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.

[Clinical value of CD64 expression in adults with measles complicating bacterial pneumonia]

OBJECTIVE

To study the clinical value of expression of peripheral blood neutrophil CD64 in adults with measles complicating pneumonia.

METHODS

106 patients were divided into two groups by clinical manifestation and bacteria study: measles complicating bacterial pneumonia group and measles complicating viral pneumonia, using flow cytometry determination of CD64, C-reactive protein (CRP) and white blood cell (WBC) count.

RESULTS

The expression of CD64 in the bacterial pneumonia group with eruptive stage was (32.15 +/- 11.07) MFI, which was significantly higher than that in the group of with recovery stage (10.6 +/- 3.23) MFI (P < 0.01) and viral pneumonia (9.55 +/- 3.48) MFI (P < 0.01). These markers were considered positive if CD64 > or = 8.5 MFI, CRP > or = 10 mg/L and WBC > or = 9.05 x 10(9)/L. Their sensitivity was 78.12%, 80.48% and 59.37%. Their specificity was 76.19% ,67.67% and 64.28%. Their accuracy rate was 77.35%, 74.52%, 61.32%; CD64 has a positive relationship with CRP.

CONCLUSION

Compared to CRP, expression of peripheral blood neutrophil CD64 can be a better marker in the early diagnosis of patients with measles complicating bacterial pneumonia and as one of the indicators of disease conditions.

Rubella and measles seroprevalence among women of childbearing age, Argentina, 2002

To assess rubella and measles susceptibility among women of childbearing age we conducted a cross-sectional seroprevalence study in four cities and one rural area in Argentina. A convenience sample of women aged 15-49 years seeking care in public health-care institutions was selected (n=2804). Serum specimens were tested for rubella and measles IgG antibody titres. The overall susceptibility to rubella and measles was 8.8 and 12.5% respectively. Seroprevalence differences were found for both rubella (P<0.001) and measles (P=0.002) across sites. Rubella seroprevalence was higher in women aged >or=40 years than in younger women (P=0.04). Measles seroprevalence tended to increase with age (P<0.001). Approximately 15% of women aged 15-29 years were not immune to measles. No risk factors were associated with rubella seronegativity; however, age (P<0.001) and having less than four pregnancies (P<0.001) were factors associated with measles seronegativity. Our findings support the introduction of supplemental immunization activities targeting adolescents and young adults to prevent congenital rubella syndrome and measles outbreaks over time.

Severe measles in a young female patient with chronic, generalized Trichophyton rubrum infection showing type 2 helper T cell-dominant immunologic reactivity

An obese 18-year-old girl without a history of atopic dermatitis or a systemic immunosuppressive disorder had severe measles with liver dysfunction and pneumonia. For the previous 3 years she had had a chronic untreated generalized Trichophyton rubrum infection. The rash of the measles tended to spare the fungal lesions, where numerous fungi grew in the stratum corneum. Serum IgE level was markedly elevated (>16,000 IU/mL) and decreased after effective antifungal therapy. Delayed skin hypersensitivity reactions to trichophytin and tuberculin were negative, but the immediate skin hypersensitivity to trichophytin was positive. These data indicate that the patient had acquired hyperproduction of IgE with suppression of cell-mediated immunity, that is, acquired impairment of the balance between type 1 and type 2 helper T cells. In this case, chronic T rubrum infection was thought to have a role in driving a normal balance between type 1 and type 2 helper T cells toward type 2 helper T cell-dominant immunity. The result was deterioration of the measles infection and prolongation of the dermatophytosis.

Novel measles virus genotype, East Timor and Australia

Measles outbreaks in 1999 in Queensland and Victoria, Australia, were caused by a novel strain of clade G virus (proposed name g3). Epidemiologic and molecular evidence supports independent circulation of this virus in Queensland, northern Australia, in addition to importation of the virus by East Timor refugees seeking safe haven in Australia.

[Specific features of the epidemic process of measles and epidemic parotitis in territories with ecologically unfavorable conditions]

Differences in the epidemic process of measles and epidemic parotitis in cities situated at territories with ecologically unfavorable conditions have been established. The intensity of the epidemic process of measles and epidemic parotitis is higher in those cities where a higher total level of pollution has been established. A high level of morbidity in these infections is due to disturbances in the immunological resistance of children living in such cities and, as a consequence, having insufficient postvaccinal immunity. A higher percentage of seronegative children among those immunized against the corresponding infections and a higher morbidity level among this category of the population have been established. To decrease morbidity in measles and epidemic parotitis to the level, sporadic for such cities, a greater coverage of children with immunization (up to 99-99.5%) is necessary.

