become dominant.

Determinants of low measles vaccination coverage in children living in an endemic area

Measles outbreaks were recently reported in Europe due to low immunization rates. In this scenario, identifying the reasons of no vaccination is crucial to set up strategies to improve immunization rate. A cross-sectional study was conducted to investigate the determinants of missed vaccination in children living in Southern Italy, during the 2016 outbreak. A standardized face-to-face questionnaire was used to record demographic data, immunization status, and reasons for missed vaccination. A total of 1141 children (median age 86 months, male 47.2%) was enrolled, 77.8% of the children were adequately vaccinated for age, 6.3% were incompletely vaccinated for age, and 15.9% did not receive any vaccine dose. Vaccination rate and reasons for not vaccinating significantly varied according to age, with children ≤ 24 months showing the lowest rate (67.8%). Reasons for not vaccinating included fear for side effects (51%), presence of underlying chronic conditions (12.2%), skip scheduled appointment (12.2%), refusal of vaccination (10.3%), acute illnesses (7.2%), and allergy to eggs (4.6%). The presence of underlying condition was a risk factor for inadequate immunization (p < 0.0001). Only 4.7% of conditions were true contraindications to vaccine administration.Conclusion: We reported inadequate measles immunization rate in Southern Italy, with lowest rates in children ≤ 2 years or with underlying conditions. Only a minority had true contraindications to vaccine uptake. Implementation strategies addressed to health-care professionals and families should focus on the reported determinants to increase measles vaccination coverage. What is Known: • Measles is a viral, highly communicable disease, preventable by vaccine. • Measles elimination in Europe failed as demonstrated by outbreaks in several countries, due to low immunization rates. What is New: • Inadequate measles immunization rate due to false contraindications in Southern Italy, with lowest rates in children ≤ 2 years. • The presence of underlying disease is a risk factor for inadequate immunization.

Structure-based design of a quadrivalent fusion glycoprotein vaccine for human parainfluenza virus types 1-4

Parainfluenza virus types 1-4 (PIV1-4) are highly infectious human pathogens, of which PIV3 is most commonly responsible for severe respiratory illness in newborns, elderly, and immunocompromised individuals. To obtain a vaccine effective against all four PIV types, we engineered mutations in each of the four PIV fusion (F) glycoproteins to stabilize their metastable prefusion states, as such stabilization had previously enabled the elicitation of high-titer neutralizing antibodies against the related respiratory syncytial virus. A cryoelectron microscopy structure of an engineered PIV3 F prefusion-stabilized trimer, bound to the prefusion-specific antibody PIA174, revealed atomic-level details for how introduced mutations improved stability as well as how a single PIA174 antibody recognized the trimeric apex of prefusion PIV3 F. Nine combinations of six newly identified disulfides and two cavity-filling mutations stabilized the prefusion PIV3 F immunogens and induced 200- to 500-fold higher neutralizing titers in mice than were elicited by PIV3 F in the postfusion conformation. For PIV1, PIV2, and PIV4, we also obtained stabilized prefusion Fs, for which prefusion versus postfusion titers were 2- to 20-fold higher. Elicited murine responses were PIV type-specific, with little cross-neutralization of other PIVs. In nonhuman primates (NHPs), quadrivalent immunization with prefusion-stabilized Fs from PIV1-4 consistently induced potent neutralizing responses against all four PIVs. For PIV3, the average elicited NHP titer from the quadrivalent immunization was more than fivefold higher than any titer observed in a cohort of over 100 human adults, highlighting the ability of a prefusion-stabilized immunogen to elicit especially potent neutralization.

Studies into the mechanism of measles-associated immune suppression during a measles outbreak in the Netherlands

Measles causes a transient immune suppression, leading to increased susceptibility to opportunistic infections. In experimentally infected non-human primates (NHPs) measles virus (MV) infects and depletes pre-existing memory lymphocytes, causing immune amnesia. A measles outbreak in the Dutch Orthodox Protestant community provided a unique opportunity to study the pathogenesis of measles immune suppression in unvaccinated children. In peripheral blood mononuclear cells (PBMC) of prodromal measles patients, we detected MV-infected memory CD4⁺ and CD8⁺ T cells and naive and memory B cells at similar levels as those observed in NHPs. In paired PBMC collected before and after measles we found reduced frequencies of circulating memory B cells and increased frequencies of regulatory T cells and transitional B cells after measles. These data support our immune amnesia hypothesis and offer an explanation for the previously observed long-term effects of measles on host resistance. This study emphasises the importance of maintaining high measles vaccination coverage.

