Rational attenuation of canine distemper virus (CDV) to develop a morbillivirus animal model that mimics measles in humans

Morbilliviruses are members of the family Paramyxoviridae and are known for their ability to cause systemic disease in a variety of mammalian hosts. The prototypic morbillivirus, measles virus (MeV), infects humans and still causes morbidity and mortality in unvaccinated children and young adults. Experimental infection studies in non-human primates have contributed to the understanding of measles pathogenesis. However, ethical restrictions call for the development of new animal models. Canine distemper virus (CDV) infects a wide range of animals, including ferrets, and its pathogenesis shares many features with measles. However, wild-type CDV infection is almost always lethal, while MeV infection is usually self-limiting. Here, we made five recombinant CDVs, predicted to be attenuated, and compared their pathogenesis to the non-attenuated recombinant CDV in a ferret model. Three viruses were insufficiently attenuated based on clinical signs, fatality, and systemic infection, while one virus was too attenuated. The last candidate virus caused a self-limiting infection associated with transient viremia and viral dissemination to all lymphoid tissues, was shed transiently from the upper respiratory tract, and did not result in acute neurological signs. Additionally, an in-depth phenotyping of the infected white blood cells showed lower infection percentages in all lymphocyte subsets when compared to the non-attenuated CDV. In conclusion, infection models using this candidate virus mimic measles and can be used to study pathogenesis-related questions and to test interventions for morbilliviruses in a natural host species.IMPORTANCEMorbilliviruses are transmitted via the respiratory route but cause systemic disease. The viruses use two cellular receptors to infect myeloid, lymphoid, and epithelial cells. Measles virus (MeV) remains an important cause of morbidity and mortality in humans, requiring animal models to study pathogenesis or intervention strategies. Experimental MeV infections in non-human primates are restricted by ethical and practical constraints, and animal morbillivirus infections in natural host species have been considered as alternatives. Inoculation of ferrets with wild-type canine distemper virus (CDV) has been used for this purpose, but in most cases, the virus overwhelms the immune system and causes highly lethal disease. Introduction of an additional transcription unit and an additional attenuating point mutation in the polymerase yielded a candidate virus that caused self-limiting disease with transient viremia and virus shedding. This rationally attenuated CDV strain can be used for experimental morbillivirus infections in ferrets that reflect measles in humans.

The Reemergence of Measles

OBJECTIVES

Present-day pathologists may be unfamiliar with the histopathologic features of measles, which is a reemerging disease. Awareness of these features may enable early diagnosis of measles in unsuspected cases, including those with an atypical presentation. Using archived tissue samples from historic patients, a unique source of histopathologic information about measles and other reemerging infectious diseases, we performed a comprehensive analysis of the histopathologic features of measles seen in commonly infected tissues during prodrome, active, and late phases of the disease.

METHODS

Subspecialty pathologists analyzed H&E-stained slides of specimens from 89 patients accessioned from 1919 to 1998 and correlated the histopathologic findings with clinical data.

RESULTS

Measles caused acute and chronic histopathologic changes, especially in the respiratory, lymphoid (including appendix and tonsils), and central nervous systems. Bacterial infections in lung and other organs contributed significantly to adverse outcomes, especially in immunocompromised patients.

CONCLUSIONS

Certain histopathologic features, especially Warthin-Finkeldey cells and multinucleated giant cells without inclusions, allow pathologists to diagnose or suggest the diagnosis of measles in unsuspected cases.

Inpatient morbidity and mortality of measles in the United States

Background

Measles is an extremely contagious, vaccine-preventable infection that was officially declared eradicated in the US in 2000. However, measles outbreaks are increasingly occurring in the US. Measles cases have considerable morbidity requiring hospitalization, yet little is known about hospitalization and complications from measles in recent years.

Objectives

To analyze the frequency, predictors, costs and other outcomes of hospitalization for measles in the US.

Methods

The 2002–2016 Nationwide Inpatient Sample, containing a 20% sample of US hospitalizations (n = 96,568,625), was analyzed. Measles and comorbidities were defined by International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) or ICD-10-CM codes. Multivariable survey logistic regression and linear regression models controlling for sociodemographic demographic factors were constructed to understand associations with organ-specific complications, and cost of care and length of stay, respectively.

Results

Overall, 1,018 measles hospitalizations occurred in 2002–2016, and hospitalizations increased over time. In multivariable logistic regression models, measles was associated with higher odds of gastrointestinal, hematologic, infectious, neurologic, ophthalmologic, pulmonary, and renal complications, with the strongest association observed with encephalitis (39.84 [16.51–96.12], P<0.0001). Increased length of stay (LOS) and similar cost of care (mean [95% CI]; 4.8 [4.4–5.4]; $7,438 [$6,446-$8,582]) were observed versus (vs.) all other admissions (4.5 [4.4–4.5]; P<0.01; $7,854 [$7,774-$7,935], P>0.05). There were 34 deaths in hospitalized measles patients; inpatient mortality was numerically higher in those with vs. without measles (proportion ± SEM: 3.3±1.2% vs. 2.3±0.01%, P = 0.333).

Limitations

Lack of outpatient or prescription data.

Conclusions

Measles continues to pose a substantial and preventable health care burden, with serious complications, hospitalization and inpatient mortality. Further studies are needed to improve the prevention and management of measles.

Effect of vaccination on severity and infectiousness of measles during an outbreak in the Netherlands, 2013-2014

An outbreak of measles in the Netherlands in 2013-2014 provided an opportunity to assess the effect of MMR vaccination on severity and infectiousness of measles.Measles is notifiable in the Netherlands. We used information on vaccination, hospitalisation, complications, and most likely source(s) of infection from cases notified during the outbreak. When a case was indicated as a likely source for at least one other notified case, we defined it as infectious. We estimated the age-adjusted effect of vaccination on severity and infectiousness with logistic regression.Of 2676 notified cases, 2539 (94.9%) were unvaccinated, 121 (4.5%) were once-vaccinated and 16 (0.6%) were at least twice-vaccinated; 328 (12.3%) cases were reported to have complications and 172 (6.4%) cases were hospitalised. Measles in twice-vaccinated cases led less often to complications and/or hospitalisation than measles in unvaccinated cases (0% and 14.5%, respectively, aOR 0.1 (95% CI 0-0.89), P = 0.03). Of unvaccinated, once-vaccinated and twice-vaccinated cases, respectively, 194 (7.6%), seven (5.1%) and 0 (0%) were infectious. These differences were not statistically significant (P > 0.05).Our findings suggest a protective effect of vaccination on the occurrence of complications and/or hospitalisation as a result of measles and support the WHO recommendation of a two-dose MMR vaccination schedule.

