[Intrathecal synthesis pattern of immunoglobulins in meningoencephalitis epidemic due to echovirus 9]

INTRODUCTION

Epidemics of meningoencephalitis due to echovirus 9 were commonly occurred when a children population become susceptible for the first time in front the virus.

OBJECTIVE

To present the intrathecal synthesis pattern of immunoglobulins of the epidemic that affected Cuba in 1999 and to probe the usefulness of reibergram and antibody index in the diagnostic and characterization of the outbreak.

PATIENTS AND METHODS

23 pediatric patients suffering from viral meningoencephalitis due to echovirus 9 were studied in the income moment. Serum and cerebrospinal fluid IgA, IgM, IgG, albumin and glucose were quantified. Cerebrospinal fluid total protein content and lactate were quantified. Titles of antibodies against echo 9 and Coxsackie A9 and differential cell count were performed.

RESULTS

A mean of 555 cells/10 6 L mainly lymphocytes were obtained. Glucose in cerebrospinal fluid was over 50%, serum glucose and lactate levels below 2.1 mmol/L. In the reibergram an absence of intrathecal synthesis was predominant (15/23), IgM synthesis (6/23) and IgM+IgA (2/23). Blood cerebrospinal fluid dysfunction was observed in 15 patients. The mean antibody index was 1,8 for echo 9 and 0,9 for Coxsackie A9.

CONCLUSIONS

The intrathecal synthesis pattern of immunoglobulins was different from other enterovirus and from echovirus 9 in non epidemic situations before this epidemic, probably with alteration of viral genome.

Acute onset of type I diabetes mellitus after severe echovirus 9 infection: putative pathogenic pathways

Enterovirus infections have been implicated in the development of type I diabetes mellitus. They may cause beta cell destruction either by cytolytic infection in the pancreas or indirectly by contributing to autoimmune reactivity. We sought evidence for these 2 mechanisms in a case of acute-onset diabetes mellitus that occurred during severe echovirus 9 infection. The virus was isolated and administered to cultured human beta cells. No viral proliferation was observed, and no beta cell death was induced, while parallel exposure to Coxsackie B virus serotype 3 resulted in viral proliferation and massive beta cell death. Although the viral protein 2C exhibited a sequence similar to that of the beta cell autoantigen glutamic acid decarboxylase (GAD(65)), no cross-reactive T cell responses were detected. The patient did not develop antibodies to GAD(65) either. Absence of evidence for direct cytolytic action or an indirect effect through molecular mimicry with GAD(65) in the present case raises the possibility of another indirect pathway through which enteroviruses can cause diabetes mellitus.

Nucleotide sequencing of a part of the 5'-noncoding region of echovirus type 9 and rapid virus detection during the acute phase of aseptic meningitis

A part of the 5'-noncoding region of echovirus type 9 isolates was sequenced, and an attempt was made for rapid virus detection in clinical samples obtained from 22 subjects hospitalized with aseptic meningitis. The sequence identity of 440-bp products amplified from the region by RT-PCR was 87.7% between the standard echovirus type 9(Hill strain) and the isolates. Specific IgM antibodies to Hill strain were positive in 45.5% by immunofluorescent antibody staining of virus-infected cells. A high detection rate of PCR products was observed in cerebrospinal fluids (CSFs; 54.5%) at admission, and in peripheral mononuclear cells (PMCs; 72.7%) at the end of hospitalization. Viral genomes were detectable for 2 days in serum samples, and for 6 days in PMC samples after onset of disease. When specific IgM antibody titers were less than 1:40, the amplification rate of viral genome from serum samples was 50.0%. These results indicate that the combination of specific IgM determination and viral genome amplification from CSFs will be a rapid and reliable method for early diagnosis.