The mechanisms by which measles virus infection induces transient immune suppression in humans are poorly understood. Here, Laksono and colleagues characterise the pathogenesis of measles-associated immune suppression in unvaccinated children, and shed new light on the long-term effects of measles on the host.

Impact and longevity of measles-associated immune suppression: a matched cohort study using data from the THIN general practice database in the UK

OBJECTIVE

To test the hypothesis that measles infection increases the incidence of non-measles infectious diseases over a prolonged period of time.

DESIGN

A population-based matched cohort study.

DATA SOURCES

This study examined children aged 1-15 years in The Health Improvement Network UK general practice medical records database. Participants included 2228 patients diagnosed with measles between 1990 and 2014, which were matched on age, sex, general practitioner practice and calendar year with 19 930 children without measles. All controls had received at least one measles vaccination. Children with a history of immune-compromising conditions or with immune-suppressive treatment were excluded.

PRIMARY OUTCOME MEASURES

Incidence rate ratio (IRR) of infections, anti-infective prescriptions and all-cause hospitalisations following measles in predetermined periods using multivariate analysis to adjust for confounding variables.

RESULTS

In children with measles, the incidence rate for non-measles infectious disease was significantly increased in each time period assessed up to 5 years postmeasles: 43% in the first month (IRR: 1.43; 95% CI 1.22 to 1.68), 22% from month one to the first year (IRR: 1.22; 95% CI 1.14 to 1.31), 10% from year 1 to 2.5 years (IRR: 1.10; 95% CI 1.02 to 1.19) and 15% (IRR: 1.15; 95% CI 1.06 to 1.25) in years 2.5 to 5 years of follow-up. Children with measles were more than three times as likely to receive an anti-infective prescription in the first month and 15%-24% more likely between the first month and 5 years. The rate of hospitalisation in children with measles was increased only in the month following diagnosis but not thereafter (IRR: 2.83; 95% CI 1.72 to 4.67).

CONCLUSION

Following measles, children had increased rates of diagnosed infections, requiring increased prescribing of antimicrobial therapies. This population-based matched cohort study supports the hypothesis that measles has a prolonged impact on host resistance to non-measles infectious diseases.

Radiographic and CT Features of Viral Pneumonia

Viruses are the most common causes of respiratory infection. The imaging findings of viral pneumonia are diverse and overlap with those of other nonviral infectious and inflammatory conditions. However, identification of the underlying viral pathogens may not always be easy. There are a number of indicators for identifying viral pathogens on the basis of imaging patterns, which are associated with the pathogenesis of viral infections. Viruses in the same viral family share a similar pathogenesis of pneumonia, and the imaging patterns have distinguishable characteristics. Although not all cases manifest with typical patterns, most typical imaging patterns of viral pneumonia can be classified according to viral families. Although a definite diagnosis cannot be achieved on the basis of imaging features alone, recognition of viral pneumonia patterns may aid in differentiating viral pathogens, thus reducing the use of antibiotics. Recently, new viruses associated with recent outbreaks including human metapneumovirus, severe acute respiratory syndrome coronavirus, and Middle East respiratory syndrome coronavirus have been discovered. The imaging findings of these emerging pathogens have been described in a few recent studies. This review focuses on the radiographic and computed tomographic patterns of viral pneumonia caused by different pathogens, including new pathogens. Clinical characteristics that could affect imaging, such as patient age and immune status, seasonal variation and community outbreaks, and pathogenesis, are also discussed. The first goal of this review is to indicate that there are imaging features that should raise the possibility of viral infections. Second, to help radiologists differentiate viral infections, viruses in the same viridae that have similar pathogenesis and can have similar imaging characteristics are shown. By considering both the clinical and radiologic characteristics, radiologists can suggest the diagnosis of viral pneumonia. ^©RSNA, 2018.

High ratio of measles-specific IgG/IgM associated with nodular pneumonia in vaccinated individuals

BACKGROUND

Vaccinated individuals infected with measles can develop nodular pneumonia. These cases can be misdiagnosed due to the absence of specific IgM and typical symptoms. An effective diagnostic tool is needed.