Family Health Days program contributions in vaccination of unreached and under-immunized children during routine vaccinations in Uganda

Background

We explored the contributions of the Family Health Days (FHDs) concept, which was developed by the Uganda Ministry of Health (MOH) and UNICEF as a supplementary quarterly outreach program in addition to strengthening the routine expanded program for immunization (EPI), with the aim to increase coverage, through improved access to the unimmunized or unreached and under-immunized children under 5 years.

Method

A cross-sectional descriptive study of the Uganda MOH, Health Management Information Systems (HMIS) and UNICEF in house FHDs data was conducted covering six quarterly implementations of the program between April 2012 and December 2013. The FHDs program was implemented in 31 priority districts with low routine vaccination coverage from seven sub-regions in Uganda in a phased manner using places of worship for service delivery.

Results

During the six rounds of FHDs in the 31 districts, a total of 178,709 and 191,223 children received measles and Diphtheria-Pertussis-Tetanus (DPT3) vaccinations, respectively. The FHDs’ contributions were 126% and 144% for measles and 103% and 122% for DPT3 in 2012 and 2013, respectively of the estimated unreached annual target populations. All implementing sub-regions after two rounds in 2012 attained over and above the desired target for DPT3 (85%) and measles (90%). The same was true in 2013 after four rounds, except for Karamoja and West Nile sub-regions, where in some districts a substantial proportion of children remained unimmunized. The administrative data for both DPT3 and measles immunization showed prominent and noticeable increase in coverage trend in FHDS regions for the months when the program was implemented.

Conclusion

The FHDs program improved vaccination equity by reaching the unreached and hard-to-reach children and bridging the gap in immunization coverage, and fast tracking the achievement of targets recommended by the Global Vaccine Action Plan (GVAP) for measles and DPT3 (85% and 90% respectively) in implementing sub-regions and districts. The FHDs is an innovative program to supplement routine immunizations designed to reach the unreached and under immunized children.

Measles Encephalitis: Towards New Therapeutics

Measles remains a major cause of morbidity and mortality worldwide among vaccine preventable diseases. Recent decline in vaccination coverage resulted in re-emergence of measles outbreaks. Measles virus (MeV) infection causes an acute systemic disease, associated in certain cases with central nervous system (CNS) infection leading to lethal neurological disease. Early following MeV infection some patients develop acute post-infectious measles encephalitis (APME), which is not associated with direct infection of the brain. MeV can also infect the CNS and cause sub-acute sclerosing panencephalitis (SSPE) in immunocompetent people or measles inclusion-body encephalitis (MIBE) in immunocompromised patients. To date, cellular and molecular mechanisms governing CNS invasion are still poorly understood. Moreover, the known MeV entry receptors are not expressed in the CNS and how MeV enters and spreads in the brain is not fully understood. Different antiviral treatments have been tested and validated in vitro, ex vivo and in vivo, mainly in small animal models. Most treatments have high efficacy at preventing infection but their effectiveness after CNS manifestations remains to be evaluated. This review describes MeV neural infection and current most advanced therapeutic approaches potentially applicable to treat MeV CNS infection.

Type I Interferon Receptor Signaling Drives Selective Permissiveness of Astrocytes and Microglia to Measles Virus during Brain Infection

Fatal neurological syndromes can occur after measles virus (MeV) infection of the brain. The mechanisms controlling MeV spread within the central nervous system (CNS) remain poorly understood. We analyzed the role of type I interferon (IFN-I) receptor (IFNAR) signaling in the control of MeV infection in a murine model of brain infection. Using organotypic brain cultures (OBC) from wild-type and IFNAR-knockout (IFNARKO) transgenic mice ubiquitously expressing the human SLAM (CD150) receptor, the heterogeneity of the permissiveness of different CNS cell types to MeV infection was characterized. In the absence of IFNAR signaling, MeV propagated significantly better in explant slices. In OBC from IFNAR-competent mice, while astrocytes and microglia were infected on the day of explant preparation, they became refractory to infection with time, in contrast to neurons and oligodendrocytes, which remained permissive to infection. This selective loss of permissiveness to MeV infection was not observed in IFNARKO mouse OBC. Accordingly, the development of astrogliosis related to the OBC procedure was exacerbated in the presence of IFNAR signaling. In the hippocampus, this astrogliosis was characterized by a change in the astrocyte phenotype and by an increase of IFN-I transcripts. A proteome analysis showed the upregulation of 84 out of 111 secreted proteins. In the absence of IFNAR, only 27 secreted proteins were upregulated, and none of these were associated with antiviral activities. Our results highlight the essential role of the IFN-I response in astrogliosis and in the permissiveness of astrocytes and microglia that could control MeV propagation throughout the CNS.IMPORTANCE Measles virus (MeV) can infect the central nervous system (CNS), with dramatic consequences. The mechanisms controlling MeV invasion of the CNS remain ill-defined since most previous data were obtained from postmortem analysis. Here, we highlight for the first time the crucial role of the type I interferon (IFN-I) response not only in the control of CNS invasion but also in the early permissiveness of glial cells to measles virus infection.

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.

Cell-to-Cell Measles Virus Spread between Human Neurons Is Dependent on Hemagglutinin and Hyperfusogenic Fusion Protein

Measles virus (MV) usually causes acute infection but in rare cases persists in the brain, resulting in subacute sclerosing panencephalitis (SSPE). Since human neurons, an important target affected in the disease, do not express the known MV receptors (signaling lymphocyte activation molecule [SLAM] and nectin 4), how MV infects neurons and spreads between them is unknown. Recent studies have shown that many virus strains isolated from SSPE patients possess substitutions in the extracellular domain of the fusion (F) protein which confer enhanced fusion activity. Hyperfusogenic viruses with such mutations, unlike the wild-type MV, can induce cell-cell fusion even in SLAM- and nectin 4-negative cells and spread efficiently in human primary neurons and the brains of animal models. We show here that a hyperfusogenic mutant MV, IC323-F(T461I)-EGFP (IC323 with a fusion-enhancing T461I substitution in the F protein and expressing enhanced green fluorescent protein), but not the wild-type MV, spreads in differentiated NT2 cells, a widely used human neuron model. Confocal time-lapse imaging revealed the cell-to-cell spread of IC323-F(T461I)-EGFP between NT2 neurons without syncytium formation. The production of virus particles was strongly suppressed in NT2 neurons, also supporting cell-to-cell viral transmission. The spread of IC323-F(T461I)-EGFP was inhibited by a fusion inhibitor peptide as well as by some but not all of the anti-hemagglutinin antibodies which neutralize SLAM- or nectin-4-dependent MV infection, suggesting the presence of a distinct neuronal receptor. Our results indicate that MV spreads in a cell-to-cell manner between human neurons without causing syncytium formation and that the spread is dependent on the hyperfusogenic F protein, the hemagglutinin, and the putative neuronal receptor for MV.IMPORTANCE Measles virus (MV), in rare cases, persists in the human central nervous system (CNS) and causes subacute sclerosing panencephalitis (SSPE) several years after acute infection. This neurological complication is almost always fatal, and there is currently no effective treatment for it. Mechanisms by which MV invades the CNS and causes the disease remain to be elucidated. We have previously shown that fusion-enhancing substitutions in the fusion protein of MVs isolated from SSPE patients contribute to MV spread in neurons. In this study, we demonstrate that MV bearing the hyperfusogenic mutant fusion protein spreads between human neurons in a cell-to-cell manner. Spread of the virus was inhibited by a fusion inhibitor peptide and antibodies against the MV hemagglutinin, indicating that both the hemagglutinin and hyperfusogenic fusion protein play important roles in MV spread between human neurons. The findings help us better understand the disease process of SSPE.