Viral replication and development of specific immunity in macaques after infection with different measles virus strains

Cynomolgus monkeys (Macaca fascicularis) were experimentally infected with a wild type measles virus (MV) strain (MV-BIL). Following intratracheal inoculation with different infectious doses, the virus could be isolated from peripheral blood mononuclear cells (PBMC), lung lavage cells, and pharyngeal cells. The kinetics of the cell-associated viremia was similar in all infected animals. They developed specific serum IgM, IgG, and neutralizing antibody responses as well as MV-specific T cell-mediated immunity. Monkeys infected intratracheally or intramuscularly with the wild type MV-Edmonston or the attenuated MV-Schwartz strain showed a lower level of PBMC-associated viremia and less pronounced specific IgM responses. Nine months after infection with MV strains, all of the monkeys were protected from intratracheal reinfection with MV-BIL. This monkey model is suitable for study of new generations of vaccines and vaccination strategies for measles.

Measles virus-specific functional antibody responses and viremia during acute measles

Antibody titers measured in functional and immunofluorescent assays were compared with proportions of peripheral blood mononuclear cells infected with measles virus in 8 adults with measles. In addition, a syncytium inhibition assay (SIA) for measuring neutralizing antibody using low-passage virus was compared with a standard plaque neutralization test (PNT). Antibody-dependent cellular cytotoxicity (ADCC) antibody rose later but attained higher titer than neutralizing, antibody-dependent complement-mediated lysis, IgM, or IgG antibodies. When titer changes between specimens from each patient obtained on different days were compared, only ADCC (r = .81, P = .026) and IgM (r = .81, P = .027) antibodies correlated with reductions in viremia. SIA and PNT correlated well (r = .93, P < .001). ADCC may be an important defense against measles. The delay in ADCC antibody relative to other antibodies is unique among viruses studied. The SIA is a useful alternative to the PNT for measuring measles neutralizing antibody.

Detection of measles virus from clinical samples using the polymerase chain reaction

OBJECTIVE

To evaluate the usefulness of the polymerase chain reaction to detect the measles virus sequence using clinical samples.

DESIGN

Centers for Disease Control and Prevention case definition of measles with or without IgM serology as a standard.

SETTING

A laboratory in the Department of Pediatrics of the Hokkaido University Hospital, Sapporo, Japan.

PATIENTS

Thirty-two serum samples, 16 throat swab samples, and nine cerebrospinal fluid samples from 32 patients with measles, including four patients with central nervous system involvement, and one serum sample and two throat swab samples from two patients with modified courses of measles were obtained. Ten serum samples, 10 throat swab samples, and 10 cerebrospinal fluid samples were obtained from patients without apparent measles infection as negative controls.

MEASUREMENTS AND MAIN RESULTS

Sensitivity and specificity were comparable with those as obtained by culture or other methods reported in the literature. The polymerase chain reaction was positive in 24 (75.0%) of 32 by serum samples and in 13 (81.3%) of 16 by throat swab samples from the patients with measles, in contrast to none within the negative control group. In three of the four patients with central nervous system involvement, the measles virus sequence was detected in cerebrospinal fluid samples obtained within 1 day following the onset of the manifestations. All three samples from the patients with modified measles yielded positive results.

CONCLUSIONS

The polymerase chain reaction can be used with sufficient sensitivity and specificity to detect the measles virus sequence using clinical samples. Transient and direct invasion of the central nervous system by this virus at the initial stage of the central nervous system involvement was strongly suggested.

Transcription inhibition and other properties of matrix proteins expressed by M genes cloned from measles viruses and diseased human brain tissue

Ribonucleoprotein (RNP) cores extracted from virions of wild-type (Edmonston strain) measles virus (MV) or obtained from MV-infected cells (cRNP) were shown to be capable of transcribing RNA in vitro but at relatively low efficiency. The tightly bound matrix (M) protein could be effectively removed from virion RNP (vRNP) and from cRNP by exposure to buffers of high ionic strength (0.5 to 1.0 M KCl) but only at pH 8.0 or higher. The vRNP and cRNP cores complexed with M protein exhibited markedly reduced transcriptional activity at increasing concentrations, whereas vRNP and cRNP cores free of M protein exhibited linear and substantially higher transcriptional activity; these data suggest that M protein is the endogenous inhibitor of MV RNP transcription. M-gene cDNA clones derived from three strains of wild-type (wt) MV and 10 clones from mRNAs isolated from the brain tissue of patients who had died from subacute sclerosing panencephalitis (SSPE) and from measles inclusion body encephalitis (MIBE) were recloned in the pTM-1 expression vector driven by the bacteriophage T7 RNA polymerase expressed by a coinfecting vaccinia virus recombinant. All 10 mutant SSPE and MIBE clones expressed in vitro and in vivo M proteins that reacted with monospecific anti-M polyclonal antibody and migrated on polyacrylamide gels to positions identical to or only slightly different from those of the M proteins expressed by wt MV clones. When reconstituted with cRNP cores, the three expressed wt M proteins and 6 of the 10 mutant-expressed M proteins showed equivalent capacity to down-regulate MV transcription. Three of the M proteins from SSPE clones and one from the MIBE clone showed little or no capacity to down-regulate transcription when reconstituted with cRNP cores. The only plausible explanations for loss of transcription inhibition activity by the four SSPE/MIBE M proteins were exceedingly high degrees of hypermutations leading to U-->C transitions and cloning-corrected mutations in the initiator codon (ATG-->ACG) of the four M genes. However, only the hypermutated M protein expressed by the MIBE cDNA clone exhibited virtually no capacity to bind cRNP cores in a reconstitution assay. These experiments provide some preliminary data to support the hypothesis that MV encephalitis may result from certain selective mutations in the M gene.

