Persistent measles virus infection in a calf kidney cell line. Note IV. Electron microscopic observations in the K-2 cell line.

An electron microscopic study was performed in the K-2 calf kidney cell line persistently infected with measles virus. Aggregates of granular filamentous structures 20-30 nm in diameter were detected in the paranuclear zone of the cytoplasm. Rare, isolated smooth filaments 15-17 nm in diameter were also observed. No such structures were seen in the nucleus. The budding process was very active. Many pleomorphic particles ranging in diameter from 100 to 600 nm were observed at the cell surface and in the intercellular space; the particles contained a variable amount of filamentous nucleocapsid structures and had an envelope with discontinuous fuzzy material.

Chromosome changes in the leukocytes from patients with subacute sclerosing panencephalitis.

Alterations in chromosome number and structure could be detected in phytohemagglutin-stimulated leukocyte cultures from four patients with an ascertained diagnosis, of subacute sclerosing panencephalitis. Chromosome changes are polymorphous, involving most frequently the acrocentric group G or D chromosomes. It is suggested that chromosome damage might represent a diagnostic indication before the onset of neurologic symptoms.

Isoenzymes of succinate dehydrogenase in measles virus-infected monkey kidney cells.

Succinate dehydrogenase (SDH) isoenzyme patterns were analyzed in R6CA monkey kidney cells inoculated with wild and attenuated measles virus. Cell homogenates were prepared either in a sucrose--Triton X-100 mixture, or in sucrose alone. In both cases the most important SDH isoenzyme pattern alterations were observed in the homogenates of cells infected with wild measles virus at 72 hours post inoculation. Similar alterations occurred in homogenates of cells infected with the attenuated strain after a delay of about 100 hours. In all the experimental variants the use of Triton X-100 allowed the visualization of a larger number of isoenzyme bands.

Persistent measles virus infection in a calf kidney cell line. Note III. Cellular alterations in the selected chronically infected K-2 cell line.

Marked morphological, growth and chromosome alterations pointing to in vitro cellular transformation were made evident in a selected calf kidney cell line (K-2) chronically infected with measles virus. The transformed cell line released infectant virus and had no oncogenic potential for the hamster.

Stability of antimeasles vaccine under the influence of some physical and chemical factors.

A study on the stability of lyophilized and rehydrated measles vaccines under the influence of temperature and light was undertaken. After rehydration there was a considerable decrease in the potency of the vaccine, even when stored at +4 degrees C-- +8 DEGREES C and in the dark. Out of the several drugs tested, the commercially available drug AS was found to have a stabilizing effect on measles vaccine infectivity.

Persistent measles virus infection in a calf kidney cell line. Note II. Study of some biological markers of the measles virus isolated from a selected chronically infected cell line.

The biological characteristics of a measles virus strain (Co-69/pi) isolated from a selected chronically infected calf kidney cell line (K-2) are studied in comparison with those of thw wild parental CO-69 and of the attenuated Schwarz measles virus strain. Co-69/pi is a variant of the parental Co-69 virus and has characteristics of an attenuated strain. Some of the characteristics acquired by the Co-69/pi strain (cytopathogenicity, size of plaques) proved to be stable in the course of passages on a simian substrate. The mechanism having led to the appearance of this variant in the chronically infected cell line are discussed.

Significance of some immunochemical data for the viral pathogeny of multiple sclerosis.

Cerebrospinal fluid (CSF) samples from 124 patients with different neurological diseases (35 having an ascertained diagnosis of multiple sclerosis (MS) and 20--of subacute sclerosing panencephalitis (SSPE)) were investigated by immunoelectrophoresis. The correlation between the "secretory" immunoelectrophoretic pattern of CSF proteins in MS and SSPE patients and the incidence of antimeasles HI antibodies in the CSF is analysed. The results point to a different pathogenic significance of the presence of antimeasles antibodies : a) persistent measles virus infection in SSPE and b) a particular genetic constitution, coincident with a hyperreactivity to measles virus, in MS.

The incidence of antiviral antibodies in multiple slcerosis.

The serological investigation of 96 multiple sclerosis (MS) patients, 61 patients with various other neurological diseases and 100 healthy controls made evident the increased incident of antimeasles and antiparinfluenza type 1 antibodies in the group of "probable" MS patients. There was no significant difference as regards antimumps antibodies. Antimeasles antibodies were detected in 7 of the 8 cerebrospinal fluid samples from "probable" MS patients, but in none of the 12 samples from patients with other neurological diseases. The significance of these results for the etiology of MS is discussed.

Activity of lactate dehydrogenase, acid and alkaline phosphatases in measles virus-infected monkey kidney cell cultures.

The influence of wild (Co-69) and attenuated (L-16) measles virus infection on the activity and activation energy of lactate dehydrogenase (LDH), acid and alkaline phosphatases (P-ase) was tested in R9CA monkey kidney cells at various time intervals after inoculation. With both virus strains significant changes in enzymatic activity occurred especially within the first 24 hours post inoculation. The two stains have a different influence on alkaline P-ase activity variation, which might therefore be used as a differentiation marker. Variations in LDH activation energy might be an early indicator of virus infection. LDH activity is significantly higher in cellular homogenates diluted 1:10, the dilution effect being more obvious in infected cells after a longer time interval post inoculation.

Persistent measles virus infection in a calf kidney cell line. Note I. Establishment of calf kidney cell lines chronically infected with measles virus and some of their biological characteristics.

Several types of persistent measles virus infection resulting in lytic infections could be established in a calf kidney cell line, according to the passage level of the substrate and to the virus strain inoculated. Persistent measles virus infection in calf kidney cells was characterized by the limited proportion of infected cells, the large amount of infectant virus, and the alteration of morphological and growth characteristics of the cells. The mechanism of this persistent infection is discussed.

Investigations of the antiviral activity of some nitroso-urea derivatives. Inhibitory action of the IOB-252 nitroso-urea derivative on vaccinia virus incell cultures.

The nitroso-urea derivative IOB-252 was administrered in monkey kidney cell cultures in a concentration of 40 mug/ml 24 hours before inoculation of vaccinia virus and maintained afterwards in a concentration of 25 mug/ml. The drug inhibited vaccinia virus multiplication, hemagglutinin synthesis and late cytopathic effect, but did not prevent early cytopathic lesions. IOB-252 inhibited the synthesis of interferon initiated by a viral inductor and blocked the antiviral effect of an exogeneous interferon. The mechanism of action of the drug is discussed.

The presence of interferon and type A immunoglobulins in the nasopharyngeal secretions of volunteers immunized with an inactivated influenza vaccine.

The presence of interferon and type A immunoglobulins (IgA) was followed up in the nasopharyngeal washings collected from volunteers immunized intranasally with an inactivated influenza vaccine [strain A/Rom 1/73 (H3N2)]. Interferon was detected 24 hours after vaccine administration, its incidence being similar to that in the course of acute infection. Intranasal administration of inactivated influenza vaccine stimulated the production of secretory IgA in 3 of 10 samples collected 12 days after vaccination. At the same time, IgA were found in 4 samples collected before vaccination, and inhibited in certain cases the stimulation of interferon synthesis. The practical importance of the route of influenza vaccine administration is discussed.