An Outbreak of Measles in a University in Korea, 2014

Measles has been declared eliminated from the Korea since 2006. In April 2014, a measles outbreak occurred at a University in Seoul. A total of 85 measles cases were identified. In order to estimate vaccine effectiveness of measles vaccine, we reviewed the vaccination records of the university students. The vaccine effectiveness of two doses of measles containing vaccine was 60.0% (95% CI, 38.2-74.1; P < 0.05). Transmission was interrupted after the introduction of outbreak-response immunization. The outbreak shows that pockets of under-immunity among college students may have facilitated the disease transmission despite the high 2-dose vaccination coverage in the community.

Characterizing measles transmission in India: a dynamic modeling study using verbal autopsy data

BACKGROUND

Decreasing trends in measles mortality have been reported in recent years. However, such estimates of measles mortality have depended heavily on assumed regional measles case fatality risks (CFRs) and made little use of mortality data from low- and middle-income countries in general and India, the country with the highest measles burden globally, in particular.

METHODS

We constructed a dynamic model of measles transmission in India with parameters that were empirically inferred using spectral analysis from a time series of measles mortality extracted from the Million Death Study, an ongoing longitudinal study recording deaths across 2.4 million Indian households and attributing causes of death using verbal autopsy. The model was then used to estimate the measles CFR, the number of measles deaths, and the impact of vaccination in 2000-2015 among under-five children in India and in the states of Bihar and Uttar Pradesh (UP), two states with large populations and the highest numbers of measles deaths in India.

RESULTS

We obtained the following estimated CFRs among under-five children for the year 2005: 0.63% (95% confidence interval (CI): 0.40-1.00%) for India as a whole, 0.62% (0.38-1.00%) for Bihar, and 1.19% (0.80-1.75%) for UP. During 2000-2015, we estimated that 607,000 (95% CI: 383,000-958,000) under-five deaths attributed to measles occurred in India as a whole. If no routine vaccination or supplemental immunization activities had occurred from 2000 to 2015, an additional 1.6 (1.0-2.6) million deaths for under-five children would have occurred across India.

CONCLUSIONS

We developed a data- and model-driven estimation of the historical measles dynamics, CFR, and vaccination impact in India, extracting the periodicity of epidemics using spectral and coherence analysis, which allowed us to infer key parameters driving measles transmission dynamics and mortality.

The Immune Response in Measles: Virus Control, Clearance and Protective Immunity

Measles is an acute systemic viral infection with immune system interactions that play essential roles in multiple stages of infection and disease. Measles virus (MeV) infection does not induce type 1 interferons, but leads to production of cytokines and chemokines associated with nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) signaling and activation of the NACHT, LRR and PYD domains-containing protein (NLRP3) inflammasome. This restricted response allows extensive virus replication and spread during a clinically silent latent period of 10–14 days. The first appearance of the disease is a 2–3 day prodrome of fever, runny nose, cough, and conjunctivitis that is followed by a characteristic maculopapular rash that spreads from the face and trunk to the extremities. The rash is a manifestation of the MeV-specific type 1 CD4⁺ and CD8⁺ T cell adaptive immune response with lymphocyte infiltration into tissue sites of MeV replication and coincides with clearance of infectious virus. However, clearance of viral RNA from blood and tissues occurs over weeks to months after resolution of the rash and is associated with a period of immunosuppression. However, during viral RNA clearance, MeV-specific antibody also matures in type and avidity and T cell functions evolve from type 1 to type 2 and 17 responses that promote B cell development. Recovery is associated with sustained levels of neutralizing antibody and life-long protective immunity.

[Measles: the disease, epidemiology, history and vaccination programs in Chile]

Measles, one of most important inmuno-preventable diseases, remains as a worldwide concern issue with an important morbidity and mortality. Particularly in the America region declared free of measles in 2010 by WHO, they still appear imported cases that origin outbreaks of variable magnitude in susceptible subjects usually none vaccinated which is the current situation in Santiago, the capital city of Chile. In this review we present characteristics of the etiological agent, the disease, epidemiological aspects with national historical focus, impact of immunization programs and outbreaks in Chile, in order to contribute to knowledge and management of this always present public health problem.

Potential Impact of Co-Infections and Co-Morbidities Prevalent in Africa on Influenza Severity and Frequency: A Systematic Review

Infectious diseases and underlying medical conditions common to Africa may affect influenza frequency and severity. We conducted a systematic review of published studies on influenza and the following co-infections or co-morbidities that are prevalent in Africa: dengue, malaria, measles, meningococcus, Pneumocystis jirovecii pneumonia (PCP), hemoglobinopathies, and malnutrition. Articles were identified except for influenza and PCP. Very few studies were from Africa. Sickle cell disease, dengue, and measles co-infection were found to increase the severity of influenza disease, though this is based on few studies of dengue and measles and the measles study was of low quality. The frequency of influenza was increased among patients with sickle cell disease. Influenza infection increased the frequency of meningococcal disease. Studies on malaria and malnutrition found mixed results. Age-adjusted morbidity and mortality from influenza may be more common in Africa because infections and diseases common in the region lead to more severe outcomes and increase the influenza burden. However, gaps exist in our knowledge about these interactions.

Measles: pathology, management and public health issues

Measles is a highly contagious viral disease that continues to occur in epidemics in the UK despite efforts to eradicate it. In the acute stage, measles is associated with several complications including otitis media, but some of the most severe consequences of the disease occur months and even years after the initial infection. Worldwide, measles contributes significantly to deaths in childhood and places an additional burden on families already living with the consequence of poverty and conflict. This article aims to develop the reader's understanding of measles, including its pathophysiology, management and associated public health issues.