METHODS

During March 2016, adult inpatients in Yucheng People's Hospital were enrolled prospectively and included in the study. Patients were included if samples were obtained ≤14 days from the onset of fever. Measles virus was detected by RT-PCR of the oropharyngeal swab sample. Chest computed tomography scans and medical records were obtained. Oropharyngeal swabs and blood samples were collected for IgM and IgG testing, RT-PCR, and gene sequencing.

RESULTS

Sixteen patients were enrolled. Ten were found to have nodular pneumonia and were defined as the nodular group. The remaining six patients were defined as the control group. Measles-specific IgG titers in the nodular group were high (3618.3-5000mIU/ml), while IgM titers were low (<25mIU/ml); IgG titers in the control group were low (241.4-2560.3mIU/ml), while IgM titers were high (137-5000mIU/ml). No obvious viral mutation was detected in the nodular group.

CONCLUSIONS

Measles-associated nodular pneumonia was only evident in those patients with an IgG/IgM ratio >20. In measles outbreaks, the IgG/IgM ratio may be useful to identify nodular pneumonia.

Use of a Diagonal Approach to Health System Strengthening and Measles Elimination after a Large Nationwide Outbreak in Mongolia

Measles is a highly transmissible infectious disease that causes serious illness and death worldwide. Efforts to eliminate measles through achieving high immunization coverage, well-performing surveillance systems, and rapid and effective outbreak response mechanisms while strategically engaging and strengthening health systems have been termed a diagonal approach. In March 2015, a large nationwide measles epidemic occurred in Mongolia, 1 year after verification of measles elimination in this country. A multidisciplinary team conducted an outbreak investigation that included a broad health system assessment, organized around the Global Health Security Agenda framework of Prevent-Detect-Respond, to provide recommendations for evidence-based interventions to interrupt the epidemic and strengthen the overall health system to prevent future outbreaks of measles and other epidemic-prone infectious threats. This investigation demonstrated the value of evaluating elements of the broader health system in investigating measles outbreaks and the need for using a diagonal approach to achieving sustainable measles elimination.

Oncolytic Viruses for Multiple Myeloma Therapy

Although recent treatment advances have improved outcomes for patients with multiple myeloma (MM), the disease frequently becomes refractory to current therapies. MM thus remains incurable for most patients and new therapies are urgently needed. Oncolytic viruses are a promising new class of therapeutics that provide tumor-targeted therapy by specifically infecting and replicating within cancerous cells. Oncolytic therapy yields results from both direct killing of malignant cells and induction of an anti-tumor immune response. In this review, we will describe oncolytic viruses that are being tested for MM therapy with a focus on those agents that have advanced into clinical trials.

A Microneedle Patch for Measles and Rubella Vaccination Is Immunogenic and Protective in Infant Rhesus Macaques

Background

New methods to increase measles and rubella (MR) vaccination coverage are needed to achieve global and regional MR elimination goals.

Methods

Here, we developed microneedle (MN) patches designed to administer MR vaccine by minimally trained personnel, leave no biohazardous sharps waste, remove the need for vaccine reconstitution, and provide thermostability outside the cold chain. This study evaluated the immunogenicity of MN patches delivering MR vaccine to infant rhesus macaques.

Results

Protective titers of measles neutralizing antibodies (>120 mIU/mL) were detected in 100% of macaques in the MN group and 75% of macaques in the subcutaneous (SC) injection group. Rubella neutralizing antibody titers were >10 IU/mL for all groups. All macaques in the MN group were protected from challenge with wild-type measles virus, whereas 75% were protected in the SC group. However, vaccination by the MN or SC route was unable to generate protective immune responses to measles in infant macaques pretreated with measles immunoglobulin to simulate maternal antibody.

Conclusions

These results show, for the first time, that MR vaccine delivered by MN patch generated protective titers of neutralizing antibodies to both measles and rubella in infant rhesus macaques and afforded complete protection from measles virus challenge.

