Measles Virus Variants Research Articles

Evaluation of the sensitivity of a measles diagnostic real-time RT-PCR assay incorporating recently observed priming mismatch variants, 2024.

We investigated a variant of measles virus that encodes three mismatches to the reverse priming site for a widely used diagnostic real-time RT-PCR assay; reduction of sensitivity was hypothesised. We examined performance of the assay in context of the variant using in silico data, synthetic RNA templates and clinical specimens. Sensitivity was reduced observed at low copy numbers for templates encoding the variant sequence. We designed and tested an alternate priming strategy, rescuing the sensitivity of the assay.

Identification of a measles variant displaying mutations impacting molecular diagnostics, Geneva, Switzerland, 2023.

Real-time PCR is one of the most widely used techniques to diagnose measles cases. Here we report measles virus variants with three genetic mutations in the reverse primer annealing site of a widely used PCR. The mutations result in a slight loss of the PCR sensitivity. Variants bearing the three mutations presently circulate in different countries since at least the end of 2021. Our findings highlight the usefulness of molecular surveillance in monitoring if oligonucleotides in diagnostic tests remain adequate.

Diagnostic reference value of antibody levels measured using enzyme immunoassay for subacute sclerosing panencephalitis.

High measles-specific antibody titers in the cerebrospinal fluid (CSF) have important diagnostic significance for subacute sclerosing panencephalitis (SSPE), a progressive neurological disorder caused by measles virus variants. However, the diagnostic reference value of antibody levels and the usefulness of the CSF/serum ratio measured using enzyme immunoassays (EIAs) for SSPE diagnosis remain unclear. To facilitate SSPE diagnosis using EIAs, measles immunoglobulin G (IgG) titers in the CSF and serum of patients with and without SSPE were measured and their CSF/serum antibody ratios evaluated. Serum and CSF antibody levels were compared among three patients with SSPE (59 paired samples), 37 non-SSPE patients, and 2618 patients of unknown backgrounds. Of the 59 paired samples from three patients with SSPE, 56 paired samples (94.9%) showed CSF measles IgG levels ≥0.5 IU/mL and a CSF/serum ratio ≥0.05, whereas non-SSPE cases showed CSF measles IgG levels <0.1 IU/mL and a CSF/serum ratio <0.03. Of the 2618 CSF samples with unknown backgrounds, 951 showed measurable IgG levels with EIA, with a CSF/serum ratio peak of 0.005-0.02, with a 90th percentile of 0.05. Assuming the SSPE criteria as CSF measles IgG ≥0.5 IU/mL and a CSF/serum ratio ≥0.05, only 20 samples (0.8%) with unknown backgrounds were categorized as having SSPE. Conversely, assuming the non-SSPE criteria as CSF measles IgG <0.1 IU/mL and a CSF/serum ratio <0.03, 2403 samples (92%) with unknown backgrounds were categorized as not having SSPE. In conclusion, high CSF/serum ratios (≥0.05) and high measles CSF IgG levels (≥0.5 IU/mL) may be useful for diagnosing SSPE.

Upregulation of viral RNA polymerase activity promotes adaptation of SSPE virus to neuronal cells

Subacute sclerosing panencephalitis (SSPE) is a rare progressive neurodegenerative disease caused by measles virus variants (SSPE viruses) that results in eventual death. Amino acid substitution(s) in the viral fusion (F) protein are key for viral propagation in the brain in a cell-to-cell manner, a specific trait of SSPE viruses, leading to neuropathogenicity. In this study, we passaged an SSPE virus in cultured human neuronal cells and isolated an adapted virus that propagated more efficiently in neuronal cells and exhibited increased cell-to-cell fusion. Contrary to our expectation, the virus harbored mutations in the large protein, a viral RNA-dependent RNA polymerase, and in the phosphoprotein, its co-factor, rather than in the F protein. Our results imply that upregulated RNA polymerase activity, which increases F protein expression and cell-to-cell fusion, could be a viral factor that provides a growth advantage and contributes to the adaptation of SSPE viruses to neuronal cells.

Genetic characterisation of Measles virus variants identified during a large epidemic in Milan, Italy, March-December 2017.