Maternal, fetal, and neonatal outcomes associated with measles during pregnancy: Namibia, 2009-2010

BACKGROUND

Previous studies of maternal, fetal, and neonatal complications of measles during pregnancy suggest the possibility of increased risk for morbidity and mortality. In 2009-2011, a nationwide laboratory-confirmed measles outbreak occurred in Namibia, with 38% of reported cases among adults. This outbreak provided an opportunity to describe clinical features of measles in pregnant women and assess the relative risk for adverse maternal, fetal, and neonatal outcomes.

METHODS

A cohort of pregnant women with clinical measles was identified retrospectively from 6 district hospitals and clinics over a 12-month period. Each pregnant woman with measles was matched with 3 pregnant women without measles, randomly selected from antenatal clinic registers at the same hospital during the same time interval. We reviewed hospital and clinic records and conducted in-person interviews to collect demographic and clinical information on the pregnant women and their infants.

RESULTS

Of 55 pregnant women with measles, 53 (96%) were hospitalized; measles-related complications included diarrhea (60%), pneumonia (40%), and encephalitis (5%). Among pregnant women with known human immunodeficiency virus (HIV) status, 15% of those without measles and 19% of those with measles were HIV positive. Of 42 measles-related pregnancies with known outcomes, 25 (60%) had ≥1 adverse maternal, fetal, or neonatal outcome and 5 women (12%) died. Compared with 172 pregnancies without measles, after adjusting for age, pregnancies with measles carried significantly increased risks for neonatal low birth weight (adjusted relative risk [aRR] = 3.5; 95% confidence interval [CI], 1.5-8.2), spontaneous abortion (aRR = 5.9; 95% CI, 1.8-19.7), intrauterine fetal death (aRR = 9.0; 95% CI, 1.2-65.5), and maternal death (aRR = 9.6; 95% CI, 1.3-70.0).

CONCLUSIONS

Our findings suggest that measles virus infection during pregnancy confers a high risk of adverse maternal, fetal, and neonatal outcomes, including maternal death. Maximizing measles immunity among women of childbearing age would decrease the incidence of gestational measles and the attendant maternal, fetal, and neonatal morbidity and mortality.

Sustained autophagy contributes to measles virus infectivity

The interplay between autophagy and intracellular pathogens is intricate as autophagy is an essential cellular response to fight against infections, whereas numerous microbes have developed strategies to escape this process or even exploit it to their own benefit. The fine tuned timing and/or selective molecular pathways involved in the induction of autophagy upon infections could be the cornerstone allowing cells to either control intracellular pathogens, or be invaded by them. We report here that measles virus infection induces successive autophagy signallings in permissive cells, via distinct and uncoupled molecular pathways. Immediately upon infection, attenuated measles virus induces a first transient wave of autophagy, via a pathway involving its cellular receptor CD46 and the scaffold protein GOPC. Soon after infection, a new autophagy signalling is initiated which requires viral replication and the expression of the non-structural measles virus protein C. Strikingly, this second autophagy signalling can be sustained overtime within infected cells, independently of the expression of C, but via a third autophagy input resulting from cell-cell fusion and the formation of syncytia. Whereas this sustained autophagy signalling leads to the autophagy degradation of cellular contents, viral proteins escape from degradation. Furthermore, this autophagy flux is ultimately exploited by measles virus to limit the death of infected cells and to improve viral particle formation. Whereas CD150 dependent virulent strains of measles virus are unable to induce the early CD46/GOPC dependent autophagy wave, they induce and exploit the late and sustained autophagy. Overall, our work describes distinct molecular pathways for an induction of self-beneficial sustained autophagy by measles virus.

Autophagy is an evolutionarily conserved lysosomal dependent degradative pathway for recycling of long-lived proteins and damaged organelles. Autophagy is also an essential cellular response to fight infection by destroying infectious pathogens trapped within autophagosomes and plays a key role in the induction of both innate and adaptive immune responses. Numerous viruses have evolved strategies to counteract autophagy in order to escape from degradation or/and to inhibit immune signals. The kinetic and molecular pathways involved in the induction of autophagy upon infections might determine if cells would be able to control pathogens or would be invaded by them. We showed that measles virus (MeV) infection induces successive autophagy signallings in cells via distinct molecular pathways. A first autophagy wave is induced by the engagement of the MeV cellular receptor CD46 and the scaffold protein GOPC. A second wave is initiated after viral replication by the expression of the non-structural MeV protein C and is sustained overtime within infected cells thanks to the formation of syncytia. This sustained autophagy is exploited by MeV to limit the death of infected cells and to improve viral particle formation. We describe new molecular pathways by which MeV hijacks autophagy to promote its infectivity.

Wild-type measles virus infection upregulates poliovirus receptor-related 4 and causes apoptosis in brain endothelial cells by induction of tumor necrosis factor-related apoptosis-inducing ligand

Small numbers of brain endothelial cells (BECs) are infected in children with neurologic complications of measles virus (MV) infection. This may provide a mechanism for virus entry into the central nervous system, but the mechanisms are unclear. Both in vitro culture systems and animal models are required to elucidate events in the endothelium. We compared the ability of wild-type (WT), vaccine, and rodent-adapted MV strains to infect, replicate, and induce apoptosis in human and murine brain endothelial cells (HBECs and MBECs, respectively). Mice also were infected intracerebrally. All MV stains productively infected HBECs and induced the MV receptor PVRL4. Efficient WT MV production also occurred in MBECs. Extensive monolayer destruction associated with activated caspase 3 staining was observed in HBECs and MBECs, most markedly with WT MV. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), but not Fas ligand, was induced by MV infection. Treatment of MBECs with supernatants from MV-infected MBEC cultures with an anti-TRAIL antibody blocked caspase 3 expression and monolayer destruction. TRAIL was also expressed in the endothelium and other cell types in infected murine brains. This is the first demonstration that infection of low numbers of BECs with WT MV allows efficient virus production, induction of TRAIL, and subsequent widespread apoptosis.

[Blueberry muffin baby. A rare presentation of congenital cytomegalovirus infection]

The 'blueberry muffin baby' designation was used to describe the cutaneous manifestations of congenital rubella. The differential diagnosis includes other TORCH infections, blood dyscrasias, neoplasms, or vascular disorders. We present a case of a newborn admitted at birth for presenting disseminated violaceous cutaneous nodules. Pregnancy was full term and without infectious complications, with prenatal diagnosis of restrictive intrauterine growth, hydramnios and suspected esophageal atresia. Maternal serology with no evidence of infection. The newborn blood study showed thrombocytopenia, direct hyperbilirubinemia, elevated transaminases and coagulopathy. During hospitalization he showed progressive hepatosplenomegaly. Skin biopsy showed extramedullary erythropoiesis. Myelogram revealed absence of megakaryocytic line precursors. The molecular analysis for cytomegalovirus in peripheral blood and bone marrow was positive. Cerebral ultrasound examination revealed bilateral calcifications and periventricular hyperechogenicity. The placental anatomopathological exam showed features suggestive of cytomegalovirus infection. On the fifth day of life was initiated ganciclovir. This case presentation is intended to emphasize that although it is a rare manifestation, congenital cytomegalovirus infection should be considered in the differential diagnosis of 'blueberry muffin baby'.

