Pathomorphologic characterization of CNS damage in monkeys infected with persistent variant of measles virus vaccine strain L-16.

The lesions of CNS were examined in monkeys infected intracerebrally (i.c.) with a variant of measles virus vaccine strain L-16 isolated after prolonged persistence in human cell culture NEr-2. The persisting virus variant appeared pathogenic for monkeys. The changes which had developed in their CNS within 30 to 60 days post-infection (p.i.) were alike to acute measles encephalitis which was evidenced by giant cell formation at the injection site. Twenty-two months p.i. the chronic character of lesions was evident from the appearance of foci of neuron destruction. Based on morphologic findings it was suggested that strain L-16-H has acquired some properties characteristic of nonattenuated virus.

[Comparative study of the sensitivity of the serological methods used in detecting mumps virus antibodies]. / Sravnitel'noe issledovanie chuvstvitel'nosti serologicheskikh metodov, ispol'zuemykh dlia vyiavleniia antitel k virusu parotita.

Six different methods were used for examinations for the presence of antibodies to mumps virus in 43 sera of donors varying in ages from 18 to 58 years. Judging by the percentage of positive results, most sensitive tests included: radial hemolysis (95.3), neutralization (88.4-81.4), immunofluorescence (83.7). Comparison of the results obtained in these tests revealed high correlation coefficients of antibody titres. The lowest number of positive results was obtained in lectin-neuraminidase test and hemagglutination-inhibition test (51.2% and 32.6%, respectively).

[Clinico-laboratory and seroepidemiological examinations of children immunized with live measles vaccine prepared from genetically homogeneous strain Moscow-5]. / Kliniko-laboratornye i seroepidemiologicheskie issledovaniia privitykh zhivoi korevoi vaktsinoi iz geneticheski odnorodnogo shtamma Moskva-5.

The results of the clinico-laboratory and epidemiological study of a newly developed live measles vaccine obtained from strain Moscow-5, genetically homogeneous and cloned from strain JI-16, are presented. The data indicate that the vaccine obtained from strain Moscow-5 is safe and possesses low reactogenicity and high immunological potency, thus meeting all requirements for vaccinal preparations.

[Comparative characteristics of the physicochemical properties of the vaccinal strain of measles virus L-16 and its Moscow-5 clone]. / Sravnitel'naka kharakteristika fiziko-khimicheskikh svoistv vaktsinogo shtamma L-16 virusa kory i ego klona Moskva-5.

Certain physical and chemical properties of the measles virus vaccine strain L-16 and its clonal variant M-5 proposed as a duplicate of the vaccine strain were studied. The buoyant density of both viruses in sucrose was 1.18-1.19 g/cm3. Virions were found to contain 6 structural proteins. Electron microscopic examinations revealed no differences in the morphology of virions of the vaccine L-16 strain and M-5 clone.

Effect of immunosuppression on morphological changes in CNS of monkeys infected with different measles virus vaccine strains.

Residual neurovirulence of measles virus vaccine strains "Leningrad-16", "Moscow-5" and of cloned variant of L-16 strain--clone 3, differing in the degree of attenuation, was studied in intracerebrally (i.c.) infected Cercopithecus aethiops monkeys, receiving cortisone and/or antilymphocyte serum (ALS). Whereas the sensitivity for detection of the potential neurovirulence of vaccine strains was not increased by cortisone treatment. ALS had such effect in detection of neurotropic properties of the L-16 strain and its cloned variants.

[Use of DEAE-Sephadex A-50 microcarriers for reproduction of the mumps virus]. / Ispol'zovanie mikronositelee DEAE-Sefadeks A-50 dlia reproduktsii virusa parotita.

Reproduction of the vaccine L-3 strains of mumps virus was studied in cultures of continuous Vero cells and in primary cultures of Japanese quail embryos (JQE) growing on DEAE-Sephadex A-50 microcarriers. The Vero cell culture multiplies actively on the microcarrier surface giving more than a 20-fold increase in 8 days. Mumps virus showed a high reproductive capacity in Vero cell culture and in primary JQE cells. Mumps virus-infected Vero cells produce 5-6 pools of virus-containing material with a mean infectious titre 8.2-8.3 lg HAE50/ml. The primary JQE culture infected with mumps virus can yield 2-3 pools of virus-containing material. The intensity of mumps virus replication in the latter directly depends on the multiplicity of infection. Hemadsorption test could be performed in mumps virus-infected cell cultures on microcarriers.

[Persistence of the measles antigen in the central nervous system of monkeys infected with clonal variants of the L-16 vaccinal strain of the measles virus]. / Izuchenie persistentsii korevogo antigena v tsentral'noi nervnoi sisteme obez'ian pri infitsirovanii klonovymi variantami vaktsinnogo shtamma L-16 virusa kori.

The time of persistence of measles antigen was studied in Macaca mulatta and green monkeys inoculated intracerebrally with the vaccine L-16 strain of measles virus and its two genetically homologous variants. Two clones differing in their neurovirulence were used. The results of the study showed correlation between the time of the antigen persistence in the central nervous system and the severity of morphological changes.

Morphological characterisitcs of the pathological process in the central nervous system of monkeys infected with variants of measles virus strain L-16.

The neurovirulence of L-16 vaccine measles virus strains and its 9 clonal variants was investigated in intracerebrally infected Macaca mulatta monkeys. Two groups of clones were distinguished: one comprised variants that caused destructive changes of neurons in the brain and diffuse proliferative gliosis, and the second variants that caused changes of a transitory character, connected with the traumatic exposure.

Genetic characteristics of clones derived from measles virus strain L-16.

The L-16 vaccine strain of measles virus produced in L-41 cell cultures of various size (0.5-0.2 mm in diameter), with clear or opaque centers, thus being genetically heterogeneous by the S and P markes. The clones derived from the L-16 strain differed from it and from each other in a number of genetic properties. Clones isolated at different temperatures, 35 degrees or 32 degrees C, differed from each other in thermostability, sensitivity to interferon, interferon-inducing activity, antigenicity and plaque size. Marked correlations were established between cytopathic activity (TC) and reproductive activity in L-41 cell cultures; thermostability at 50 degrees C (T50 character) and inactivation constant; and interferon-inducing activity and sensitivity to interferon.

[Results of a study of live mumps vaccine from strain L-3 produced by the Moscow research institute for viral preparations. Characteristics of the vaccine]. / Rezul'taty izucheniia zhivoi parotitnoi vaktsiny iz shtamma L-3 proizvodstva Moskovskogo nauchno-issledovatel'skogo instituta virusnykh preparatov. Kharakteristika vaktsiny

For some years the Moscow Research Institute of Virus Preparations carried out studies concerned with the elaboration of conditions for production and control of mumps vaccine from the Leningrad-3 (L-3) strain under experimental production conditions. Twenty nine batches of the vaccine were prepared, tested and studied in extensive field trials. The paper presents the optimal conditions for the preparation of the live mumps vaccine from the L-3 strain in Japanese quail embryo cell cultures. In monkey experiments the L-3 strain was shown to have no neurovirulence. The system of biological control for the mumps vaccine permits to release the preparation meeting the current requirements for safety of live tissue culture parenteral vaccines. The data on the stability of the mumps vaccine from the L-3 strain are presented.