Immune responses to measles and measles vaccine: challenges for measles control

Acute Demyelinating Encephalomyelitis Following Measles Infection Due to Vaccine Failure: A Case Report

Introduction

Local outbreaks of measles infection are primarily mediated by international travel of persons from endemic areas, with subsequent spread of the virus via undervaccinated populations. Recent resurgences of measles in communities where vaccination rates are non-ideal secondary to philosophical objections require the emergency physician to more routinely consider the diagnosis. In cases of measles complicated by acute encephalitis or encephalopathy, the diagnosis can be especially difficult to make due to lack of a reliable primary historian.

Case report

Here we present a case of altered mental status and new-onset bilateral lower extremity weakness in a fully vaccinated young woman diagnosed with measles infection caused by acute disseminated encephalomyelitis in the setting of vaccine failure.

Conclusion

Despite a documented history of immunization, acute measles infection and its uncommon sequelae are possible. Recognizing vaccine failure and appropriately isolating patients are of paramount importance.

Vaccine-associated enhanced disease: Case definition and guidelines for data collection, analysis, and presentation of immunization safety data

This is a Brighton Collaboration Case Definition of the term “Vaccine Associated Enhanced Disease” to be utilized in the evaluation of adverse events following immunization. The Case Definition was developed by a group of experts convened by the Coalition for Epidemic Preparedness Innovations (CEPI) in the context of active development of vaccines for SARS-CoV-2 vaccines and other emerging pathogens. The case definition format of the Brighton Collaboration was followed to develop a consensus definition and defined levels of certainty, after an exhaustive review of the literature and expert consultation. The document underwent peer review by the Brighton Collaboration Network and by selected Expert Reviewers prior to submission.

Effects of Social Housing Changes on Immunity and Vaccine-Specific Immune Responses in Adolescent Male Rhesus Macaques

Nonhuman primates (NHPs) in research institutions may be housed in a variety of social settings, such as group housing, pair housing or single housing based on the needs of studies. Furthermore, housing may change over the course of studies. The effects of housing and changes in housing on cell activation and vaccine mediated immune responses are not well documented. We hypothesized that animals moved indoors from group to single housing (GH-SH) would experience more stress than those separated from groups into pair housing (GH-PH), or those placed briefly into pair housing and separated 5 weeks later into single housing (GH-PH-SH). We also compared the effects of separation from group to pair housing with the separation from pair to single housing. Eighteen male rhesus macaques were followed over the course of changes in housing condition over 10–14 weeks, as well as prior to and after primary vaccination with a commercially available measles vaccine. We identified two phenotypic biomarkers, namely total CD8 population and proliferating B cells, that differed significantly across treatment groups over time. At 10 weeks post-separation, levels of proliferating B cells were higher in GH-SH subjects compared to GH-PH subjects, and in the latter, levels were lower at 10 weeks than prior to removal from group housing. At 2 weeks post-separation from group to single housing, the frequency of CD8+ T cells was higher in GH-SH subjects compared to one week post separation from pair into single housing in the GH-PH-SH subjects. Comparing the same elapsed time since the most recent separation activated CD20 populations were persistently higher in the GH-SH animals than the GH-PH-SH animals. Housing configuration did not influence vaccine-mediated responses. Overall, our study found benefits of pair housing over single housing, suggesting that perturbations in immune function will be more severe following separation from group to single housing than from pair to single housing, and supporting the use of short-duration pair housing even when animals must subsequently be separated. These findings are useful for planning the housing configurations of research NHPs used for vaccine studies and other studies where immune response is being assessed.

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.

Descriptive epidemiology of rubella disease and associated virus strains in Uganda