Virucidal activity of a scorpion venom peptide variant mucroporin-M1 against measles, SARS-CoV and influenza H5N1 viruses

Outbreaks of SARS-CoV, influenza A (H5N1, H1N1) and measles viruses in recent years have raised serious concerns about the measures available to control emerging and re-emerging infectious viral diseases. Effective antiviral agents are lacking that specifically target RNA viruses such as measles, SARS-CoV and influenza H5N1 viruses, and available vaccinations have demonstrated variable efficacy. Therefore, the development of novel antiviral agents is needed to close the vaccination gap and silence outbreaks. We previously identified mucroporin, a cationic host defense peptide from scorpion venom, which can effectively inhibit standard bacteria. The optimized mucroporin-M1 can inhibit gram-positive bacteria at low concentrations and antibiotic-resistant pathogens. In this investigation, we further tested mucroporin and the optimized mucroporin-M1 for their antiviral activity. Surprisingly, we found that the antiviral activities of mucroporin-M1 against measles, SARS-CoV and influenza H5N1 viruses were notably increased with an EC₅₀ of 7.15 μg/ml (3.52 μM) and a CC₅₀ of 70.46 μg/ml (34.70 μM) against measles virus, an EC₅₀ of 14.46 μg/ml (7.12 μM) against SARS-CoV and an EC₅₀ of 2.10 μg/ml (1.03 μM) against H5N1, while the original peptide mucroporin showed no antiviral activity against any of these three viruses. The inhibition model could be via a direct interaction with the virus envelope, thereby decreasing the infectivity of virus. This report provides evidence that host defense peptides from scorpion venom can be modified for antiviral activity by rational design and represents a practical approach for developing broad-spectrum antiviral agents, especially against RNA viruses.

A comparison study of measles antibody between two doses vaccination at 9, 18 months and single dose at 9 months in children 4-6 years old

BACKGROUND

The authors have added the second dose of measles vaccine to children aged 18 months since 1997 because of the measles outbreaks in Nan province in 1993-1994.

OBJECTIVE

To compare measles antibody level between two doses vaccination at 9, 18 months and single dose at 9 months in children at the age of 4 to 6 years old.

MATERIAL AND METHOD

A cross sectional serological study in children 4 to 6 years old was performed between August 2008 and August 2009 at three hospitals in Nan and Phrae provinces. The subjects were divided into two groups, 1) 100 children in Nan provincial hospital received two doses of measles vaccination at the age of 9 and 18 months and 2) 91 children received single dose measles vaccination at the age of 9 months, 41 from Phrae provincial hospital and 50 from Weingsa district hospital. Blood samples were drawn for measles antibody measurement by ELISA assays at Virus Research Institute, National Institute of Health, Thailand.

RESULTS

The mean measles antibody level in children 4 to 6 years old in both groups was a satisfactory high level, 1,887.67 and 1,621.02 mIU/ml in single and two doses vaccination respectively, which were not statistically significant (p = 0.431). The higher level in single dose group could be explained by the average age being younger than the two doses group by one year (4 years 2 months vs. 5 years 4 months). Therefore, the waning immunity in younger age group is suspected to be less than the older age group. The rate of protective measles antibody level (> or = 255 mIU/ml) was significantly higher in the two doses group than the single dose, 87% compared to 76% (p = 0.046), which represented primary vaccine failure at the age 4 to 6 years of 13% and 24%, respectively.

CONCLUSION

The authors suggest that a second dose of measles vaccine at the age of 18 months be administered to decrease the number of primary vaccine failure from 24% to 13%. Further studies in the same age group and in different areas are required to confirm these findings.

[Suspected measles encephalitis caused by modified measles that was difficult to diagnose: a case report]

A 72-year-old man with subacute right upper limb palsy was diagnosed with cerebral infarction at another hospital. However, the head magnetic resonance imaging (MRI) scans showed no abnormalities. He was later transferred to our hospital because of cognitive dysfunctions. Because his symptoms had gradually worsened, a second head MRI was performed on admission. The scans showed an abnormality in the left frontal-parietal lobe, and the serum measles IgM level was elevated. Measles encephalitis was consequently diagnosed and steroid pulse therapy was immediately initiated. The patient recovered with no limb palsy or cognitive dysfunctions. With widespread administration of the measles vaccine, we expect that the incidence of modified measles will increase in the future. Hence the serum titer of the measles virus should be measured when patients with subacute meningoencephalitis of unclear origin are identified.

Letter: Adult measles with a butterfly rash-like appearance

Butterfly rash is characterized by symmetrical erythema and erythematous papules and plaques grouped on the bilateral cheeks and nose, commonly found in lupus erythematosus. Measles is a highly contagious viral disease, characterized by high fever, cough, coryza, conjunctivitis, and Koplik spots, which precede generalized maculo-papular rashes. We report an adult case of measles, accompanied by butterfly rash. A 20-year-old woman came to our hospital with a butterfly rash-like eruption on the face, high fever, and arthralgia. The eruption had appeared on the nose and both cheeks three days before admission. The oral mucosa was not involved. On the basis of the three criteria for a diagnosis of lupus eruthematosus, we first made a tentative diagnosis of lupus eruthematosus and performed blood tests. However, anti-DNA antibodies, scl-70, anti-Ro and La, anti-Sm and rheumatoid factor were all negative. Two days after admission, a Koplik macule appeared along with multiple erythematous macules and papules that were scattered through the trunk. Laboratory tests were positive for anti-measles immunoglobulin M and G. Therefore, we reached a diagnosis of measles. Within a week, all of the clinical symptoms disappeared. Physicians should be aware that, in rare cases, measles may present with a butterfly-like rash.

[Study on characteristic of current measles wild-type strains after continuous passage from Vero cells]

OBJECTIVE

To investigate the change on infection capacity of measles epidemic strain after continuous passage from Vero cell line, and to analyze the possible reasons in genetic level that caused change on cell-recognition site.

METHODS

Measles virus epidemic strain Ningbo 05-2 was continuous passaged from Vero cells and Cytopathic Effect (CPE) was observed and recorded. After confirmation by real-time Reverse Transcription-Polymerase Chain Reaction (RT-PCR), hemagglutinating activity of Ningbo 05-2/P18 was detected using hemagglutination (HA) test and the completed sequences within Hemagglutinin (H) and Necleoprotein (N) gene were amplified by RT-PCR.