Increased brain quinolinic acid production in mice infected with a hamster neurotropic measles virus

In order to examine the status of quinolinic acid (QUIN) metabolism in a model of delayed excitotoxic neurodegeneration, the de novo production of QUIN from 3-hydroxyanthranilic acid was assessed in brain homogenates and brain slices of mice injected with hamster neurotropic measles virus. In the hippocampus, which presents exclusive nerve cell loss in this model, the activity of 3-hydroxyanthranilic acid oxygenase, an astrocytic enzyme responsible for the biosynthesis of QUIN, was increased 3.3-fold by 7 days after virus inoculation. Less dramatic increases were observed in the cerebral cortex and the striatum, while cerebellar enzyme activity was not different from control values. In the same brain homogenates, no changes occurred in the activities of kynurenine aminotransferase, the biosynthetic enzyme of the neuroprotectant kynurenic acid, and of the astrocytic marker glutamine synthetase. At 7 days postinoculation, hippocampal slices from virus-treated animals, when exposed to 3-hydroxyanthranilic acid, produced 18 times more QUIN than slices from control animals. Notably, a significant increase was also seen 3 days postinoculation, i.e., at a time when astrocytes had started to proliferate but prior to the onset of neurodegeneration (Eur. J. Neurosci. 3:66-71, 1991). These data suggest that astrocyte-derived QUIN may play a causative role in the occurrence of hippocampal nerve cell loss in measles virus-infected mice.

Laboratory testing in patients with morbilliform viral eruptions

The explosion of immunologic testing capabilities over the past 20 years has enabled clinicians to accurately diagnose many conditions that previously were very difficult to identify solely on a clinical basis. Among these disorders are the viral exanthems. Infections with some of these viruses are of relatively little import (erythema infectiosum), whereas others have more significant consequences (HIV, cytomegalovirus). Clinical suspicions may be pursued more fully now, sometimes even in an office setting.

Laboratory diagnosis of measles infection and monitoring of measles immunization: memorandum from a WHO meeting

Measles infection continues to be a major global health problem, and in many countries the disease is frequently diagnosed on clinical grounds alone, although it is easily confused with other conditions. In order to discuss approaches to improving this situation, a WHO Consultation on Laboratory Diagnosis of Measles Infection and Monitoring of Measles Immunization was held in Glasgow on 7-8 August 1993. The discussions and recommendations made by the participants are summarized in this Memorandum.

[Significance of varicella zoster infection in pregnancy and labor]

The authors observed 25 pregnant or delivering women with varicella and their offsprings from 1986 to 1991. The course of varicella of the pregnant and delivering mothers was generally benign, only one progressive case was observed with pneumonitis after delivery; this woman also recovered upon acyclovir treatment. All but one woman delivered on term, in one case the varicella developed on the 27th gestational week; this woman gave birth to a premature baby of 1180 g who died from a cerebral and lung hemorrhage. No sign of varicella-zoster virus infection was found at the autopsy. No congenital varicella syndrome was observed during the investigation period. Varicella-zoster immunoglobulin was given to 21 newborn babies, immediately after birth. Eight of the newborns developed varicella, the course of the disease was mild in seven cases. One baby who was given no varicella-zoster immunoglobulin and developed progressive varicella recovered after acyclovir therapy. During the investigation period the authors observed three cases of zoster in infants whose mothers had had varicella during pregnancy. The authors discuss the possibilities of prevention of varicella-zoster virus infection of newborns and infants.

Infection of monocytes during measles

Immune suppression has long been recognized to be a consequence of measles and a likely contributor to the secondary complications of this infection. Since measles virus can be isolated from peripheral blood leukocytes during the early phases of infection, it has been widely assumed that measles virus suppresses the immune system by replicating in and damaging T lymphocytes. A reverse transcriptase-polymerase chain reaction (RT-PCR) assay able to detect wild-type strains of measles virus was applied to the study of peripheral blood mononuclear cells (PBMC) during natural measles virus infection. Measles virus RNA was detected by RT-PCR in monocyte-enriched adherent cells up to 6 days after the appearance of the rash. No viral RNA was detected in the lymphocyte-enriched nonadherent cell fraction. The numbers of virus-infected PBMC detected by in situ hybridization ranged from 1 in 125 to 1 in 2500. Dual staining identified infected cells as monocytes. It is concluded that the primary leukocytes infected during measles are monocytes, not lymphocytes. This cellular tropism has implications for understanding the immune suppression associated with measles.

