Characterization of IM virus, which is frequently isolated from cerebrospinal fluid of patients with multiple sclerosis and other chronic diseases of the central nervous system

Seroepidemiology of Inoue-Melnick virus in the general population of Buffalo, New York

The prevalence of antibodies to Inoue-Melnick virus (IMV) types 1 and 2 in the general population of Buffalo, New York, was studied. Serum specimens were collected from blood donors, and pediatric sera were provided from the Buffalo Children's Hospital. Neutralizing antibody titers against IMV were measured with established procedures. Very high prevalence of antibodies to both IMV types 1 and 2 were found in sera from children of Buffalo, especially in the age group 15-19 years (nearly 100%). The antibody positivity gradually decreased with advancing age, except for the groups of age 60 and older. This is in sharp contrast to a previous report examining sera from the people of Osaka, Japan, in which IMV antibody was not found in children under 10 years of age. In the group of teenagers in Buffalo, with high geometric mean antibody titers, an association with any disease was not found. The peculiar distribution of antibodies to IMV was considered to be possibly related to the high incidence of multiple sclerosis (MS) in the Buffalo area, in contrast to the data from Osaka, Japan, which is a low incidence area for MS.

Isolation of Inoue-Melnick virus from colorectal carcinoma tissues

BACKGROUND

Isolation of Inoue-Melnick virus (IMV) Type 1 from tumor tissues of patients with colorectal carcinoma in Japan was reported. A high prevalence of IMV antibodies has been found among patients with colorectal carcinoma in Buffalo, New York.

METHODS

IMV was isolated from homogenates of colorectal carcinoma and other tissues, inoculated into MRC-5 human fibroblast cultures. IMV-specific cytopathic effects were detected and titrated following 7 days of incubation in a roller-tube apparatus.

RESULTS

IMV was isolated from all nine (100%) colorectal carcinoma tissues tested and all four (100%) normal parts of colon mucosa tissues obtained from patients with cancer. Biopsy specimens of normal colon mucosa from 10 patients without colon carcinoma were negative for IMV (0%). Average infectious titers of IMV in these tissue homogenates were 4.41 for tumor tissue and 2.55 log10 tissue culture infectious dose by 50% (TCID50)/0.1 ml for colon mucosa, respectively. Most of the isolates were the IMV intermediate type.

CONCLUSIONS

Our results confirmed the production of infectious IMV in colorectal carcinoma tissues, as reported recently in Japan. The role of IMV in colorectal carcinogenesis is currently unknown.

Preliminary characterization of a new virus isolated from the spinal fluid of patients with meningitis in São Paulo, Brazil

A total of 138 patients with the age of 4 months to 57 years were attended in different hospitals of São Paulo State with aseptic meningitis. A probable new agent was isolated from the cerebrospinal fluid of 35 of 53 specimens examined. Replication of the agent with similar characteristics was detected by CPE produced in the MDCK cell line. Virus-like particles measuring about 40 nm in diameter were observed by negative staining electron microscopy. No hemagglutinating activity was detected at pH 7.2 by using either human, guinea pig, chicken and at pH ranged 6.0-7.2 with goose red blood cells. The agent was not pathogenic to newborn or adult mice. Virus infectivity as measured by CPE was sensitive to chloroform and not inhibited by BuDR, suggesting that agent is an enveloped virus with RNA genome.

Enhancement of Inoue-Melnick virus synthesis by 5-bromodeoxyuridine in human meningioma (MG-1) cells

The authors found remarkable enhancement of Inoue-Melnick virus (IMV) synthesis by 5-bromodeoxyuridine (BUDR) in human meningioma (MG-1) cells, a virus-producer line of type 1 IMV. Treatment with BUDR resulted in rapid and abundant synthesis of infectious IMV in MG-1 cells. The titer of the cell-associated virus in treated cells increased approximately 6.0 log 10 compared with that in untreated cells. Immunofluorescent antibody tests revealed that IMV-associated late antigen was induced by BUDR in the cytoplasm of approximately 50% of treated cells. A clonal difference was also found in the enhancement of BUDR on the IMV synthesis in MG-1 cells. The most remarkable enhancing effect of BUDR was observed in the clone C line, and a herpes-type virus was detected by negative-staining electron microscopy in the culture fluid of the clone C treated with BUDR.