Rubella virus causes a mild disease; however, infection during the first trimester of pregnancy may lead to congenital rubella syndrome (CRS) in over 80% of affected pregnancies. Vaccination is recommended and has been shown to effectively reduce CRS incidence. Uganda plans to introduce routine rubella vaccination in 2019. The World Health Organization recommends assessing the disease burden and obtaining the baseline molecular virological data before vaccine introduction. Sera collected during case-based measles surveillance from January 2005 to July 2018 were tested for rubella immunoglobulin M (IgM) antibodies. Sera from confirmed rubella outbreaks from January 2012 to August 2017 were screened using real-time reverse-transcription polymerase chain reaction (RT-PCR); for positive samples, a region within the E1 glycoprotein coding region was amplified and sequenced. Of the 23 196 suspected measles cases serologically tested in parallel for measles and rubella, 5334 (23%) were rubella IgM-positive of which 2710 (50.8%) cases were females with 2609 (96.3%) below 15 years of age. Rubella IgM-positive cases were distributed throughout the country and the highest number was detected in April, August, and November. Eighteen (18%) of the 100 sera screened were real-time RT-PCR-positive of which eight (44.4%) were successfully sequenced and genotypes 1G and 2B were identified. This study reports on the seroprevalence and molecular epidemiology of rubella. Increased knowledge of former and current rubella viruses circulating in Uganda will enhance efforts to monitor the impact of vaccination as Uganda moves toward control and elimination of rubella and CRS.

Immunogenicity and Safety of the Measles Vaccine in HIV-Infected Children: An Updated Systematic Review

Children infected with human immunodeficiency virus (HIV) are at increased risk of measles morbidity and mortality. We searched abstracts from the PubMed, Embase, and Latin American and Caribbean Center on Health Sciences Information databases for articles published from the earliest date available through September 26, 2017. The primary outcome of interest was serological responses to measles vaccine, stratified by HIV infection status. A total of 2,858 potentially eligible articles were identified, and the final review included 12 studies published between 1992 and 2013, 9 of which reported data on vaccine safety. The studies we included represented 3,573 children, of whom at least 335 were infected with HIV, 788 were HIV-exposed but not infected, and 1,478 were unexposed to HIV. Four of the 12 studies found statistically significant reductions in seropositivity among HIV-infected children compared with HIV-uninfected children within 4 months of vaccination (prevalence ratio range, 0.44-0.70), and forest plots provided visual trends of decreasing immunity over time among HIV-infected children in 2 additional studies. No vaccine-related deaths or serious adverse events were reported. This updated review demonstrated limitations of the existing published literature but supported evidence of reduced immunogenicity of measles vaccine among HIV-infected children, supporting the World Health Organization recommendation to revaccinate HIV-infected children against measles following immune reconstitution with combination antiretroviral therapy.

Genetic Variants in the IL-4/IL-13 Pathway Influence Measles Vaccine Responses and Vaccine Failure in Children from Mozambique

Despite effective measles vaccines, measles still causes severe morbidity and mortality worldwide, particularly in developing countries. The Th2 pathway involving interleukin (IL)-4 and IL-13 cytokines, and their receptor IL-4Rα, play important roles in the Th1/Th2 balance and antibody production. A Th2 skewing of the cytokine milieu may affect vaccine responses. We investigated IL-4, IL-13, and IL-4Rα polymorphisms and their impact on measles IgG responses and measles vaccine failure, in two separate cohorts: 12-month-old Australian children immunized with measles-mumps-rubella vaccine (n = 137) and a case/control cohort of children aged 6 months-14 years from Mozambique, Africa (n = 89), some of whom were vaccinated, but still contracted measles (vaccine failure). We found that IL-4Rα haplotypes for Val75Ile, Ser503Pro, and Arg576Gln were associated with measles IgG in Mozambican children (p = 0.016 and p = 0.032 for Val.Pro.Arg and Val.Ser.Arg, respectively), but not Australian children. IL-4Rα 503Pro was more prevalent in Mozambique vaccine failure cases compared with controls (p = 0.008). We showed that the impact of Th2 genes on measles vaccine responses differs between ethnicities and IL-4Rα polymorphisms may work in combination to affect measles antibody responses and vaccine failure in Mozambican children. Studies in this area are particularly important in developing countries like Mozambique where measles is still a major health issue.