Evidence of persistent measles virus infection in Crohn's disease

Transmission electron microscopy was used to examine the microvasculature of perfusion-fixed tissues from Crohn's disease and control patients. Paramyxovirus-like particles, and inclusions consisting of condensations of nucleocapsid, in giant cells and endothelium at foci of vascular injury were identified in all 9 Crohn's disease patients. Tissues from patients with Crohn's disease were also examined by either in situ hybridisation (n = 10) or immunohistochemistry (n = 15), and compared to inflammatory and noninflammatory controls (n = 22). Hybridisation for measles virus N-protein genomic RNA was positive in all cases of Crohn's disease localising to foci of granulomatous vasculitis and lymphoid follicles. Positive immunohistochemical staining for measles virus nucleocapsid protein was positive in 13 of 15 patients with Crohn's disease, localising to foci of granulomatous inflammation. Hybridisation for measles virus RNA was positive in a minority of control intestinal tissues; viral inclusions were not seen ultrastructurally. Immunostaining was negative in control cases of intestinal tuberculosis. These observations suggest that measles virus is capable of causing persistent infection of the intestine and that Crohn's disease may be caused by a granulomatous vasculitis in response to this virus.

Cell fusion by the envelope glycoproteins of persistent measles viruses which caused lethal human brain disease

Measles virus (MV) rarely induces lethal diseases of the human central nervous system characterized by reduced expression of the viral envelope proteins and by lack of viral budding. The MV envelope contains two integral membrane proteins, termed fusion (F) protein and hemagglutinin (H) protein, and a membrane-associated matrix (M) protein. Previously, analysis of MV genes from autopsy material indicated that the M protein and the F protein intracellular domain are often drastically altered by mutations. Here, we present evidence that truncation of the F protein intracellular domain does not impair fusion function, and we suggest that this alteration interferes with viral budding. Unexpectedly, certain combinations of functional F and H proteins were unable to induce syncytium formation, an observation suggesting that specific F-H protein interactions are required for cell fusion. We also found that three of four H proteins of persistent MVs are defective in intracellular transport, oligosaccharide modification, dimerization, and fusion helper function. Thus, MVs replicating in the brain at the terminal stage of infection are typically defective in M protein and in the two integral membrane proteins. Whereas the M protein appears dispensable altogether, partial preservation of F-protein function and H-protein function seems to be required, presumably to allow local cell fusion. Certain subtle alterations of the F and H proteins may be instrumental for disease development.

Variation in field isolates of measles virus during an 8-year period in Japan

Field isolates of measles virus (MV) during an 8-year period in four areas of Japan, i.e., Osaka, Nagoya, Tokyo and Akita, were classified into three types in regard to the electrophoretic mobility of the hemagglutinin (HA) proteins: S type with small (78K) HA, M type with intermediate (80 K) HA and L type with large (82 K) HA. The type of field isolates was closely related with the geographical location and the year of virus isolation. The S type strain was isolated only in an outbreak from 1983 to 1984, whereas the M and L type strains were isolated between 1983 and 1990. The HA genes of the M and L type strains of MV were found to have a nucleotide substitution which introduces a new potential glycosylation site. In addition, the matrix proteins of all field strains isolated after 1977 showed slower electrophoretic mobility of 42 K than 39 K of the Edmonston and Toyoshima strains. These results indicate that MV strains of different HA types existed concomitantly and that major populations of MV currently circulating in Japan are changing from those prevalent in 1983-1984.

Measles virus-induced autoimmune reactions against brain antigen

Recovery from viral infection is a result of very complex interactions between specific and nonspecific immune reactions and the infectious agent. A variety of immune mechanisms are undoubtedly important factors in this event and operate together in overcoming the infectious process. However, despite much available information about these viral defense mechanisms, it has proved remarkably difficult to assign a determinative role in vivo to any single antiviral immunological mechanism in recovery from a single viral disease, particularly since the immune response to the virus itself may frequently contribute to the pathology of the disease. Furthermore, if virus-induced immune responses are also directed against normal host components, this may set the stage for an autoimmune disease. In this context acute measles encephalomyelitis is of interest since in this disease autoimmune reactions against brain antigens have been observed and considered of pathogenetic importance. In this short review, virological and immunological findings of measles virus infections in a rat model in relation to autoimmune reactions will be presented and the mechanisms by which measles virus may alter host reactivity against self-antigens discussed.

Wild measles virus strain: isolation and identification

Four isolates of measles virus (Gag, Il, Buk and Shed) were obtained from suspensions of mononuclear cells from patients at the active stage of the disease. Vero cells were used for the virus isolation. All the isolates caused in the infected cell culture the appearance of symplasts of differently sized, star- or spindle-shaped multinuclear cells. The specificity of cytopathic effect was proved by the adsorption of monkey erythrocytes on the surface of cells infected by virus. The isolates were identified in virus neutralization (VN) and haemagglutination inhibition (HI) tests with different immune preparations: measles-globulin (standard), hyperimmune sera to rubella and mumps viruses, Sch. Zonne and Sch. Flexneria, as well as with conjugates of sera from measles patients and those vaccinated with live measles vaccine (LMV) L-16.