RESULTS

Measles epidemic strain Ningbo 05-2 has been continuous cultured for 17 times (P18) on Vero cells, but CPE began to be observed from the 13th passage. Although the passaged strains were confirmed as measles virus by real-time RT-PCR, the hemagglutinating activity of Ningbo 05-2/P18 was still negative. Compared with the Ningbo 05-2, there were three amino acid mutations within H protein of Ningbo 05-2/P18 (312aa, 314aa, 546aa), which changed the beta-sheet on the 311aa and the beta-turn during 312aa to 316aa to the alpha-helix. Phylogenetic tree based on H gene indicated the Ningbo 05-2/P18 still belonged to sub-genotype H(1b), locating at the same branch with the original strain. However, sequences of the original and passaged strains were identical within N protein.

CONCLUSIONS

Only a few amino acid mutations within H protein could results in cell-recognition site alternative of measles epidemic strain after continuous culture in Vero cell line, and consequently affecting the infection of measles virus.

[Analysis on clinical characteristics of adult measles inpatients in Urumqi Municipal]

OBJECTIVES

To analyze the clinical and laboratory characteristics, and characteristics of population distribution as well, and to provide the scientific data for the adult measles control.

METHODS

Using descriptive epidemiology and statistical approach to analyze the clinical information for the adult measles patients hospitalized in People's Hospital of Xinjiang Uygur Autonomous Region of Urumqi city in Xinjiang province of China between Oct. 2007 and Mar. 2008.

RESULTS

The average age of all the patients was 25.5 years old. 63 patients had fever and most of them were at 39.1-40.0'C. 61(96.8%) patients had rash, and 54 (85.7%) patients had koplik spots at the moment of hospitalization. 26 (41.3%) patients had the complications of acute tracheobronchitis. And the chest radiograph of 28 (44.4%) patients showed the inflammatory shadow. The proportion of the neutrophils of 11 (17.5%) patients was high level in the blood testing. The alanine aminotransferase of 18 (28.6%) patients were elevated. All the patients were recovery.

CONCLUSION

More and more adult measles patients occurred in China in recent years. The clinical characteristics among the patients was variable. It is necessary to discuss and make a decision about the issue of supplementary immunization for adult population in China.

Human precision-cut liver tumor slices as a tumor patient-individual predictive test system for oncolytic measles vaccine viruses

Availability of an individualized preselection of oncolytic viruses to be used for virotherapy of tumor patients would be of great help. Using primary liver tumor resection specimens we evaluated the precision-cut liver slice (PCLS) technology as a novel in vitro test system for characterization of paramount tumor infection parameters of individual patients. PCLS slices from resection specimens of 20 liver tumor patients were cultivated in vitro for up to 5 days and infected with 5 different oncolytic measles vaccine virus (MeV) strains. Effectiveness of tumor infection was monitored by viral nucleocapsid (N) protein detection in immunofluorescence staining or Western blot analysis or by detection of GFP marker gene expression. MeV spreading in PCLS cultures was visualized by confocal microscopy. Oncolytic MeV vaccine particles were demonstrated to efficiently infect PCLS slices originating from different primary and secondary tumors of the liver with MeV strains Moraten/Edmonston Zagreb and AIK-C showing highest infection rates (75% of all tested tumor specimens). Employing mixed liver tissue slices (exhibiting both tumorous and non-tumorous tissue areas on one and the same sample) a distinct tumor area favouring pattern of MeV infections was observed being in accordance with our finding that primary human hepatocytes are also permissive to MeV particles, albeit at a much lower rate and with a much less pronounced cytopathic effect. Furthermore, confocal microscopy demonstrated virus penetration throughout tumor tissues into deep cell layers. In conclusion, the PCLS technology is suitable to perform a tumor-patient individualized preselection of oncolytic agents prior to clinical virotherapeutic applications.

Otosclerosis: an organ-specific inflammatory disease with sensorineural hearing loss

Otosclerosis is an inflammatory disease associated with persistent measles virus (MV) infection of the otic capsule. The nature of sensorineural hearing loss (SNHL) related to otosclerosis can be due to the chronic TNF-alpha release from the foci. TNF-alpha enters the inner ear fluid spaces in histologically active stages of otosclerosis and may cause outer hair cell functional disorder and subsequent SNHL without morphological changes of the organ of Corti. On the contrary, non-otosclerotic stapes ankylosis being a non-inflammatory disease is not harmful for hair cells. Theoretically, SNHL should not associate to this type of stapes fixation. Stapes footplates (N = 248) were examined by hematoxylin-eosin staining and corresponding MV-, OPG- and TNF-alpha-specific RT-PCR. Anti-measles IgG levels of serum specimens were measured by ELISA. Preoperative audiological results were correlated with otosclerotic and non-otosclerotic histopathologies. Among patients with stapes fixation, we found 93 active and 67 inactive otosclerosis, and 88 non-otosclerotic stapes ankylosis. MV could only be detected in otosclerotic stapes footplates. Audiometry revealed bone conduction threshold elevation toward the high frequencies in otosclerotic patients, which was associated to the duration of hearing loss. OPG mRNA expression was significantly lower in the TNF-alpha positive specimens, which was independent from virus positivity. In about one-third of stapes fixations, the etiology is non-otosclerotic stapes ankylosis. Histologic otosclerosis exhibits a strong correlation with MV presence in the bone as a sign of persistent MV infection and related inflammation with TNF-alpha release. This causes SNHL in the function of time. Non-otosclerotic stapes fixations do not cause high-frequency SNHL.

[Measles]

Measles are a systemic infectious disease caused by a single stranded ribonucleic acid virus (measles virus) from the paramyxovirus family. Typically, the disease is characterized by a two-phase course. After an average incubation period of 8 to 11 days, initial symptoms such as fever, cough, coryza and conjunctivitis appear. Two thirds of the patients shows a white-marked enanthema on the buccal mucosa (Koplik's spots). After disappearance of these symptoms, a second increase of temperature and the typical measles exanthema, a brownish-red maculopapular rash, appear. Infection with measles virus induces transient immunodeficiency that favours the formation of several complications. Some of them, e. g. encephalitic diseases, are severe and associated with a high mortality. Measles are world-wide distributed and belong to the ten most frequent infectious diseases in some less developed countries. The disease is associated with a high mortality in some African and South-East Asian countries, in particular in children aged less than 12 months. Of particular note, measles are the most important cause of blindness in children in population with borderline vitamin A status. In Germany, the number of reported measles cases has been declined dramatically since the introduction of a vaccine more than four decades ago. However, regional outbreaks or small epidemics still occur. Because there is no specific antiviral treatment, therapy of measles is symptomatic and depends on the manifestation of the disease. The most important prevention strategy is immunization with a life-attenuated vaccine that can be applied as monovaccination or in combination with mumps and rubella virus (MMR vaccination) or mumps, rubella and varicella virus (MMRV vaccination).