Hemagglutinin protein of measles virus induces apoptosis of HeLa cells via both extrinsic and intrinsic pathways

In this study, we investigated the potential for different components of the measles virus (MV) to induce apoptosis of HeLa cells and explored the apoptotic molecular mechanisms. After testing the 2 envelope glycoproteins hemagglutinin (H) and fusion (F), we found that MV H alone was sufficient to induce the apoptosis of HeLa cells, whereas MV F did not. MV F also had no influence on MV-H-mediated apoptosis. MV H could induce cellular apoptosis in HeLa cells through its interaction with the cellular receptor CD46 via both the TRAIL-mediated extrinsic pathway and the mitochondria-controlled intrinsic pathway, and that cross talk between these 2 pathways occurred during the process. These findings extend the functions of MV envelope glycoproteins in the pathogenesis of MV infection and suggest that MV H may be a potential therapeutic in the treatment of some cancers.

Timeliness vaccination of measles containing vaccine and barriers to vaccination among migrant children in East China

Background

The reported coverage rates of first and second doses of measles containing vaccine (MCV) are almost 95% in China, while measles cases are constantly being reported. This study evaluated the vaccine coverage, timeliness, and barriers to immunization of MCV₁ and MCV₂ in children aged from 8–48 months.

Methods

We assessed 718 children aged 8–48 months, of which 499 children aged 18–48 months in September 2011. Face to face interviews were administered with children’s mothers to estimate MCV₁ and MCV₂ coverage rate, its timeliness and barriers to vaccine uptake.

Results

The coverage rates were 76.9% for MCV₁ and 44.7% for MCV₂ in average. Only 47.5% of surveyed children received the MCV₁ timely, which postpone vaccination by up to one month beyond the stipulated age of 8 months. Even if coverage thus improves with time, postponed vaccination adds to the pool of unprotected children in the population. Being unaware of the necessity for vaccination and its schedule, misunderstanding of side-effect of vaccine, and child being sick during the recommended vaccination period were significant preventive factors for both MCV₁ and MCV₂ vaccination. Having multiple children, mother’s education level, household income and children with working mothers were significantly associated with delayed or missing MCV₁ immunization.

Conclusions

To avoid future outbreaks, it is crucial to attain high coverage levels by timely vaccination, thus, accurate information should be delivered and a systematic approach should be targeted to high-risk groups.

An in-host model of acute infection: measles as a case study

The epidemiology of acute infections is strongly influenced by the immune status of individuals. In-host models can provide quantitative predictions of immune status and can thus offer valuable insights into the factors that influence transmission between individuals and the effectiveness of vaccination protocols with respect to individual immunity. Here we develop an in-host model of measles infection. The model explicitly considers the effects of immune system memory and CD8 T-cells, which are key to measles clearance. The model is used to determine the effects of waning immunity through vaccination and infection, the effects of booster exposures or vaccines on the level of immunity, and the immune system characteristics that result in measles transmission (R(0)>1) even if an individual has no apparent clinical symptoms. We find that the level of immune system CD8 T-cells at the time of exposure to measles determines whether an individual will experience a measles infection or simply a boost in immunity. We also find that the infected cell dynamics are a good indicator of measles transmission and the degree of symptoms that will be experienced. Our results indicate that the degree of immunity in adults is independent of the source of exposure in early childhood, be it vaccine or natural infection.

Live vaccines for human metapneumovirus designed by reverse genetics

Human metapneumovirus (HMPV) was first described in 2001 and has quickly become recognized as an important cause of respiratory tract disease worldwide, especially in the pediatric population. A vaccine against HMPV is required to prevent severe disease associated with infection in infancy. The primary strategy is to develop a live-attenuated virus for intranasal immunization, which is particularly well suited against a respiratory virus. Reverse genetics provides a means of developing highly characterized 'designer' attenuated vaccine candidates. To date, several promising vaccine candidates have been developed, each using a different mode of attenuation. One candidate involves deletion of the G glycoprotein, providing attenuation that is probably based on reduced efficiency of attachment. A second candidate involves deletion of the M2-2 protein, which participates in regulating RNA synthesis and whose deletion has the advantageous property of upregulating transcription and increasing antigen synthesis. A third candidate involves replacing the P protein gene of HMPV with its counterpart from the related avian metapneumovirus, thereby introducing attenuation owing to its chimeric nature and host range restriction. Another live vaccine strategy involves using an attenuated parainfluenza virus as a vector to express HMPV protective antigens, providing a bivalent pediatric vaccine. Additional modifications to provide improved vaccines will also be discussed.