Activation of human herpesvirus-6 in children with acute measles

Virological and serological studies were carried out prospectively to evaluate the possible activation of human herpesvirus-6 (HHV-6) in 50 infants and children with acute measles by isolation of HHV-6 from peripheral blood and by determining neutralizing antibodies to the virus. All but 5 patients (90%) were seropositive to HHV-6 in the acute stage of measles and 18 (40%) had a significant increase in HHV-6 antibody titers thereafter, whereas only 2 of 27 patients who were initially seropositive to Epstein-Barr virus (EBV) viral capsid antigen (VCA) had a significant rise in antibody titers to EBV VCA. Among 18 patients with a significant increase in HHV-6 titers, the virus was isolated from the peripheral blood mononuclear cells of three patients in the early convalescent stage of measles. These results indicate that activation of HHV-6 may occur frequently a few weeks after primary infection with the measles virus.

Effect of prostaglandin E2 (PGE2) and cyclic adenosine monophosphate (cAMP) upon actin cytoskeleton in human pulmonary fibroblasts (ICP-23) infected by measles virus

The evolution of the actin cytoskeleton after trypsinization and recultivation as well as the effect of the PGE2 modulator and that of the secondary messenger, the cyclic AMP upon the same cytoskeletal proteins in human pulmonary fibroblasts (ICP-23) were studied. The substances were administered simultaneously and after one hour of viral adsorption. Using epifluorescence for pointing out filamentous actin the modifications occurring in this cytoskeletal protein when contacting trypsin and the virus and when PGE2 and cAMP are administered in the experimental variants are observed. Actin arrangement is obviously modified by the viral infection but the restrictive effect of PGE2 and cAMP upon virus replication is correlated with modifications occurring in the actin cytoskeleton.

[The isolation of measles virus strains and the study of their hemagglutinating activity]

Three measles strains Gag, Il, and Buk, were isolated from a suspension of mononuclear cells derived from measles patients in the active stage of the disease. Continuous Vero cell cultures were used for virus isolation. In the infected cell culture, all the isolates produced symplasts of different sizes and star-shaped or spindle-shaped multinuclear cells. The specificity of the cytopathic effect was proved by the adsorption of monkey erythrocytes on the surface of virus-affected cells. The isolates were identified in neutralization and HI tests with different immune preparations: measles gamma-globulin (national standard), hyperimmune rabbit sera to measles (Edmonston strain), rubella, and mumps viruses, S. sonnei and S. flexneri, as well as with sera from measles patients and subjects vaccinated with live measles vaccine L-16. The results of identification attest to isolation of 3 measles virus strains, one of which (Buk) possesses particularly high hemagglutinating activity.

Degree and length of viremia in adults with measles

Measles viremia is thought to peak at onset of rash and diminish rapidly over the subsequent 2-3 days. The length of viremia and the proportion of peripheral blood mononuclear cells (PBMC) infected during measles were investigated in 8 adults. Blood was obtained from 7 patients between days 2 and 4 of rash. Five patients had repeat specimens obtained on day 6 or 7, and 1 patient had samples taken on days 6 and 10. Limiting dilutions of PBMC were cultivated with cord blood PBMC and stimulated with phytohemagglutinin. Virus was identified by syncytia formation and confirmed by immunofluorescent staining. Virus was isolated from all 8 patients. Four of 6 patients were still viremic at day 6 or 7 of rash. Titers ranged from 3 to 5623 TCID50/10(5) PBMC. Adults with measles may have prolonged viremia, and a large proportion of PBMC may be infected.

Comparison of severity of viremia and antibody responses between infants and children with measles

Severity of viremia and neutralizing antibody responses were compared between nine young infants (less than or equal to 10 months) with measles and 18 infants and children (greater than or equal to 11 months) with ordinary measles. Peripheral blood mononuclear cell (PBMC)-associated viremia was detected between the first day of elevation of fever (day 0) and day 5 of the disease in the former group, whereas PBMC-associated and cell-free viremia were detected between day 0 and day 14 in the latter group. The number of infected PBMC during the first 7 days of the disease was 3.22 +/- 1.07 (log10, mean +/- s.d.) per 10 million PBMC in the former group, which was significantly smaller (P = 0.02) than that of the latter group (4.21 +/- 1.18). The former group reached the maximum level of antibody earlier than the latter group.