In Vitro Measles Virus Infection of Human Lymphocyte Subsets Demonstrates High Susceptibility and Permissiveness of both Naive and Memory B Cells

Measles is characterized by a transient immune suppression, leading to an increased risk of opportunistic infections. Measles virus (MV) infection of immune cells is mediated by the cellular receptor CD150, expressed by subsets of lymphocytes, dendritic cells, macrophages, and thymocytes. Previous studies showed that human and nonhuman primate memory T cells express higher levels of CD150 than naive cells and are more susceptible to MV infection. However, limited information is available about the CD150 expression and relative susceptibility to MV infection of B-cell subsets. In this study, we assessed the susceptibility and permissiveness of naive and memory T- and B-cell subsets from human peripheral blood or tonsils to in vitro MV infection. Our study demonstrates that naive and memory B cells express CD150, but at lower frequencies than memory T cells. Nevertheless, both naive and memory B cells proved to be highly permissive to MV infection. Furthermore, we assessed the susceptibility and permissiveness of various functionally distinct T and B cells, such as helper T (TH) cell subsets and IgG- and IgA-positive memory B cells, in peripheral blood and tonsils. We demonstrated that TH1TH17 cells and plasma and germinal center B cells were the subsets most susceptible and permissive to MV infection. Our study suggests that both naive and memory B cells, along with several other antigen-experienced lymphocytes, are important target cells of MV infection. Depletion of these cells potentially contributes to the pathogenesis of measles immune suppression.IMPORTANCE Measles is associated with immune suppression and is often complicated by bacterial pneumonia, otitis media, or gastroenteritis. Measles virus infects antigen-presenting cells and T and B cells, and depletion of these cells may contribute to lymphopenia and immune suppression. Measles has been associated with follicular exhaustion in lymphoid tissues in humans and nonhuman primates, emphasizing the importance of MV infection of B cells in vivo However, information on the relative susceptibility of B-cell subsets is scarce. Here, we compared the susceptibility and permissiveness to in vitro MV infection of human naive and memory T- and B-cell subsets isolated from peripheral blood or tonsils. Our results demonstrate that both naive and memory B cells are more permissive to MV infection than T cells. The highest infection levels were detected in plasma cells and germinal center B cells, suggesting that infection and depletion of these populations contribute to reduced host resistance.

Complete Genome Sequences of Six Measles Virus Strains

Genetic characterization of wild-type measles virus (MV) strains is a critical component of measles surveillance and molecular epidemiology. We have obtained complete genome sequences of six MV strains belonging to different genotypes, using random-primed next generation sequencing.

Molecular characterisation of measles virus strains among refugees from Central African Republic in Cameroon in 2014

Measles is a highly infectious human viral disease caused by measles virus (MeV). An estimated 114 900 measles deaths occurred worldwide in 2014. There are currently eight clades (A-H) comprised 24 MeV genotypes. We sought to characterise MeVs among Central African Republic (CAR) refugees during the 2014 measles epidemic in Cameroon. Samples were collected from children <15 years with suspected measles infections in two refugee camps in the east region of Cameroon. Viral RNA was extracted directly from urine samples. RNA detection of MeV RNA was performed with real-time reverse transcription polymerase chain reaction (PCR) to amplify a 634 bp nucleotide fragment of the N gene. The sequence of the PCR product was obtained to determine the genotype. MeV RNA was detected in 25 out of 30 samples from suspected cases, and among the 25 positive samples, MeV sequences were obtained from 20. The MeV strains characterised were all genotype B3. The MeV strains from genotype B3 found in this outbreak were more similar to those circulating in Northern Cameroon in 2010-2011 than to MeV strains circulating in the CAR in 2011. Surveillance system should be improved to focus on refugees for early detection of and response to outbreaks.

Measles and rubella elimination: learning from polio eradication and moving forward with a diagonal approach

INTRODUCTION

In 1988, an estimated 350,000 children were paralyzed by polio and 125 countries reported polio cases, the World Health Assembly passed a resolution to achieve polio eradication by 2000, and the Global Polio Eradication Initiative (GPEI) was established as a partnership focused on eradication. Today, following eradication efforts, polio cases have decreased >99% and eradication of all three types of wild polioviruses is approaching. However, since polio resources substantially support disease surveillance and other health programs, losing polio assets could reverse progress toward achieving Global Vaccine Action Plan goals. Areas covered: As the end of polio approaches and GPEI funds and capacity decrease, we document knowledge, experience, and lessons learned from 30 years of polio eradication. Expert commentary: Transitioning polio assets to measles and rubella (MR) elimination efforts would accelerate progress toward global vaccination coverage and equity. MR elimination feasibility and benefits have long been established. Focusing efforts on MR elimination after achieving polio eradication would make a permanent impact on reducing child mortality but should be done through a 'diagonal approach' of using measles disease transmission to identify areas possibly susceptible to other vaccine-preventable diseases and to strengthen the overall immunization and health systems to achieve disease-specific goals.

