Radioimmunoassay for intact Gross mouse leukemia virus.

Abstract

A radioimmunoassay for intact Gross leukemia virus has been developed using 2RI-labeled Gross virus grown in tissue culture and guinea pig antisera to Gross virus grown either in tissue culture or harvested from leukemic C3H(f) mice. Separation of bound from free labeled virus was effected using the double antibody method. The assay can detect fewer than 108 virus particles and has been used to measure the viral content of individual organs from inoculated leukemic C3H(t) mice and from Ak mice with spontaneous leukemia. Organs from noninoculated healthy C3H(f) mice crossreacted poorly in the system, virus generally being detectable only in the thymus-and spleen and at low concentration. In some of the inoculated C3H(f) leukemic mice the viral content of as little as 0.5 p1 of plasma is measurable. That this assay is for intact virus and not for soluble antigens of the viral envelope was proven by the observation that the immunoreactive material of plasma and extracts from thymus and liver of leukemic mice has a buoyant density in sucrose of 1.17-1.18 g/ml, corresponding to that of intact virus grown in tissue culture. With this sensitivity it may now be possible to quantitate viral concentrations in tissue and body fluids from the time of inoculation through the development of obvious pathology.Since its application to the measurement of plasma insulin in man (1, 2), radioimmunoassay (RIA) has increasingly become the method of choice for the determination of the concentration of peptidal and nonpeptidal hormones and nonhormonal substances of medical and biological interest in plasma and tissue (see ref. 3 for review). RIA was applied to a viral antigen for the determination of circulating hepatitis B antigen and its antibody (4, 5). Since then there has been increasing interest in the application of this methodology in a variety of investigations in virology. Most of these have been concerned with the development of sensitive radioimmunoassays for the protein components of RNA C-type oncogenic viruses, i.e., the core proteins from mammalian (6-13) and avian species (14) (generally less than 30,000 daltons) and mammalian membrane glycopeptides (about 70,000 daltons) (13), which appear to be elements of the viral envelope. Some (15, 16) have been developed for the assay of intact mouse mammary tumor virus. In this report we describe an RIA for intact Gross murine leukemia virus and its application to the measurement of the virus content of plasma and individual organs of normal, noninoculated, nonleukemic C3H(f) mice and of inoculated leukemic C3H(f) mice and of Ak mice with spontaneous leukemia. MATERIALS AND METHODS AnimalsMice of the C3H(f) inbred line raised by brother-to-sister mating in our laboratory were employed. Ak mice from our colony were also studied after the development of spontaneous leukemia. Rats of the Sprague-Dawley strain, bred in our laboratory by brother-to-sister mating, were used for serial propagation of the Gross mouse leukemia virus adapted to rats.

Relative loss of oncogenic potency of mouse leukemia virus (Gross) after prolonged propagation in tissue culture.

“…3), indistinguishable from those previp9s de-scribed in virus-induced mouse leukemia (9, 10), were o on electron microscopic examination in organs of mice that developed leukemia after inoculation of the tissue-culturepassaged virus. The number of virus particles observed in leukemic tissues was also comparable to that observed in organs of mice or rats with leukemia induced with passage A (Gross) mouse leukemia virus (7,10). Lack of Resistance of Mice Inoculated with Tissue-Culture-Grown Virus to Subsequent Challenge with MousePassaged Virus.…”

Advances in rapid point-of-care virus testing

“…Yalow et al reported a radioimmunoassay method for the detection of complete mouse leukemia virus in mouse plasma and single organs. 64 Using the Guinea pig antiserum obtained in tissue culture, they separated the conjugates from the free labeled virus by the double antibody method, and established a complete radioimmunoassay method of intact gross leukemia virus. This method is very sensitive – the detection limit is less than 108 virus particles, so it is possible to quantitatively determine the virus concentration in tissues and body fluids from the time of inoculation through an obvious pathological process.…”

Radioimmunoassay: a probe for the fine structure of biologic systems

“…60] has become the method of ehoiee for testing for infected blood in Red Cross and other blood banks in the United States where transfusion-transmitted hepatitis has been a significant public health problem. The recent description of an RIA for intact murine leukaemia virus [61], with sutlicienl sensitivity to delect virus in 0.5 n\ of blood or of lissue extracts from animals with viral induced or spontaneous leukaemia, gives us a tool with which we may be able to determine where and in what concentration a virus resides during the period from infection to the time when the fully developed pathologic manifestations of the disease are present. Recently we have developed a sensitive and specific RIA for some constituent of tubereulin purified protein derivative (PPD) [62] which is shed into culture medium in vitro or in vivo by growing Mycohacterium tuhercutosis.…”