Biochemistry and pathogenicity of echovirus 9. II. Mutants of echovirus 9, strain Hill, with altered capsid surface properties

The two echovirus 9 strains Hill and Barty have been shown previously not only to differ in pathogenicity for newborn mice but also in a number of in vitro characteristics which depend on viral capsid structure. Three spontaneously occurring mutants of the mouse-apathogenic echovirus 9 prototype strain Hill being resistant to an inhibitor of plaque formation present in agar were isolated and compared biochemically and biophysically to their parent strain and to the mouse-pathogenic echovirus 9 strain Barty, which is resistant to this inhibitor. The mutants differ from their apathogenic parent strain Hill in most of the same in vitro characteristics as strain Barty, namely adsorption to cells in culture, sedimentation behavior in low salt sucrose gradients, distribution of mutant virus particles in isoelectric focusing, and antigenic determinants inducing neutralizing antibodies. For two of the three mutants, Ag2 and Ag3, evidence was obtained from fingerprinting that they differ from their parent strain Hill in VP1; thus, the observed in vitro properties may be caused by the change in this capsid protein. All mutants, however, were found to be apathogenic for newborn mice and do not replicate in the tissues of these animals. It is concluded that the observed changes in capsid structure do not covary with virulence.

[Sensitive virologic evaluation in suspected meningitis: study of a radioimmunotest for the detection of IgM antibodies against ECHO 9 and ECHO 11 viruses]

The majority of viral meningitis cases is known to be due to ECHO virus infections on one hand, and mumps on the other. While the latter can be diagnosed by IgM antibody detection from one serum sample in the acute stage, diagnosis of enterovirus infections is by virus isolation and typing. An IgM-antibody test for ECHO 9 and 11 viruses is presented to evaluate the possibility of rapid serological diagnosis of ECHO virus meningitis cases. 36 cases from five local outbreaks due to ECHO 6, 9, 11, and 30 viruses were characterized by virus isolation and serum neutralization tests. All sera (88 samples) were assayed by a MACRIA (M-antibody capturing radioimmunoassay) to ECHO 9 and 11 viruses. While sera from all ECHO 9 and 11 cases, when taken at appropriate times, had IgM antibodies to the infecting type, a varying degree of cross-reactivity could be observed. Specificity problems are discussed in comparison with isolated cases of enteroviral infections due to different types, including Coxsackie B viruses.

Selective inhibition of human neutrophilic chemotaxis by echo virus, type 9. Virus-induced changes in membrane fluidity

By means of the excimer-forming lipid technique changes of membrane fluidity of human PMNs exposed to a chemoattractant (FMLP) and/or Echo virus, type 9, strain A. Barty has been investigated. It was shown that preincubation of PMNs with Echo 9 virus results in a viral dose-dependent decrease of membrane fluidity of granulocytes exposed to FMLP. The virus-induced rigidity of cell membrane causes obviously a disturbance in the aggregation of membrane particles to form receptors, and thus can lead to a failure of regular processing of chemotactic signals.

Selective inhibition of human neutrophil chemotaxis by ECHO-virus, type 9

Preincubation (37 degrees C, 60 min) of human neutrophilic granulocytes with various concentrations of infectious ECHO virus, type 9, strain A. Barty resulted in virus-dose dependent inhibition of neutrophil chemotactic reactivity (Boyden-chamber assay) to chemoattractants (F-Met-Leu-Phen: zymosan-activated human serum). Other cellular functions-phagocytosis, increase of oxidative cell metabolism, intracellular killing of live staphylococci--remained intact. This selective inhibition of human neutrophilic chemotaxis was due to viral induced cytotoxicity or competitive inhibition of chemotactic cell surface receptors.

[Persistence of latex-agglutination inhibiting and neutralizing antibodies against enterovirus in the healthy population (author's transl)]

Sera of 122 persons were examined by the neutralization and latex-agglutination inhibition tests for antibodies against Polio type I, Coxsackie virus type A 9 and B 4, as well as Echo virus type 9. With increasing age there was a titre difference between latex-agglutination inhibiting and neutralizing antibodies, due to the earlier fall in the former. These antibodies, contrary to neutralizing ones, were in the lower titre region. The results confirmed the usefulness of the latex-agglutination inhibition test in the diagnosis of acute enterovirus infections.