Needle-free delivery of measles virus vaccine to the lower respiratory tract of non-human primates elicits optimal immunity and protection

Needle-free measles virus vaccination by aerosol inhalation has many potential benefits. The current standard route of vaccination is subcutaneous injection, whereas measles virus is an airborne pathogen. However, the target cells that support replication of live-attenuated measles virus vaccines in the respiratory tract are largely unknown. The aims of this study were to assess the in vivo tropism of live-attenuated measles virus and determine whether respiratory measles virus vaccination should target the upper or lower respiratory tract. Four groups of twelve cynomolgus macaques were immunized with 10⁴ TCID₅₀ of recombinant measles virus vaccine strain Edmonston-Zagreb expressing enhanced green fluorescent protein. The vaccine virus was grown in MRC-5 cells and formulated with identical stabilizers and excipients as used in the commercial MV^EZ vaccine produced by the Serum Institute of India. Animals were immunized by hypodermic injection, intra-tracheal inoculation, intra-nasal instillation, or aerosol inhalation. In each group six animals were euthanized at early time points post-vaccination, whereas the other six were followed for 14 months to assess immunogenicity and protection from challenge infection with wild-type measles virus. At early time-points, enhanced green fluorescent protein-positive measles virus-infected cells were detected locally in the muscle, nasal tissues, lungs, and draining lymph nodes. Systemic vaccine virus replication and viremia were virtually absent. Infected macrophages, dendritic cells and tissue-resident lymphocytes predominated. Exclusive delivery of vaccine virus to the lower respiratory tract resulted in highest immunogenicity and protection. This study sheds light on the tropism of a live-attenuated measles virus vaccine and identifies the alveolar spaces as the optimal site for respiratory delivery of measles virus vaccine.

Vaccine platform recombinant measles virus

The classic development of vaccines is lengthy, tedious, and may not necessarily be successful as demonstrated by the case of HIV. This is especially a problem for emerging pathogens that are newly introduced into the human population and carry the inherent risk of pandemic spread in a naïve population. For such situations, a considerable number of different platform technologies are under development. These are also under development for pathogens, where directly derived vaccines are regarded as too complicated or even dangerous due to the induction of inefficient or unwanted immune responses causing considerable side-effects as for dengue virus. Among platform technologies are plasmid-based DNA vaccines, RNA replicons, single-round infectious vector particles, or replicating vaccine-based vectors encoding (a) critical antigen(s) of the target pathogens. Among the latter, recombinant measles viruses derived from vaccine strains have been tested. Measles vaccines are among the most effective and safest life-attenuated vaccines known. Therefore, the development of Schwarz-, Moraten-, or AIK-C-strain derived recombinant vaccines against a wide range of mostly viral, but also bacterial pathogens was quite straightforward. These vaccines generally induce powerful humoral and cellular immune responses in appropriate animal models, i.e., transgenic mice or non-human primates. Also in the recent first clinical phase I trial, the results have been quite encouraging. The trial indicated the expected safety and efficacy also in human patients, interestingly independent from the level of prevalent anti-measles immunity before the trial. Thereby, recombinant measles vaccines expressing additional antigens are a promising platform for future vaccines.

Transitioning Lessons Learned and Assets of the Global Polio Eradication Initiative to Global and Regional Measles and Rubella Elimination

The Global Polio Eradication Initiative has built an extensive infrastructure with capabilities and resources that should be transitioned to measles and rubella elimination efforts. Measles continues to be a major cause of child mortality globally, and rubella continues to be the leading infectious cause of birth defects. Measles and rubella eradication is feasible and cost saving. The obvious similarities in strategies between polio elimination and measles and rubella elimination include the use of an extensive surveillance and laboratory network, outbreak preparedness and response, extensive communications and social mobilization networks, and the need for periodic supplementary immunization activities. Polio staff and resources are already connected with those of measles and rubella, and transitioning existing capabilities to measles and rubella elimination efforts allows for optimized use of resources and the best opportunity to incorporate important lessons learned from polio eradication, and polio resources are concentrated in the countries with the highest burden of measles and rubella. Measles and rubella elimination strategies rely heavily on achieving and maintaining high vaccination coverage through the routine immunization activity infrastructure, thus creating synergies with immunization systems approaches, in what is termed a "diagonal approach."