A measles virus isolate from a child with Kawasaki disease: sequence comparison with contemporaneous isolates from 'classical' cases

We examined the relationship between a measles virus isolate from a child with Kawasaki disease and two contemporaneous wild-type isolates from children with 'classical' measles and the Schwarz vaccine strain. Sequence analysis of 3118 bp from the nucleoprotein, matrix, fusion and haemagglutinin genes of each virus revealed that the isolate from the child with Kawasaki disease was not related to measles vaccine strains and did not contain any of the marked abnormalities previously found in subacute sclerosing panencephalitis isolates, but was more akin to wild-type isolates currently circulating in the U.K. A comparison of our sequences with those obtained from earlier wild-type U.K. isolates suggests significant evolution of measles virus in the U.K. over the last decade.

Overview: measles outbreak on a college campus

Although the introduction of the measles vaccine in the United States in 1963 has led to a marked decrease in the incidence of measles (rubeola), this childhood exanthem has not been eliminated. Since 1983, increases in incidence have been observed. Outbreaks have occurred among previously immunized school and college-age students and unimmunized preschool children, infants, and babies. This article reports a measles outbreak at a state university in Texas and proposes a plan to develop immunity against measles to prevent future outbreaks at college and university campuses.

The immune response to measles virus in mice

The T-helper response to the measles virus nucleoprotein (NP) has been studied in mice. The T-cell proliferative response was measured in lymphocytes from mice immunized with either a vaccinia measles-NP recombinant virus or a mouse neuro-adapted measles virus. A T-cell response was obtained with lymphocytes from H2d or H2k mice when stimulated with either measles virus or the NP expressed in bacteria. The response was CD4+ specific. The T-helper epitopes were mapped using truncated NP peptides. The major epitopes in both H2d and H2k mice were determined to be between amino acids 67-98. A further T-cell epitope (between amino acids 457-525) was identified when H2d mice were immunized with measles virus. Studies to quantitate the precursor cells for these epitopes confirmed that the region 67-98 of NP was immunodominant in both haplotypes immunized with the vaccinia-NP recombinant virus, whereas an additional major epitope was observed in the measles virus-infected H2d mice. The primary structure of the epitopes determined here are compared to predicted T-cell epitope motifs.

Nucleotide sequence of the genes encoding the matrix protein of two wild-type measles virus strains

The nucleotide sequences of the matrix protein (M) genes of two wild-type measles virus (MV) isolates (JM and CM) have been determined and shown to differ in 56 positions; 31 of these differences are located in the non-coding region and 25 in the coding region of the gene. Most (80%) of the mutations in the coding region are changes to the third base of a codon. A maximum parsimony analysis of the available M gene nucleotide sequences allowed the construction of a tree with at least three lineages or subtypes. One wild-type strain (JM) was very similar to a subacute sclerosing panencephalitis virus strain (case B); the second wild-type strain, CM, showed nucleotide sequence similarity with MV from a case of measles inclusion body encephalitis. Both wild-type virus sequences are distinct from those so far determined for vaccine strains.

Diagnosis of measles by fluorescent antibody and culture of nasopharyngeal secretions

An indirect fluorescent antibody test (IFA) was evaluated using commercial mouse anti-measles monoclonal antibody and FITC-labeled goat anti-mouse immunoglobulin. For measles isolation, specimens were inoculated into Rhesus monkey kidney (RMK) cells and, when available, CV-1 cells. 381 specimens were tested by IFA and 408 specimens were cultured from patients suspected of having measles. For the 381 specimens tested by both methods, IFA and culture were positive for 31%, culture alone for 14%, IFA alone for 15%, and both negative for 40%. This study indicates that both IFA and culture are required for maximum measles virus detection. Of the positive specimens, 48% were detected either by IFA only (24%) or culture only (24%). IFA was positive in 69% of the culture-positive specimens and therefore, provided rapid diagnosis for many patients.

Use of immunofluorescence to identify measles virus infections

Monoclonal antibody to measles virus was used successfully to identify measles virus antigen directly in clinical specimens, as well as in cell cultures. Pooled nasopharyngeal-throat swab specimens had a higher yield than throat swabs or urine samples for virus detection. Use of A549 cell cultures in the spin amplification vial assay proved to be highly efficient, allowing virus recognition within 1 to 2 days of inoculation. A combination of appropriately collected specimens, which includes a nasopharyngeal-throat swab, direct antigen detection with monoclonal antibody to measles in an indirect immunofluorescence system, and the spin amplification vial assay using A549 cells provides a sensitive and rapid system for isolation and/or identification of measles virus infections.