Measles studies in the macaque model

Much of our current understanding of measles has come from experiments in non-human primates. In 1911, Goldberger and Anderson showed that macaques inoculated with filtered secretions from measles patients developed measles, thus demonstrating that the causative agent of this disease was a virus. Since then, different monkey species have been used for experimental measles virus infections. Moreover, infection studies in macaques demonstrated that serial passage of the virus in vivo and in vitro resulted in virus attenuation, providing the basis for all current live-attenuated measles vaccines. This chapter will review the macaque model for measles, with a focus on vaccination and immunopathogenesis studies conducted over the last 15 years. In addition, recent data are highlighted demonstrating that the application of a recombinant measles virus strain expressing enhanced green fluorescent protein dramatically increased the sensitivity of virus detection, both in living and sacrificed animals, allowing new approaches to old questions on measles vaccination and pathogenesis.

An Immunocompetent Murine Model for Oncolysis with an Armed and Targeted Measles Virus

An immunocompetent model is required to test therapeutic regimens for clinical trials with the oncolytic measles virus (MV). Toward developing this model, a retargeted MV that enters murine colon adenocarcinoma cells forming tumors in syngeneic C57BL/6 mice was generated. Since MV infection tends to be less efficient in murine than in human cells, the targeted virus was also armed with the prodrug convertase, purine nucleoside phosphorylase (PNP), and named MV-PNP-antiCEA. We have shown before that in cultured cells, infection with this virus activated the prodrug, 6-methylpurine-2'-deoxyriboside (MeP-dR), causing extensive cytotoxicity. When injected intratumorally (IT), MV-PNP-antiCEA inhibited subcutaneous tumor growth marginally, but subsequent administration of the prodrug enhanced the oncolytic effect. Systemic delivery of MV-PNP-antiCEA alone had no substantial oncolytic effects, but in combination with the prodrug it was therapeutic, revealing synergistic effects between virus and prodrug. Immunosuppression with cyclophosphamide (CPA) retarded the appearance of MV neutralizing antibodies and enhanced oncolytic efficacy: survival was 100%, with 9 out of 10 animals going into complete remission. This immunocompetent murine model facilitates the testing of therapeutic regimens for clinical trials.

Clinical and genetic characterization of measles viruses isolated from adult patients in Shanghai in 2006

BACKGROUND

In recent years there has been an increase in adult measles cases in Shanghai, and an outbreak occurred in 2005. Although there have been many studies analyzing the genotype of measles virus from pediatric patients in various parts of China, there is little information on the clinical findings and genetic makeup of adult measles.

OBJECTIVES

Clinical information and phylogenetic analysis of adult measles infection in Shanghai.

STUDY DESIGN

Blood, urine, throat swabs, and clinical information were collected from adult measles patients reporting to three major hospitals in Shanghai. Measles virus was isolated in Vero-SLAM cells. The C-terminus of the N gene of the isolates was sequenced and analyzed with reference to sequences obtained from GenBank.

RESULTS

More than half of the patients developed severe clinical symptoms. None of the patients knew their measles vaccination history. All measles virus isolates had the same amino acid substitutions as the two standard H1a measles strains at position 484 and were classified as H1a genotype and could be further divided into three small clusters.

CONCLUSIONS

The genotype of the predominant measles virus causing disease in adults in Shanghai is H1a.

Bronchoalveolar cellularity and interleukin-8 levels in measles bronchiolitis obliterans

BACKGROUND

Measles virus infection may progress to a chronic obstructive process including bronchiolitis obliterans (BO). This study investigates pulmonary cellular profiles and interleukin (IL)-8 levels in patients with BO following the measles.

METHODS

BAL fluid was obtained from 12 children with BO who had a history of measles pneumonia during an outbreak in 2000 and 2001. BAL cell counts and differentials were compared to control patients as well as BAL IL-8 levels, which were measured by enzyme-linked immunosorbent assay. Immunohistochemical staining of BAL cells and three open-lung biopsy specimens were also analyzed for T-cell surface markers CD3, CD4, and CD8.

RESULTS

BAL cellular profiles were characterized by a significantly increased percentage of neutrophils in the measles BO group (median, 16.0%) compared to the control group (2.3%) [p < 0.01]. BAL IL-8 levels were also markedly increased in the measles BO group (mean +/- SD, 418.6 +/- 286.0 pg/mL) compared to the control group (92.8 +/- 126.7 pg/mL) [p < 0.01]. BAL IL-8 levels correlated significantly with neutrophil percentages in both the measles BO group (r = 0.86, p = 0.000) and the control group (r = 0.79, p = 0.007). The lymphocyte subsets were characterized by a significantly increased number of CD8+ cells, resulting in a decreased CD4/CD8 ratio in the BAL and the biopsy specimens.

CONCLUSION

These results suggest that pulmonary neutrophils and IL-8, along with CD8+ T lymphocytes may play an important role in the pathogenesis of BO after measles virus infection.

Lung involvement in childhood measles: severe immune dysfunction revealed by quantitative immunohistochemistry

Measles, accounting for nearly 1 million deaths each year, presents intense involvement of lymphoid organs and the lungs. The immune response in situ in the lungs was determined in blocks recovered from 42 necropsies of children who died from measles determined by immune cell phenotype (CD4, CD8, CD20, CD45RO, CD68, natural killer [NK], and antigen S-100 B [S100]) and cytokine production (interferon, tumor necrosis factor, interleukin [IL]-1, IL-2, IL-4, IL-10, and IL-12). Compared with the lungs of age-paired controls, patients with measles presented severe depletion of CD4+, CD20+, CD68+, NK+, and S100+ cells in alveolus- and bronchus-associated lymphoid tissue without depletion of CD8+ cells. Most of these features were similar in both forms of measles lung involvement, Hecht giant cell, or interstitial pneumonia, but S100+ cells were depleted in bronchus-associated lymphoid tissue from patients with Hecht pneumonia, which also occurs more frequently in malnourished children. IL-10- and IL-12-producing cells were depleted in patients with measles, whereas IL-1-, interferon-, and IL-4-producing cells were more frequently seen in the alveolus of patients with measles compared with controls. Quantitative in situ immune cell phenotype and function in the lung in measles demonstrated severe immune dysfunction, with loss of key cells, such as dendritic, CD4+, and NK+ cells, and deficient cytokine production, which allows for a better comprehension of local reactions in this process.