Challenges to global measles eradication: is it all in the timing?

The case for global eradication of measles was first made in 1982. Since then, technical aspects of measles eradication have concluded that measles satisfied all criteria required for eradication. To date, only smallpox, among human diseases, has been eradicated, with polio, the next eradication candidate. In all previous eradication programmes, the pattern of slow implementation and missed deadlines is similar. Lessons from these past eradication programs should inform development of a time-limited measles eradication program. Notably, no measles eradication resolution is likely until member states are satisfied that polio eradication is accomplished. However, there is an impetus for measles eradication from the western hemisphere, where governments continue to pay the high costs of keeping their region measles free until global measles eradication is achieved. While previous vaccine preventable diseases eradications have depended on supplemental immunizations (SIAs), measles eradication will have to build both on SIAs and routine immunization systems strengthening. This article reviews non-technical considerations that could facilitate the delivery of a time-limited measles eradication initiative. The issues discussed are categorized as a) specificities of measles disease; b) specifics of measles vaccine/vaccination; c) special considerations for endemic countries and d) organization of international partnerships. The disease and vaccine specific issues are not insurmountable. The introduction of routine measles second dose, in the context of EPI systems strengthening, is paramount to endemic developing countries. In the international partnerships, it should be noted that i) Measles eradication will be easier and cheaper; ii) the return on investment is compelling; iii) leverage is feasible on the experiences of the Measles/Rubella initiative; iv) two disease eradication targets in one initiative are feasible and v) for the first time, an eradication investment case will inform the decisions. However, if previous eradication efforts have been marathons, measles eradication will need to be a sprint.

Delineating morbillivirus entry, dissemination and airborne transmission by studying in vivo competition of multicolor canine distemper viruses in ferrets

Identification of cellular receptors and characterization of viral tropism in animal models have vastly improved our understanding of morbillivirus pathogenesis. However, specific aspects of viral entry, dissemination and transmission remain difficult to recapitulate in animal models. Here, we used three virologically identical but phenotypically distinct recombinant (r) canine distemper viruses (CDV) expressing different fluorescent reporter proteins for in vivo competition and airborne transmission studies in ferrets (Mustela putorius furo). Six donor ferrets simultaneously received three rCDVs expressing green, red or blue fluorescent proteins via conjunctival (ocular, Oc), intra-nasal (IN) or intra-tracheal (IT) inoculation. Two days post-inoculation sentinel ferrets were placed in physically separated adjacent cages to assess airborne transmission. All donor ferrets developed lymphopenia, fever and lethargy, showed progressively increasing systemic viral loads and were euthanized 14 to 16 days post-inoculation. Systemic replication of virus inoculated via the Oc, IN and IT routes was detected in 2/6, 5/6 and 6/6 ferrets, respectively. In five donor ferrets the IT delivered virus dominated, although replication of two or three different viruses was detected in 5/6 animals. Single lymphocytes expressing multiple fluorescent proteins were abundant in peripheral blood and lymphoid tissues, demonstrating the occurrence of double and triple virus infections. Transmission occurred efficiently and all recipient ferrets showed evidence of infection between 18 and 22 days post-inoculation of the donor ferrets. In all cases, airborne transmission resulted in replication of a single-colored virus, which was the dominant virus in the donor ferret. This study demonstrates that morbilliviruses can use multiple entry routes in parallel, and co-infection of cells during viral dissemination in the host is common. Airborne transmission was efficient, although transmission of viruses expressing a single color suggested a bottleneck event. The identity of the transmitted virus was not determined by the site of inoculation but by the viral dominance during dissemination.

Challenges of measles and rubella laboratory diagnostic in the era of elimination

The Member States of the WHO European Region adopted the goal of measles and rubella elimination more than 10 years ago, but so far only 21 of 53 countries have reached this target. Laboratory investigation of suspected cases is essential to support disease elimination efforts. Therefore, WHO maintains a network of accredited laboratories providing high-quality testing. Laboratory investigation heavily relies on specific IgM serology and increasingly on virus detection by reverse transcription (RT)-PCR, but other methods such as IgG avidity testing and genetic characterization of virus strains have gained in importance. In elimination settings, often few samples from suspected cases are available for testing, but testing proficiency must be maintained. The predictive value of an IgM-positive result decreases and other rash-fever disease aetiologies become more important. In addition, cases with a rash after measles/rubella vaccination or with mild disease after waning of vaccine-induced antibodies are seen more often. Thus, it is necessary to perform comprehensive and potentially time-consuming and costly investigations of every suspected case using quality-controlled laboratory methods. At the same time rapid feedback to public health officers is required for timely interventions. The introduction of new laboratory methods for comprehensive case investigations requires training of staff under the supervision of WHO-accredited reference laboratories and the definition of appropriate test algorithms. Clinical, laboratory, and epidemiological data are essential for final case classification and investigation of chains of transmission in the endgame of measles and rubella elimination.