Expression of measles virus RNA in peripheral blood mononuclear cells of patients with measles, SSPE, and autoimmune diseases

In order to characterize measles virus (MV) infection in peripheral blood mononuclear cells (PBMCs), RNA was isolated from PBMCs after PHA-stimulation for 72 hr of 9 patients with acute measles, 16 patients with subacute sclerosing panencephalitis (SSPE), 13 patients with various autoimmune diseases, and 16 healthy control donors. The RNA obtained was screened for the presence of MV N (nucleocapsid) gene specific transcripts of either positive or negative orientation in a S1 nuclease protection assay. The sensitivity of this assay allowed us to detect one infected cell in 20,000 PBMCs or 0.1 to 0.05 copies of MV-specific RNA per cell. Using single-stranded DNA or RNA probes expression of MV genomic RNA of negative polarity could be detected in only one case of acute measles and one healthy control donor. Conversely, N-specific transcripts of positive polarity, indicating active transcription, could only be detected in patients with acute measles. In addition, in infected PBMCs and in a persistently MV-infected B cell line positive stranded N-specific transcripts containing leader usually present at very low frequency have been found in relatively increased amounts in comparison with transcripts lacking leader. Whereas the ratio of these RNA species during lytic infection with MV in Vero cells is about 1:50, the ratio found here ranges from 1:3 to 1:10. This altered ratio indicates a specific regulation of MV specific transcription in cells of lymphoid origin that has not been found in any other cell system analyzed.

Role of biased hypermutation in evolution of subacute sclerosing panencephalitis virus from progenitor acute measles virus

We identified an acute measles virus (Nagahata strain) closely related to a defective virus (Biken strain) isolated from a patient with subacute sclerosing panencephalitis (SSPE). The proteins of Nagahata strain measles virus are antigenically and electrophoretically similar to the proteins of Edmonston strain measles virus. However, the nucleotide sequence of the Nagahata matrix (M) gene is significantly different from the M genes of all the acute measles virus strains studied to date. The Nagahata M gene is strikingly similar to the M gene of Biken strain SSPE virus isolated several years later in the same locale. Eighty percent of the nucleotide differences between the Nagahata and Biken M genes are uridine-to-cytosine transitions known as biased hypermutation, which has been postulated to be caused by a cellular RNA-modifying activity. These biased mutations account for all but one of the numerous missense genetic changes predicted to cause amino acid substitutions. As a result, the Biken virus M protein loses conformation-specific epitopes that are conserved in the M proteins of Nagahata and Edmonston strain acute measles viruses. These conformation-specific epitopes are also absent in the cryptic M proteins encoded by the hypermutated M genes of two other defective SSPE viruses (Niigata and Yamagata strains). Nagahata-like sequences are found in the M genes of at least five other SSPE viruses isolated from three continents. These data indicate that Biken strain SSPE virus is derived from a progenitor closely resembling Nagahata strain acute measles virus and that biased hypermutation is largely responsible for the structural defects in the Biken virus M protein.

Do measles early giant cells result from fusion of non-infected cells? An immunohistochemical and in situ hybridization study in a case of morbillous appendicitis

A case of acute appendicitis with features of measles inflammatory reaction is studied. Two types of lymphoid polykaryons are seen: Warthin Finkeldey cells inside germinal centres (LN1 ++, LN2 +, L26 +, MB1 +, MB2 +/-) and multinucleate plasma cells in the lamina propria (mu +, alpha ++, kappa +, lambda +). Both types of polykaryon are devoid of inclusions. The search for viral genetic information by in situ hybridization was negative in these cells. A positive signal was observed in interfollicular mononuclear cells and rare enterocytes. A possible mechanism of fusion from without, acting at the beginning of the disease to induce the appearance of polykaryons, is discussed.

[The isolation of the morbilli virus from the Baikal seal Phoca sibirica and its preliminary characterization]

A morbillivirus was isolated from the organs of a seal (Phoca sibirica) which had died during 1987-1988 epizootic in Baikal. This Baikal seal morbillivirus (BSM) was adapted to Vero cell cultures in which it induced a cytopathic effect developing to complete destruction of the monolayer. Typing of BSM was done by indirect immunofluorescence test and enzyme immunoassay using antibodies to distemper and measles viruses. A method for virus concentration and purification was developed. According to electron microscopic examinations, the virus virions were spherical particles of heterogeneous sizes over 100 nm in diameter. The clinical picture of seal infection, pathological anatomy and histopathology are described. A possible role of BSM in the epizootics of Baikal seals is discussed.

[Virological studies of the virus shedding pattern of natural measles]

Using a novel, highly sensitive cell culture system, B95a cells, I investigated the virus shedding of measles virus (MV) of 47 cases with natural measles. MV was isolated from both peripheral blood leukocytes and respiratory secretions up to 6 days from the onset of the rash. By fractionation of blood, MV was isolated from lymphocytes and monocytes up to 6 days from the onset of the rash, however it disappeared rapidly within 48 hours from the plasma. The duration of positive MV isolation depends on the duration of fever, i.e. infectious MV could not be recovered beyond the 24 hours after the alleviation of fever. The data suggest that in natural measles, infectious MV is shed for a longer period than previously believed. The role of infection of monocyte in the pathogenesis of measles is also suggested.