In 2017, Italy experienced a large measles epidemic with 5408 cases and four deaths. As Subnational Reference Laboratory of the Measles and Rubella surveillance NETwork (MoRoNET), the EpiSoMI (Epidemiology and Molecular Surveillance of Infections) Laboratory (University of Milan) set up rapid and active surveillance for the complete characterisation of the Measles virus (Mv) responsible for the large measles outbreak in Milan and surrounding areas (Lombardy, Northern Italy). The aims of this study were to describe the genetic profile of circulating viruses and to track the pathway of measles transmission. Molecular analysis was performed by sequencing the highly variable 450 nucleotides region of the N gene (N-450) of Mv genome. Two-hundred and ninety-nine strains of Mv were analysed. The phylogenetic analysis showed five different variants, two not previously described in the studied area, belonging to D8 and B3 genotypes. Three events of continuous transmission of autochthonous variants (D8-Osaka, D8-London and B3-Milan variants) and two events of continuous transmission of imported variants (B3-Dublin and D8-Hulu Langat) tracked five different transmission pathways. These pathways outlined two epidemic peaks: the first in April and the second in July 2017. The correlation between Mv variant and the epidemiological data may enable us to identify the sources of virus importation and recognise long-lasting virus transmission pathways.

Potential of Genetically- Modified Measles Virus as A Treatment Modality For Carcinoma: A Review

Malignancy is a disease in which cell division is uncontrolled and prognosis is often poor. Despite recent advances in the felid of medicine the life expectancy after the diagnosis of advanced stages of cancers has high mortality rates . The traditional methods of treatment have low curative effects and high risk of side effects. Further the possibility of re-occurrence is not completely eliminated by any of the conventional methods of treatment. Thus, a technique that affects only the tumour cells without leaving behind any cancer initiator cells must be deviced. Recently genetically modified variants of measles virus were used to cure multiple myeloma .The idea to use of measles virus dates back to 1950’s.Constant research has lead the advent of a branch known as oncolytic virotheraphy . Precise targeting of cancer cells is one of the dominant advantages of cancer therapy through virus and it can be achieved in multiple manners. A few viruses such as exclusively replicating mumps virus, moloney leukemia virus, parvoviruses, reovirus, newcastle disease virus have a natural preference for malignant cells, whereas vesicular stomatitis adenovirus, virus, measles, vaccinia and herpes simplex virus can be adapted or engineered to make them cancer-specific.

Measles in Italy: Co-circulation of B3 variants during 2014.

In 2013, the majority of the WHO/EUR countries reported an annual incidence of >1 case per one million population indicating that the elimination target is far from being met. Thus, there is the urgent need to uncover and analyze chains of measles virus (MV) transmission with the objective to identify vulnerable groups and avoid possible routes of introduction of MV variants in the European population. The analysis of molecular epidemiology of MV B3 strains identified in 2014 has shown that four different variants co-circulated in Italy, including the strain that caused a cruise-line ship outbreak at the beginning of the year.

Central Nervous System Diseases Due to Slow Viruses and Prions

Several central nervous system diseases whose common elements include a long incubation period and a progressive clinical course were once called slow virus infections, because most of them are in fact caused by viruses. However, one group of these CNS diseases is now believed to be caused by abnormally configured proteins known as prions; rather than an etiologic designation, therefore, on the whole these diseases are better characterized by their chronicity, their transmissibility, and at this point, their inexorably deteriorating natural history. This chapter reviews the more common of these: HIV-associated dementia (HAD or HIVD), human T cell lymphotropic virus type 1 (HTLV-1)-associated myelopathy, Creutzfeldt-Jakob disease (CJD), progressive multifocal leukoencephalopathy (PML), and subacute sclerosing encephalitis (SSPE), which is associated with a variant of measles virus. Figures illustrate the pathogenesis and the pathology of HIV dementia, propagation of scrapie prion protein (PrP) in brain neurons, and spongiform brain changes of CJD. Tables list the stages of HAD and the clinical and pathologic characteristics distinguishing classic CJD and varient CJD. This module contains ­5 highly rendered figures, 2 tables, 57 references, and 5 MCQs.

Measles fusion machinery is dysregulated in neuropathogenic variants.

ABSTRACTParamyxoviruses, including the human pathogen measles virus (MV), enter host cells by fusing their viral envelope with the target cell membrane. This fusion process is driven by the concerted actions of the two viral envelope glycoproteins, the receptor binding protein (hemagglutinin [H]) and the fusion (F) protein. H attaches to specific proteinaceous receptors on host cells; once the receptor engages, H activates F to directly mediate lipid bilayer fusion during entry. In a recent MV outbreak in South Africa, several HIV-positive people died of MV central nervous system (CNS) infection. We analyzed the virus sequences from these patients and found that specific intrahost evolution of the F protein had occurred and resulted in viruses that are “CNS adapted.” A mutation in F of the CNS-adapted virus (a leucine-to-tryptophan change present at position 454) allows it to promote fusion with less dependence on engagement of H by the two known wild-type (wt) MV cellular receptors. This F protein is activated independently of H or the receptor and has reduced thermal stability and increased fusion activity compared to those of the corresponding wt F. These functional effects are the result of the single L454W mutation in F. We hypothesize that in the absence of effective cellular immunity, such as HIV infection, MV variants bearing altered fusion machinery that enabled efficient spread in the CNS underwent positive selection.

