Albert A. Benedict

Direct complement-fixation test for diagnosis of ornithosis in turkeys.

Summary Employing a soluble antigen, complement-fixation reactions were obtained with turkey antiornithosis sera. Antigens consisting of viable allantoic and killed yolk-sac virus suspensions did not show the same degree of activity. The direct complement-fixation reaction was as sensitive as the indirect complement-fixation test; therefore, the use of the direct test for the study and diagnosis of turkey ornithosis was suggested.

Infrared Spectrophotometry as a Means for Identification of Mosquitoes.

Summary Crude aqueous extracts of Culex molestus, Culex quinquefasciatus, and Aedes aegypti adult mosquitoes were identified by infrared spectrophotometry. The most important differences were the relative intensities of the peaks at about 6.95 and 7.2 μ, and the relative depth and shape of the broad band from about 8.6 to 10 μ.

NEWER METHODS FOR DETECTION OF AVIAN ORNITHOSIS

The increased awareness of the public health importance of turkey ornithosis has stimulated re-examination of the methods used for detection of this infection in domestic fowls. The detection of exposure to ornithosis may be considered to have 3 principal objectives: (1) for diagnostic purposes; ( 2 ) to explore the epidemiological facets of the infection chain, which ultimately will lead to (3) the development of control measures. Obviously, definitive diagnosis is made by isolation and identification of the agent and, as evidenced by recent epizootics in turkeys, virus isolation is made frequently and easily. In severe epizootics the appearance of high-titer circulating antibody in a large number of birds can be considered as direct evidence of infection. Diagnosis is also justified by a significant rise in titer when paired serum samples are available. The significance of the presence of a few serologic reactors with low antibody titers among large flocks is not clear. There exist several possibilities that might explain these situations, such as: (1) the sign of initial ornithosis activity in a flock; (2) the residue of ornithosis infection that was originally manifested with or without clinical ornithosis; (3) the presence of a cross-reacting antibody to an organism similar to the bacterium isolated by Volkert and Matthiesen;l and (4) the presence of unknown nonspecific serologic reactions. The control of ornithosis will be aided by the accurate interpretation of the significance of these reactions. Until recently the serologic technique used exclusively for revealing circulating antibody in domestic fowl has been the indirect complement fixation test (ICF) developed by Karrer, Meyer, and Eddie? The complement fixation (CF) test was not applied for such studies since, among other avian sera, Rice3 reported the failure of antipullorum turkey sera to fix complement (C) with S. pullorurn, and Eddie and Francis4 observed fixation a t only low dilutions with a small number of turkey anti-ornithosis sera. The presence of a specific inhibitor, presumably an incomplete-type antibody, was demonstrated in avian noncomplement fixing and thus the ICF was devised for detection of such antibodies?. 5 , It was generally believed, therefore, that turkeys and chickens do not produce the usual CF antibodies, until recent studies showed that detection of turkey CF antibody depended partially upon the type of antigen employed? Moreover, in 1924 Bushnell and Hudson8 reported that chicken antipullorum sera fixed C with homologous antigen, but that this property was destroyed

Actively and passively induced Arthus reactions in the mouse.

Summary 1. Arthus reactions were consistently produced in mice 35 days following sensitization by 3 intraperitoneal injections of BPA in an adjuvant. 2. Male and female mice were equally Arthus-susceptible. 3. Hemophilus pertussis organisms did not enhance Arthus sensitivity under the same conditions in which anaphylactic sensitivity is enhanced. 4. Reverse passive Arthus reactions were not detected in mice injected with 0.02 mg rabbit anti-EaN, whereas minimal reactions were produced in guinea pigs with 0.005 mg anti-EaN. 5. Reverse Arthus reactions of minimal severity were produced with 0.06 and 0.005 mg mouse anti-BPA N in mice and guinea pigs, respectively.

THE STUDY OF VIRUS PREPARATIONS BY INFRARED SPECTROSCOPY

Infrared spectroscopy has been mainly used by the chemist and physicist as a means for identifying and determining the molecular structure of lowmolecular-weight substances. In spite of limitations imposed by instrumentation, biologists have attempted to apply the technique for a variety of purposes. The classification of heterogeneous mixtures of large molecules is one of the most impressive challenges to the inherently low “signal-to-noise” ratios induced by large molecules. Minor molecular alterations, such as the addition or subtraction of carboxyl or methyl groups, are not detectable in specimens of unfractionated tissues and microorganisms. Nevertheless, there is considerable evidence to indicate that biological systems can be studied by infrared and that in certain instances the method can be used for the identification of constituents in mixtures of macromolecules.?-10 The unique spectra obtained with specimens of whole bacteria6 and with virus preparations, for example, can be attributed in most cases to quantitative differences among the major biochemical components rather than to qualitative differences within similar molecular structures. In view of this, the reproducibility of the unique features of the spectra of such materials remains the major basis for taxonomic differentiation. Thus, precise conditions for the preparation of tissues or microorganisms are required to fulfill this criterion. The criteria available for taxonomic arrangement of viruses depend upon host and tissue preference, antigenic structure, hemagglutination phenomena, size, morphological characteristics, and susceptibility to inactivation by physical and chemical agents. In addition, investigations concerned with the biochemical constitution of viruses may lead to a rational method of distinguishing these agents. In view of the doubtful purity of most virus preparations, a t this time, only questionable biochemical data are available for classification purposes. Nevertheless, the application of infrared absorption spectroscopy was suggested.” The initial studies” failed to show the presence of sharp absorption bands, and, in view of the biochemical make-up of viruses, these reported spectra were surprising. A spectrum of a Newcastle disease virus (NDV) preparation showed only minimal absorption in the vibrational region of 1500 to 1700 cm.-’, suggesting that perhaps amide groupswere present, but that the quantities of material analyzed were insufficient to yield major and minor bands. Apparently no effort was made to determine the concentrations required to produce distinctive bands.