Further-attenuated measles vaccine: virus passages affect viral surface protein expression, immunogenicity and histopathology pattern in vivo

Measles vaccine viruses Leningrad-16 (L-16) and Moscow-5 (M-5, an L-16-derived clonal variant), at passage levels used for vaccination and after ten further low-multiplicity passages on quail embryo (QE) cells, were compared for (1) immunogenicity, (2) histopathological lesions induced in vivo and (3) surface protein expression within infected cells and on the virion surface. At the 10th passage, viruses evoked a poorer neutralizing antibody response in guinea pigs, induced an earlier appearance of more pronounced pathological lesions and replicated faster in Vero cells than the original viruses. H protein expression increased 1.8-2.3-fold after 10 passages of the L-16 variant, but remained virtually unaltered for the M-5 variant. F protein expression of both 10th-passage variants was 0.5-0.8 that of the original virus variants. A similar two-fold decrease in F protein expression was noted after a single virus passage in guinea pigs. The data implicate the loss of F protein as a cause of reduced immunogenicity of further attenuated measles vaccines.

[A mixed infection of lymphoid cell lines by the human T-lymphotropic retrovirus type I (HTLV-I) and the measles vaccine virus]

Interaction of HTLV-1 and vaccine strain of measles virus (VM-L16) in different T and B cell lines was studied. VM-L16 replicated in T and B cells with a cytopathic effect. At a multiplicity of infection of 1 TCD50 per 10 cells, all the cells in cultures died within 4-13 days. No effect of HTLV-1 on cell sensitivity to VM-L16 was demonstrated. HTLV-1 produced in various T-cell lines had different syncytium-forming activity in XC cell cultures. Cocultivation of C91/pL cells with XC cells led to the formation of multiple syncytia. HUT-102 cells had no such activity. Infection of these cell lines with VM-L16 did not change their properties. Another HTLV-1-infected cell line, MT-2, caused insignificant aggregation of XC cells. Infection of the latter with VM-L16 increased the number of racemations 8-fold, and they consisted of numerous adhesive cells. The cell adhesion, however, which is the first stage of syncytium formation did nor terminate in cytoplasm confluence. MT-2 nad XC cell lines may be used as model systems for the study of various factors influencing HTLV-1 activation.

[The mechanisms of persistent measles virus infection in HEp-2 cells]

Persistent infection with Edmonston strain of measles virus was established in a highly susceptible clone of HEp-2 cells. The morphological and cytogenic aspects of persistent infection are presented. Carriage of measles virus in cells persistently infected is marked by important differences between standard Edmonston strain and virus stocks isolated from time to time from the carrier state. It is especially significant that cell fusion capacity decreased in amount concordant with the drop in the yield of infectious virus. Addition of UV inactivated Sendai virus, trypsin treatment or incubation at suboptimal temperatures precipitate the cytocidal effect of measles virus. Some clinical implications of reactivation of the lytic cycle in the carrier state are suggested.

Mutated and hypermutated genes of persistent measles viruses which caused lethal human brain diseases

Persistent measles viruses (MVs) causing lethal human brain diseases are defective, and the structure of several mutated matrix genes has been elucidated previously. The present study of four persistent MVs revealed a high number of differences from a consensus sequence also in other genes. Amino acid changes accumulated in the carboxyl terminus of the nucleocapsid protein and in the amino terminus of the phosphoprotein, but did not significantly alter these products, which are implicated in viral replication and transcription. The contrary is true for the envelope glycoproteins: In three of four cases, mutations caused partial deletion of the short intracellular domain of the fusion protein, most likely compromising efficient viral budding. Moreover, in the hemagglutinin gene of a strain showing strongly reduced hemadsorption, 20 clustered A to G mutations, resulting in 16 amino acid changes, were detected. This hypermutation might be due to unwinding modification of a part of the MV RNA genome accidentally present in a double-stranded form. Finally, we classified four lytic and seven persistent MV strains on the basis of their sequences. Surprisingly, the four lytic viruses considered belong to the same class. The persistent viruses form more loosely defined groups, which all differ from the vaccine strain Edmonston.

[Experimental measles infection in rodents]

The sensitivity of newborn hamsters to inoculation with the vaccine L-16 strain of measles virus and the Lec strain isolated from a patient with subacute sclerosing panencephalitis as well as the possibility of persistence of these viruses in the animals were studied. Intracerebral inoculation of the L-15 strain was shown to produce in hamsters acute meningoencephalitis leading to death in 85%-100% of cases. Over 30 days after inoculation, the infectious virus, the virus-specific antigen and virus genome were found in the brain. In the brains of the sick animals, all the structural proteins of measles virus with the exception of hemagglutinin were expressed. After inoculation with the Lec strain, the clinical signs of the disease were less manifest, and mortality was 40%. The infectious virus could be detected in the brain up to 20 days postinoculation, the genome, up to 31 days. All the structural proteins of measles virus were expressed in the brains of the inoculated animals. No persistence of L-16 and Lec strains of measles virus could be demonstrated at langer intervals after inoculation (90-180 days) in the brains of hamsters.