Measles virus prevalence in otosclerotic foci

The etiology of otosclerosis is still unknown. Persistent measles virus infection of the otic capsule is supposed to be one of the etiologic factors in otosclerosis. The presence of measles virus was shown in otosclerotic patients by RT-PCR amplification of the viral RNA, detecting the viral proteins by immunohistochemistry and antimeasles immunoglobulin G in the perilymph samples. Nucleic acid (mRNA, vRNA, DNA) was extracted from pulverized, frozen stapes footplate samples of otosclerotic patients. Measles virus RNA was amplified by RT-PCR: reverse transcription and the first-round PCR amplification were performed by heat-stable recombinant Thermus thermophilus polymerase, while in the nested round PCR Taq polymerase was employed. Oligonucleotide primers specific to measles virus nucleoprotein and matrix protein RNA were used in these reactions. Edmonston- and Schwartze-type measles viruses served as positive controls and cortical bone fragments, stapes superstructures, cadaver stapes, incus and malleolar samples served as negative controls. Among 102 otosclerotic patients, 62 stapes footplate samples contained measles virus RNA. Measles virus RNA was not detected in other bone specimens of the patients. The etiologic role of measles virus in the pathogenesis of otosclerosis should be considered. The 40 negative samples may be genetically determined otosclerotic cases or stapes fixations due to other causes.

Measles virus: cellular receptors, tropism and pathogenesis

Measles virus(MV), a member of the genusMorbillivirusin the familyParamyxoviridae, is an enveloped virus with a non-segmented, negative-strand RNA genome. It has two envelope glycoproteins, the haemagglutinin (H) and fusion proteins, which are responsible for attachment and membrane fusion, respectively. Human signalling lymphocyte activation molecule (SLAM; also called CD150), a membrane glycoprotein of the immunoglobulin superfamily, acts as a cellular receptor for MV. SLAM is expressed on immature thymocytes, activated lymphocytes, macrophages and dendritic cells and regulates production of interleukin (IL)-4 and IL-13 by CD4+T cells, as well as production of IL-12, tumour necrosis factor alpha and nitric oxide by macrophages. The distribution of SLAM is in accord with the lymphotropism and immunosuppressive nature of MV.Canine distemper virusandRinderpest virus, other members of the genusMorbillivirus, also use canine and bovine SLAM as receptors, respectively. Laboratory-adapted MV strains may use the ubiquitously expressed CD46, a complement-regulatory molecule, as an alternative receptor through amino acid substitutions in the H protein. Furthermore, MV can infect SLAM−cells, albeit inefficiently, via the SLAM- and CD46-independent pathway, which may account for MV infection of epithelial, endothelial and neuronal cellsin vivo. MV infection, however, is not determined entirely by the H protein–receptor interaction, and other MV proteins can also contribute to its efficient growth by facilitating virus replication at post-entry steps. Identification of SLAM as the principal receptor for MV has provided us with an important clue for better understanding of MV tropism and pathogenesis.

A mouse model of persistent brain infection with recombinant Measles virus

Measles virus (MV) nucleocapsids are present abundantly in brain cells of patients with subacute sclerosing panencephalitis (SSPE). This invariably lethal brain disease develops years after acute measles as result of a persistent MV infection. Various rodent models for MV infection of the central nervous system (CNS) have been described in the past, in which the detection of viral antigens is based on histological staining procedures of paraffin embedded brains. Here, the usage of a recombinant MV (MV-EGFP-CAMH) expressing the haemagglutinin (H) of the rodent-adapted MV-strain CAM/RB and the enhanced green fluorescent protein (EGFP) is described. In newborn rodents the virus infects neurons and causes an acute lethal encephalitis. From 2 weeks on, when the immune system of the genetically unmodified animal is maturating, intracerebral (i.c.) infection is overcome subclinically, however, a focal persistent infection in groups of neurons remains. The complete brain can be analysed in 50 or 100 microm slices, and infected autofluorescent cells are readily detected. Seven and 28 days post-infection (p.i.) 86 and 81% of mice are infected, respectively, and virus persists for more than 50 days p.i. Intraperitoneal immunization with MV 1 week before infection, but not after infection, protects and prevents persistence. The high percentage of persistence demonstrates that this is a reliable and useful model of a persistent CNS infection in fully immunocompetent mice, which allows the investigation of determinants of the immune system.

High pathogenicity of wild-type measles virus infection in CD150 (SLAM) transgenic mice

Measles virus (MV) infection causes an acute childhood disease, associated in certain cases with infection of the central nervous system and development of a severe neurological disease. We have generated transgenic mice ubiquitously expressing the human protein SLAM (signaling lymphocytic activation molecule), or CD150, recently identified as an MV receptor. In contrast to all other MV receptor transgenic models described so far, in these mice infection with wild-type MV strains is highly pathogenic. Intranasal infection of SLAM transgenic suckling mice leads to MV spread to different organs and the development of an acute neurological syndrome, characterized by lethargy, seizures, ataxia, weight loss, and death within 3 weeks. In addition, in this model, vaccine and wild-type MV strains can be distinguished by virulence. Furthermore, intracranial MV infection of adult transgenic mice generates a subclinical infection associated with a high titer of MV-specific antibodies in the serum. Finally, to analyze new antimeasles therapeutic approaches, we created a recombinant soluble form of SLAM and demonstrated its important antiviral activity both in vitro and in vivo. Taken together, our results show the high susceptibility of SLAM transgenic mice to MV-induced neurological disease and open new perspectives for the analysis of the implication of SLAM in the neuropathogenicity of other morbilliviruses, which also use this molecule as a receptor. Moreover, this transgenic model, in allowing a simple readout of the efficacy of an antiviral treatment, provides unique experimental means to test novel anti-MV preventive and therapeutic strategies.

[Measles in two children and one adult--outbreak of measles genotype B3]

Measles virus genotype B3 was isolated from patients during a measles outbreak in Copenhagen starting January 2006. Here we describe three cases: two children aged 9 and 22 months, respectively, and a 29-year-old man. All three patients were hospitalised. Several doctors examined both the children before the diagnosis of measles was established. The patients were not vaccinated against measles. They had not been abroad within the last three weeks. Genotype B3 is endemic in West and Central Africa. The genotype B3 detected in these cases was different from the B3 seen in recent outbreaks in Europe.

MRI findings from a case of fulminating adult-onset measles encephalitis

We report a rare case of fulminating adult-onset measles encephalitis. A 34-year-old man developed a comatose state after measles eruptions and ultimately akinetic mutism. Titers of anti-measles IgM antibodies were elevated in both serum and cerebrospinal fluid. Brain magnetic resonance imaging (MRI) 3 months after onset revealed widespread hyperintense lesions in the periventricular white matter and marginal hyperintense lesions in the brainstem on fluid-attenuated inversion recovery and diffusion-weighted images. The marginal lesions in the brainstem are similar to subpial demyelinating lesions seen in postinfectious encephalomyelitis. This case of encephalitis may be related to an autoimmune-mediated process triggered by measles infection.