Perspective on Global Measles Epidemiology and Control and the Role of Novel Vaccination Strategies

Measles is a highly contagious, vaccine preventable disease. Measles results in a systemic illness which causes profound immunosuppression often leading to severe complications. In 2010, the World Health Assembly declared that measles can and should be eradicated. Measles has been eliminated in the Region of the Americas, and the remaining five regions of the World Health Organization (WHO) have adopted measles elimination goals. Significant progress has been made through increased global coverage of first and second doses of measles-containing vaccine, leading to a decrease in global incidence of measles, and through improved case based surveillance supported by the WHO Global Measles and Rubella Laboratory Network. Improved vaccine delivery methods will likely play an important role in achieving measles elimination goals as these delivery methods circumvent many of the logistic issues associated with subcutaneous injection. This review highlights the status of global measles epidemiology, novel measles vaccination strategies, and describes the pathway toward measles elimination.

Progress towards Rapid Detection of Measles Vaccine Strains: a Tool To Inform Public Health Interventions

Rapid differentiation of vaccine from wild-type strains in suspect measles cases is a valuable epidemiological tool that informs the public health response to this highly infectious disease. Few public health laboratories sequence measles virus-positive specimens to determine genotype, and the vaccine-specific real-time reverse transcriptase PCR (rRT-PCR) assay described by F. Roy et al. (J. Clin. Microbiol. 55:735-743, 2017, https://doi.org/10.1128/JCM.01879-16) offers a rapid, easily adoptable method to identify measles vaccine strains in suspect cases.

Viral-bacterial co-infections in the respiratory tract

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Viruses predispose to secondary bacterial infection throughout the respiratory tract.

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Viral damage to airway epithelium and aberrant inflammatory responses play key roles.

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Dysregulation of both innate and acquired immune effectors contribute to co-infection.

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Viral co-infection promotes bacterial invasion of sterile sites within the airway.

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Optimal treatment likely requires control of both bacterial growth and host responses.

Preceding or concurrent viral respiratory tract infection can predispose to secondary bacterial co-infection throughout the airway. The mechanisms by which viruses promote these superinfections are diverse and replete. Whereas we understand much as to how viruses damage the airway and dysregulate both innate and acquired immune responses which, in turn, supports bacterial growth, adherence and invasion into normally sterile sites within the respiratory tract, new information regarding these co-infections is being gained from recent advances in microbiome research and our enhanced appreciation of the contribution of bacterial biofilms, among others. The advanced understanding obtained by continued research efforts in all aspects of viral–bacterial co-infections of the respiratory tract will allow us to devise novel approaches for disease prevention as well as to develop more effective therapeutics.

Morbillivirus Experimental Animal Models: Measles Virus Pathogenesis Insights from Canine Distemper Virus

Morbilliviruses share considerable structural and functional similarities. Even though disease severity varies among the respective host species, the underlying pathogenesis and the clinical signs are comparable. Thus, insights gained with one morbillivirus often apply to the other members of the genus. Since the Canine distemper virus (CDV) causes severe and often lethal disease in dogs and ferrets, it is an attractive model to characterize morbillivirus pathogenesis mechanisms and to evaluate the efficacy of new prophylactic and therapeutic approaches. This review compares the cellular tropism, pathogenesis, mechanisms of persistence and immunosuppression of the Measles virus (MeV) and CDV. It then summarizes the contributions made by studies on the CDV in dogs and ferrets to our understanding of MeV pathogenesis and to vaccine and drugs development.

Improving the Science of Measles Prevention-Will It Make for a Better Immunization Program?

In a Perspective, Julie Garon and Walter Orenstein discuss Lessler and colleagues' modeling study on measles vaccination and the implications for triggered and routine immunization programs.