Long-term transmission of measles virus in Central and continental Western Europe.

The World Health Organization (WHO) has adopted an elimination goal for measles and rubella, which is supposed to be met in the WHO European Region (EUR) by 2015. For verification of elimination, it is required that the genotyping data of detected measles viruses provide evidence for the interruption of endemic transmission. In order to record and assess the extent of endemic measles virus (MV) circulation in a part of the EUR, we analyzed transmission chains of the epidemiologically most relevant MV variants identified in Central and continental Western Europe (CCWE) from 2006 to 2013. Based on MV sequence data deposited in the WHO global database for molecular surveillance of measles (MeaNS), the circulation period was calculated for each MV variant at the country-level and for the entire region of CCWE. The MV variants "D5-Okinawa," "D4-Hamburg," "D4-Manchester," and "D8-Frankfurt-Main" spread widely in CCWE; they caused large and long-lasting outbreaks with secondary spread that resulted in additional outbreaks. Nation-wide outbreaks (epidemics) with thousands of measles cases occurred in four countries (Switzerland, France, Bulgaria, and Romania) and were characterized by continuous detection of the same MV variant for more than 12 months suggesting endemic transmission. In the entire region of CCWE, the circulation period of the four predominant MV variants ranged from 18 to 44 months. The long-lasting MV transmission which affected predominantly unvaccinated individuals in different hard-to-reach groups and in the general population is not consistent with the measles elimination goal. Additional efforts are necessary to meet the elimination target in the EUR.

Cell-to-cell transmission in the pathogenesis of human T-lymphotropic virus type 1-associated myelopathy/tropical spastic paraparesis

Virus transmission is an important key factor for understanding the pathomechanism(s) of virus-related neurological diseases. In the past, cell-free transmission was believed to be a major route of virus spread for almost all viruses. However, attention was paid to “cell-to-cell transmission” in the 1960s. Cell-to-cell transmission appears to be more effective, as progeny viruses do not have to encounter antibodies. Although this mode of virus transmission was first highlighted in subacute sclerosing panencephalitis caused by a variant of measles virus, human T-lymphotropic virus type 1 (HTLV-I) also utilizes cell-to-cell transmission. The transmission is undergone through so-called “virological synapses”, a structure first described in HTLV-I. Cell contact induces polarization of the cytoskeleton of the infected cells to the cell–cell junction. HTLV-I core (Gag protein) complexes and the HTLV-I genome accumulate at the cell–cell junction and are transferred to the uninfected cell. The intracellular cyclic adenosine monophosphate regulates the efficiency of intercellular HTLV-I transmission under the control of expression phosphorylated vasodilator- stimulated phosphoprotein.

Mutations in the H, F, or M Proteins Can Facilitate Resistance of Measles Virus to Neutralizing Human Anti-MV Sera

Although there is currently no evidence of emerging strains of measles virus (MV) that can resist neutralization by the anti-MV antibodies present in vaccinees, certain mutations in circulating wt MV strains appear to reduce the efficacy of these antibodies. Moreover, it has been hypothesized that resistance to neutralization by such antibodies could allow MV to persist. In this study, we use a novel in vitro system to determine the molecular basis of MV's resistance to neutralization. We find that both wild-type and laboratory strain MV variants that escape neutralization by anti-MV polyclonal sera possess multiple mutations in their H, F, and M proteins. Cytometric analysis of cells expressing viral escape mutants possessing minimal mutations and their plasmid-expressed H, F, and M proteins indicates that immune resistance is due to particular mutations that can occur in any of these three proteins that affect at distance, rather than directly, the native conformation of the MV-H globular head and hence its epitopes. A high percentage of the escape mutants contain mutations found in cases of Subacute Sclerosing Panencephalitis (SSPE) and our results could potentially shed light on the pathogenesis of this rare fatal disease.

