John D. Marshall

Superiority of fluorescein isothiocyanate (Riggs) for fluorescent-antibody technic with a modification of its application.

Summary 1) The globulin fractions of antisera representing bacterial, viral, mycotic agents and antiglobulin fractions were labeled with 2 derivatives of fluorescein amine by 3 methods. 2) Fluorescein isothiocyanate was shown to be superior in stability, ease of conjugation, and degree of fluorescence. This direct method of adding the dye to a dilute buffered antiserum eliminates the need for organic reagents which may denature the protein.

BEAK AND FEATHER DYSTROPHY IN WILD SULPHUR-CRESTED COCKATOOS (CACATUA GALERITA)

Three flocks of wild sulphur-crested cockatoos in southeastern Australia had a 10– 20% prevalence of feather and beak deformities. In affected birds, the crest, tail, contour and down feathers were lost or reduced in length owing to a “pinching off” 0.5–1 cm above the skin. The underlying skin was discolored brown. Flight feathers appeared normal and could sustain flight. In mildly affected birds, only the crest and down feathers were involved. Histological examination of affected feathers showed necrosis of developing cells in their epidermal collars. The epidermis was moderately hyperplastic and contained numerous large macrophages, with large intracytoplasmic granules. Electron microscopic examination showed these granules to consist of regular lattices of 17–20-nm-diameter particles, resembling parvovirus particles. In some birds the upper beak was enlarged and had longitudinal cracks. Histological examination of the beak showed necrosis of its epidermis. It was concluded that a viral infection may have caused feather and beak dystrophy in these birds.

The influence of climate on the seasonal prevalence of plague in the Republic of Vietnam.

An 8 year study of the influence of climate on the seasonal prevalence of bubonic plague in the Republic of Vietnam has been completed. Climatic conditions were found to influence the course of plague epidemics in 2 ways: 1) by regulating the density of the flea population; and, 2) by regulating the efficiency of Xenopsylla cheopis in transmitting the plague bacillus. Slight variations in temperature, relative humidity, and vapor pressure deficits either permit an epidemic to flourish or cause a decline in its intensity.

Use of Contrasting Fluorescent Dye as Counterstain in Fixed Tissue Preparations

Summary A counterstaining method is described that gives a contrasting reddish-orange background when used with fluorescein-labeled antibody systems. It curtails non-specific fluorescence in tissues and tissue cultures. The possibility of a nonspecific protein-protein reaction is discussed. This reaction apparently plays no part in the serological system to which it has been added.

SUSCEPTIBILITY OF RODENTS TO ORAL PLAGUE INFECTION: A MECHANISM FOR THE PERSISTENCE OF PLAGUE IN INTER-EPIDEMIC PERIODS

Oral infection of rodents with Pasteurella pestis has been demonstrated with both fully virulent and avirulent strains. Sustained rodent plague epizootics have been initiated and maintained in the absence of the classical flea vector. Transmission was due to cannibalism of the dying rodents by their healthy cagemates. Oral infection is considered to provide a plausible mechanism for the persistence of plague in an area where conditions are temporarily unsuitable for flea transmission.

Identification of Listeria monocytogenes by the Fluorescent Antibody Technic

Summary Preparation is described of a polyvalent somatic fluorescein labeled antiserum which was specific for 30 strains of Listeria tested but did not react with 180 heterologous strains. Preparation and specificity of flagellar and whole cell antigens are discussed as well as some technical implications of fluorescent antibody technic.

Serological Response of Rhesus Monkeys (Macaca mulatta) to Immunization and Infection with Pasteurella pestis

Summary Living attenuated Pasteurella pestis vaccine EV76(51f) was an effective immunizing agent for Macaca mulatta by either the oral or parenteral route. As determined by serological tests and challenge experiments, a killed plague vaccine was less effective.

Clostridium perfringens iota antitoxin levels in convalescent sera from hemorrhagic fever patients.

Summary Sera from 17 patients convalescing from hemorrhagic fever and 50 normal controls were tested for the presence of neutralizing antibodies of Cl. perfringens iota toxin. Hemorrhagic fever sera contained a significantly higher quantity of neutralizing antibodies than did the control sera.