Factors influencing the assay of Inoue-Melnick virus

We describe factors influencing the assay of Inoue-Melnick virus (IMV) and practical comments for its assay. MRC-5 cells at a population doubling level (PDL) of more than 32 were more sensitive than younger cells for demonstrating cytopathic effect (CPE) of the virus. The PDL of MRC-5 cells also influenced the virus yield, particularly when the amount of viral inoculum was small. Cells at younger PDL produced less virus. The appearance of CPE and the virus yield were inhibited by increasing the concentration of NaHCO3 to 0.14% in the maintenance medium. The release of the virus into the medium was also inhibited as NaHCO3 was increased.

Thermostabilization of Inoue-Melnick virus by salt

Inoue-Melnick virus (IMV) was stabilized to thermal inactivation at 50 degrees C by 1 M Na2SO4 but not by 1 M MgCl2, 1 M MgSO4, 2 M NaCl, and 2 M KCl. The latter salts enhanced the inactivation over that in distilled water. Na2SO4 stabilized IMV at 1 M concentration but enhanced inactivation at 0.1 M. Three types of IMV were stabilized by 1 M Na2SO4 at 50 degrees C to almost the same degree. The pattern of the thermostabilization of IMV by salts was similar to that of herpes simplex virus; however, the degree of its stabilization was lower with prolonged heating.

Inhibitory effect of acyclovir on the growth of Inoue-Melnick virus isolated from cerebrospinal fluid

Inoue-Melnick virus (IMV) was isolated from the cerebrospinal fluid of patients with chronic neurologic disorders. The effect of acyclovir (ACV), 9-(2-hydroxyethoxymethyl)-guanine, on the growth of IMV was studied in human diploid cell cultures. ACV markedly inhibited the multiplication of all three IMV serotypes in vitro with the same inhibitory effect. By passage of IMV in the presence of ACV in the medium, ACV-resistant mutants of three IMV serotypes were easily isolated.

Persistence of Inoue-Melnick virus and antibody in cerebrospinal fluid

Serial cerebrospinal fluid samples were obtained from 14 multiple sclerosis patients over a period of several months and were tested under code for Inoue-Melnick virus. In five of the positive patients, virus was present in 28 of 32 specimens collected over a period of 2 to 5 months. Four patients, from whom a total of 34 specimens were taken, yielded only a single isolate each. Five patients contributed 28 specimens, all of which were negative. In six patients (three virus positive and three virus negative), neutralizing antibody was detected in serum and in cerebrospinal fluid.

Inhibitory effect of glucocorticoid hormones on the growth of Inoue-Melnick virus

Glucocorticoid hormones inhibited the early stage of propagation of Inoue-Melnick virus in a dose-dependent manner in human diploid cell cultures. Prednisolone and hydrocortisone achieved complete inhibition of replication of the three Inoue-Melnick virus serotypes at concentrations of 0.2 X 10(-4) and 10(-5) M, respectively; strong inhibition was found even at 10(-5) and 10(-6) M, respectively. The steroid hormones did not show a direct effect on the virus.

Isolation of Inoue-Melnick virus and detection of antibodies in coded cerebrospinal fluid specimens from patients with disorders of the central nervous system

Inoue-Melnick virus was isolated from coded cerebrospinal fluid samples from 10 of 25 patients with chronic diseases of the central nervous system. Of 13 multiple sclerosis patients and 12 patients with a variety of other symptoms and signs 4 and 6, respectively, were positive. Replicate samples from the same patient yielded the same results, either positive or negative. Neutralizing antibody was present in cerebrospinal fluid at a dilution of 1:25 in the virus-positive patients. Only a single virus-negative patient was positive for antibody at this dilution.