Interferon production by cells infected with subacute sclerosing panencephalitis (SSPE) virus or measles virus

Background: Subacute sclerosing panencephalitis (SSPE) is a rare progressive neurodegenerative encephalitis caused by some variants of measles virus (MV). The structure of SSPE virus in the brains of SSPE patients is different from that of MV. The difference in interferon (IFN) production between cells infected with SSPE virus and those infected with MV remains unclear.Methods: We measured the concentrations of IFN-α, β, γ, and λ1 (interleukin (IL)-29) from MV- or SSPE virus-infected B95a cells (a marmoset B-lymphoblastoid cell line).Results: SSPE virus-infected B95a cells produced significantly higher levels of IFN-α and λ1 than did MV-infected or mock-infected cells.Conclusion: Our results suggest that SSPE virus and MV induce different IFN production profiles.

Crystallization and preliminary crystallographic analysis of the measles virus hemagglutinin in complex with the CD46 receptor.

The measles virus (MV) hemagglutinin (MV-H) mediates the attachment of MV particles to cell-surface receptors for entry into host cells. MV uses two receptors for attachment to host cells: the complement-control protein CD46 and the signalling lymphocyte activation molecule (SLAM). The MV-H glycoprotein from an Edmonston MV variant and the MV-binding fragment of the CD46 receptor were overproduced in mammalian cells and used to crystallize an MV-H-CD46 complex. Well diffracting crystals containing two complexes in the asymmetric unit were obtained and the structure of the complex was solved by the molecular-replacement method.

Single-point mutations of the M protein of a measles virus variant obtained from a patient with subacute sclerosing panencephalitis critically affect solubility and subcellular localization of the M protein and cell-free virus production

Subacute sclerosing panencephalitis (SSPE) is caused by variants of wild-type measles virus (MV). Such MV variants lack almost completely the ability to produce cell-free progeny virus. We recently isolated an MV variant that has only three amino acid mutations (L165P,L250P and Y282H) in the M protein compared with MV field isolates of the same genotype. In the present study, we analyzed the significance of these mutations with regard to the characteristics of the M protein and progeny virus production. We found that each of the three mutations rendered the M protein insoluble in 0.5% Triton X-100 and altered its subcellular localization, either when ectopically expressed alone using a plasmid-based expression system or when expressed in the context of viral replication. Moreover, each of the three mutations markedly, but not completely, impaired the ability of MV to produce cell-free progeny virus, with the degree of impairment being the same as for all three mutations together. These results suggest the possibility that the changes in the solubility and subcellular localization of the M protein determine the ability to produce cell-free progeny virus, at least to some extent, and play a role in the pathogenicity of variants causing SSPE.

Central Nervous System Diseases due to Slow Viruses and Prions

Several central nervous system diseases whose common elements include a long incubation period and a progressive clinical course were once called slow virus infections, because most of them are in fact caused by viruses. However, one group of these CNS diseases is now believed to be caused by abnormally configured proteins known as prions; rather than an etiologic designation, therefore, on the whole these diseases are better characterized by their chronicity, their transmissibility, and at this point, their inexorably deteriorating natural history. This chapter reviews the more common of these: HIV-associated dementia (HAD or HIVD), human T cell lymphotropic virus type 1 (HTLV-1)-associated myelopathy, Creutzfeldt-Jakob disease (CJD), progressive multifocal leukoencephalopathy (PML), and subacute sclerosing encephalitis (SSPE), which is associated with a variant of measles virus. Figures illustrate the pathogenesis and the pathology of HIV dementia, propagation of scrapie prion protein (PrP) in brain neurons, and spongiform brain changes of CJD. Tables list the stages of HAD and the clinical and pathologic characteristics distinguishing classic CJD and varient CJD. This review contains ­5 highly rendered figures, 2 tables, and 57 references.

Interleukin (IL)-12, IL-2, interferon-γ gene polymorphisms in subacute sclerosing panencephalitis patients

Mutated measles virus variants have been claimed as the causing agent for subacute sclerosing panencephalitis (SSPE) developing several years after the recovery from measles infection. However, immune dysfunction may be considered related to a genetic susceptibility to this rare disease. Interleukin (IL)-2 -330 (rs2069 762) and +160 (rs2069 763), IL-12 p40 3' UTR (rs3213113), and interferon (IFN)-gamma +874 (rs2430561) polymorphisms are screened by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and PCR-sequence-specific priming (SSP) methods in 87 SSPE patients and 106 healthy controls (HCs) as candidate genes of susceptibility. The distribution of the IL12B genotypes (rs3213113) showed a trend for a significant difference (P = .053). The frequency of IL12B C allele (P = .04, OR: 1.6) and CC genotype (P = .03, OR: 3.2) were both higher in SSPE patients than in HC. The IL2 -330 genotypes revealed lower frequencies of GG genotype (P = .03, OR: 0.4) as well as G allele (P = .02, OR: 0.6) in SSPE. IL2 -330+160 TG haplotype was more frequent in patients (P = .005, OR: 1.8), whereas GG haplotype was less frequent, compared to controls (P = .02, OR: 0.6). IFNG +874 polymorphism revealed no difference. These findings implicate possible effects of genetic polymorphisms in the susceptibility to SSPE, which need to be confirmed in other populations.

