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Biomedical subjects

K F Meyer

Publications and source records attributed to K F Meyer.

At least 37 records · Page 2Linked to original sources
PubMed1973

Pathogenicity and immunogenic efficacy of a live attentuated plaque vaccine in vervet monkeys.

A live attenuated Yersinia pestis (Pasteurella pestis) vaccine strain designated EV51f, which had been passaged through guinea pigs previously treated with ferrous sulfate, was shown to be pathogenic for African green vervet monkeys (Cercopithecus aethips pygerythrus), but not for guinea pigs. The bacilli multiplied in the monkeys, as shown by positive blood cultures, caused an elevation of white cell counts and rectal temperatures, and resulted in death of 26% (13/50) of animals. Postmortem findings of these animals were typical of bubonic-septicemic plague. This vaccine did not cause deaths in 50 guinea pigs even in doses up to 100 million viable bacilli inoculated subcutaneously. It is suggested that the virulence of an attenuated Y. pestis strain which does not produce pigment on a defined medium containing hemin, but possesses all other known virulence determinants, is dependent on the availability of iron in vivo. The serological response of the monkeys as determined by the hemagglutinating and mouse protective antibodies was high one month after vaccination and also in guinea pigs, as shown by virulent challenge. This antibody level declined in monkeys over a period of nearly 6 months, and a decline in immunity was confirmed by virulent challenge which resulted in the death of 30% of vaccinated monkeys. The level of immunity in monkeys did not appear to be related to the dose of vaccine.

Animals↗
PubMed1970

Plaque formation by Chlamydia in L cells.

Chlamydiae were found capable of producing plaques in several cell lines. Mouse fibroblast cells, L-929, proved the most sensitive to infection and yielded plaques of the highest clarity. Assay of chlamydial infectivity by plaque titration was at least as sensitive as egg ld(50) determination. Among chlamydial isolates of avian, mammalian, and human origin, only slow-growing trachoma-inclusion-conjunctivitis agents did not produce plaques. The plaque assay is highly sensitive, reproducible, and offers a potential tool for investigations requiring accurate measurement of small changes in chlamydial infectivity.

Journal Article↗
PubMed1970

Plaque reduction technique for demonstrating neutralizing antibodies for Chlamydia.

Some members of the genus Chlamydia (Bedsonia or psittacosis-lymphogranuloma venereum-trachoma-inclusion conjunctivitis group of microorganisms) produce plaques in monolayers of mouse fibroblast (L-929) cells. Hyperimmune chicken antisera may be capable of specifically reducing plaque counts. When the test was applied to chlamydiae isolated from avian species, the results indicated that different isolates with a common source had similar antigenic reactivity. The plaque reduction test is a potentially useful method for serotyping chlamydiae. The difficult aspect of the method appears to be a readily reproducible means of producing neutralizing antiserum.

Journal Article↗
PubMed1970

Effectiveness of live or killed plague vaccines in man.

While the safety of the available live plague vaccine EV 76 (Paris) continues to be the subject of further study, the USP formol-killed, virulent Pasteurella pestis (Yersinia pestis) suspension capable of protecting 60% of non-human primates, particularly Hanuman langurs (Presbytis entellus), warrants further clinical tests and field trials. Inoculated in a dosage of 2x10(9) killed plague bacilli (1 ml), followed by a booster of 400 million organisms (0.2 ml) in 1-3 months, this vaccine stimulates the appearance of passive mouse-protection antibodies (below an index of 10) and passive haemagglutinins in 60%-65% of human subjects. Recent experiences in Viet-Nam demonstrate that personnel vaccinated with the USP vaccine, although frequently exposed, enjoy almost complete freedom from the disease. One of the 4 known and confirmed cases of bubonic plague in North Americans occurred in an unvaccinated individual. Among individuals inoculated with the USP vaccine, 2 confirmed cases of pneumonic plague and 1 case of asymptomatic pharyngeal plague have been recorded. The incidence of plague in the Republic of Viet-Nam during the past 3 years is estimated at 13 263 cases in a population in part vaccinated with a live plague which exhibited inadequate immunogenic efficacy in experimental tests.

Animals↗
PubMed1969

Lymphogranuloma venereum. II. Characterization of some recently isolated strains.

Five Bedsonia (Chlamydia) isolates from lymphogranuloma venereum (LGV) patients were tested for inclusion type, sulfonamide sensitivity, and mouse virulence. Two matched the classical description of LGV agents. Two were not virulent for mice by the intracerebral route, therefore fitting the description for trachoma-inclusion conjunctivitis agents. One was highly virulent for mice and sulfonamide-resistant, and produced inclusions that did not stain with iodine, all characteristics generally associated with avian bedsoniae. A sixth isolate could not be adequately tested due to poor infective yields. Because of this variety of properties within the Bedsonia group, the term LGV might more appropriately be reserved for clinical disease rather than to describe a particular bedsonial agent.

Animals↗
PubMed1968

A serological survey of rodent plague in Taiwan and offshore islands.

Serological surveys were made on individual sera of small animals trapped on Taiwan and offshore islands. The animals were shrews of the species Suncus murinus, and rats of the species Rattus rattus and R. norvegicus. The tests showed that on MaKung in the Peng-hu Islands (Pescadores), 66% of the shrews, 30% of the R. rattus and 15% of the R. norvegicus had passive haemagglutination titres with fraction 1 antigens in the range of 1:16 to 1:256, indicative of previous plague infections. These observations supplement recent findings in Viet-Nam and confirm that plague is endemic not only in rats but also is shrews in the coastal provinces of South China.

Animals↗