Measles virus nucleoprotein induces cell-proliferation arrest and apoptosis through NTAIL-NR and NCORE-FcgammaRIIB1 interactions, respectively

Measles virus (MV) nucleoprotein (N) is a cytosolic protein that is released into the extracellular compartment after apoptosis and/or secondary necrosis of MV-infected cells in vitro. Thus, MV-N becomes accessible to inhibitory cell-surface receptors: FcgammaRIIB and an uncharacterized nucleoprotein receptor (NR). MV-N is composed of two domains: NCORE (aa 1-400) and NTAIL (aa 401-525). To assess the contribution of MV-N domains and of these two receptors in suppression of cell proliferation, a human melanoma HT144 cell line expressing (HT144IIB1) or lacking FcgammaRIIB1 was used as a model. Specific and exclusive NCORE-FcgammaRIIB1 and NTAIL-NR interactions were shown. Moreover, NTAIL binding to human NR predominantly led to suppression of cell proliferation by arresting cells in the G0/G1 phases of the cell cycle, rather than to apoptosis. NCORE binding to HT144IIB1 cells primarily triggered caspase-3 activation, in contrast to HT144IIB1/IC- cells lacking the FcgammaRIIB1 intra-cytoplasmic tail, thus demonstrating the specific inhibitory effect of the NCORE-FcgammaRIIB1 interaction. MV-N- and NCORE-mediated apoptosis through FcgammaRIIB1 was inhibited by the pan-caspase inhibitor zVAD-FMK, indicating that apoptosis was dependent on caspase activation. By using NTAIL deletion proteins, it was also shown that the region of NTAIL responsible for binding to human NR and for cell growth arrest maps to one of the three conserved boxes (Box1, aa 401-420) found in N of Morbilliviruses. This work unveils novel mechanisms by which distinct domains of MV-N may display different immunosuppressive activities, thus contributing to our comprehension of the immunosuppressive state associated with MV infection. Finally, MV-N domains may be good tools to target tumour cell proliferation and/or apoptosis.

Measles Virus 1998–2002: Progress and Controversy

Despite the extensive media exposure that viruses such as West Nile, Norwalk, and Ebola have received lately, and the emerging threat that old pathogens may reappear as new agents of terrorism, measles virus (MV) persists as one of the leading causes of death by infectious agents worldwide, approaching the annual mortality rate of human immunodeficiency virus (HIV)-1. For most MV victims, fatality is indirect: Virus-induced transient immunosuppression predisposes the individual to opportunistic infections that, left untreated, can result in mortality. In rare cases, MV may also cause progressive neurodegenerative disease. During the past five years (1998-2002), development of animal models and the application of reverse genetics and immunological assays have collectively contributed to major progress in our understanding of MV biology and pathogenesis. Nevertheless, questions and controversies remain that are the basis for future research. In this review, major advances and current debates are discussed, including MV receptor usage, the cellular basis of immunosuppression, the suspected role of MV in "nonviral" diseases such as multiple sclerosis and Paget's disease, and the controversy surrounding MV vaccine safety.

The challenge of improving the efficacy of measles vaccine

Despite a safe and effective measles vaccine, measles still claims an estimated 800,000 lives per year mostly among children in developing countries. This paper deals with strategies to improve vaccine efficacy and prevent unnecessary deaths, including considerations of one dose at 9 months strategy for developing countries, strain of vaccine, potency and number of doses of measles vaccine. After more than 20 years of measles immunisation in the developing world, the epidemiology of measles is radically changed, and the absence of measles epidemics might lead to waning immunity due to less clinical and subclinical infections boosting the antibody level. An increasing proportion of mothers are vaccinated, thus transferring a lower maternal antibody level to their infants who will be susceptible to measles at a younger age. The strategies to limit nosocomial measles infection and spread of measles epidemics are reviewed. Though the measles elimination programmes have been very effective in the Americas, it seems unlikely that they will be equally effective in the rest of the world. Even if eradication should be possible, it might be unwise to stop measles vaccination because the vaccine apparently has beneficial effects and because it would make measles a likely weapon for bio-terrorism. If we are unlikely to get rid of measles and measles vaccine, it might be wise to study further some of the many unanswered questions regarding the long-term effects of measles and measles vaccination.