Hsp72, a Host Determinant of Measles Virus Neurovirulence

Transient hyperthermia such as that experienced during febrile episodes increases expression of the major inducible 70-kDa heat shock protein (hsp72). Despite the relevance of febrile episodes to viral pathogenesis and the multiple in vitro roles of heat shock proteins in viral replication and gene expression, the in vivo significance of virus-heat shock protein interactions is unknown. The present work determined the in vivo relationship between hsp72 levels and neurovirulence of an hsp72-responsive virus using the mouse model of measles virus (MV) encephalitis. Transgenic C57BL/6 mice were created to constitutively overexpress hsp72 in neurons, and these mice were inoculated intracranially with Edmonston MV (Ed MV) at 42 h of age. The mean viral RNA burden in brain was approximately 2 orders of magnitude higher in transgenic animals than in nontransgenic animals 2 to 4 weeks postinfection, and this increased burden was associated with a fivefold increase in mortality. Mice were also challenged with an Ed MV variant exhibiting an attenuated in vitro response to hsp72-dependent stimulation of viral transcription (Ed N-522D). This virus exhibited an attenuated neuropathogenicity in transgenic mice, where mortality and viral RNA burdens were not significantly different from nontransgenic mice infected with either Ed N-522D or parent Ed MV. Collectively, these results indicate that hsp72 levels can serve as a host determinant of viral neurovirulence in C57BL/6 mice, reflecting the direct influence of hsp72 on viral gene expression.

Two Domains That Control Prefusion Stability and Transport Competence of the Measles Virus Fusion Protein

Most viral glycoproteins mediating membrane fusion adopt a metastable native conformation and undergo major conformational changes during fusion. We previously described a panel of compounds that specifically prevent fusion induced by measles virus (MV), most likely by interfering with conformational rearrangements of the MV fusion (F) protein. To further elucidate the basis of inhibition and better understand the mechanism of MV glycoprotein-mediated fusion, we generated and characterized resistant MV variants. Spontaneous mutations conferring drug resistance were confirmed in transient assays and in the context of recombinant virions and were in all cases located in the fusion protein. Several mutations emerged independently at F position 462, which is located in the C-terminal heptad repeat (HR-B) domain. In peptide competition assays, all HR-B mutants at residue 462 revealed reduced affinity for binding to the HR-A core complex compared to unmodified HR-B. Combining mutations at residue 462 with mutations in the distal F head region, which we had previously identified as mediating drug resistance, causes intracellular retention of the mutant proteins. The transport competence and activity of the mutants can be restored, however, by incubation at reduced temperature or in the presence of the inhibitory compounds, indicating that the F escape mutants have a reduced conformational stability and that the inhibitors stabilize a transport-competent conformation of the F trimer. The data support the conclusion that residues located in the head domain of the F trimer and the HR-B region contribute jointly to controlling F conformational stability.

Receptor use by vesicular stomatitis virus pseudotypes with glycoproteins of defective variants of measles virus isolated from brains of patients with subacute sclerosing panencephalitis.

The vaccine or Vero cell-adapted strains of measles virus (MV) have been reported to use CD46 as a cell entry receptor, while lymphotropic MVs preferentially use the signalling lymphocyte activation molecule (SLAM or CD150). In contrast to the virus obtained from patients with acute measles, little is known about the receptor that is used by defective variants of MV isolated from patients with subacute sclerosing panencephalitis (SSPE). The receptor-binding properties of SSPE strains of MV were analysed using vesicular stomatitis virus pseudotypes expressing the envelope glycoproteins of SSPE strains of MV. Such pseudotype viruses could use SLAM but not CD46 for entry. The pseudotype viruses with SSPE envelope glycoproteins could enter Vero cells, which do not express SLAM. In addition, their entry was not blocked by the monoclonal antibody to CD46, pointing to another entry receptor for SSPE strains on Vero cells. Furthermore, the unknown receptor(s), distinct from SLAM and CD46, may be present on cell lines derived from lymphoid and neural cells. Biochemical characterization of the receptor present on Vero cells and SK-N-SH neuroblastoma cells was consistent with a glycoprotein. Identification of additional entry receptors for MV will provide new insights into the mechanism of spread of MV in the central nervous system and possible reasons for differences between MVs isolated from patients with acute measles and SSPE.