Characterization of a feline infectious peritonitis virus isolate.

A virus isolated in cell culture from the spleen of a cat with feline infectious peritonitis was identified by physicochemical, morphological and antigenic criteria as a coronavirus. The feline infectious peritonitis virus was compared in vitro with canine coronavirus, a reported enteric pathogen of dogs. The feline isolate was characterized, by chloroform sensitivity and resistance to 5-iododeoxyuridine, respectively, as containing essential lipid and an RNA genome.

Fetal infection with bovine leukemia virus in sheep.

Several sheep fetuses were thymectomized, and their tails were removed at 58 to 65 days of gestation for tissue culture. Bovine leukemia virus (BLV) antigens were detected in serial culture of tissues from fetuses whose dams and sires were both BLV positive. However, no BLV antigens were detected in serial cultures of tissues from fetuses whose dams were negative but whose sire was positive.

B-lymphocytes and T-lymphocytes in three types of bovine lymphosarcoma.

Lymphoid cells of peripheral blood, lymph nodes, and thymus from clinically normal cattle, cattle infected with bovine leukemia virus (BLV), and cattle with lymphosarcoma were characterized for T- and B-cell surface markers. B-cells were detected by the erythrocyte-antibody-complement (EAC) rosette test and the surface immunoglobulin (sig) immunofluorescence assay. Peripheral blood from BLV-infected cattle had a higher than normal percentage of B-cells by both EAC rosette and sig immunofluorescence assays.

Concanavalin A and the production of bovine leukemia virus antigen in short-term lymphocyte cultures.

The influence of the mitogen concanavalin A (Con A) on the production of bovine leukemia virus (BLV) antigen in short-term lymphocyte cultures was determined by means of a single radial immunodiffusion test. Con A did not affect viral antigen production in peripheral blood lymphocytes from 60% of both experimentally and naturally infected cattle. Antigen production was stimulated by Con A in lymphocytes from 28% of the cattle, but it was inhibited in lymphocytes from 12%.

Effect of pasteurization and heat treatment on bovine leukemia virus.

Four sheep inoculated with mixtures of bovine leukemia virus (BLV) and milk that was treated by a simulated high-temperature short-time pasteurization procedure did not become infected with BLV or develop tumor. Four sheep inoculated with unpasteurized BLV-mil mixtures became infected with BLV and 3 died with tumor at 15, 21, and 27 months, respectively, after inoculation. Fluid from a BLV-infected cell culture was heated to 56, 60, 65, and 73 C for 1/2 minute and 1 minute (in separate trials) and transferred to noninfected cells.

Pathology of lymphosarcoma in sheep induced with bovine leukemia virus.

Sixty-nine sheep were infected with bovine leukemia virus from bovine lymphosarcoma materials. Twenty-four developed lymphosarcoma and died from 13 to 66 (average, 29) months later. Circulating lymphocytes were increased to leukemia levels (70,000 to 403,000/cu mm blood) in only eight sheep within 2 to 3 months of death.

Lack of infectivity of bovine leukemia (C-type) virus to rats.

Sprague-Dawley rats were given ip injections of bovine culture and sheep cultures of bovine leukemia virus (BLV) and Gross passage-A leukemia virus [MuLV(G)]. Sera were tested to BLV antigens. BLV did not induce tumors in Sprague-Dawley rats, but the rats were susceptible to MuLV(G) at low doses.

An ether-sensitive antigen associated with bovine leukemia virus infection.

An ether-sensitive antigen (es-Ag) associated with bovine leukemia virus infection was detected by immunodiffusion tests. This antigen was sensitive to ether, sodium periodate, and trypsin treatment. Based on column chromatography, es-Ag was a larger molecule than that of ether-resistant antigen (gs-Ag).

Inhibition of bovine leukemia virus release.

Sera from 3 cows with the adult form of lymphosarcoma inhibited release of leukemia virus from a cell line of fetal lamb spleen infected with bovine leukemia virus (BLV). Sera from 5 to 7 cattle experimentally infected with BLV also suppressed virus release. The inhibition of virus release was reversible.

Survey for antibodies to leukemia (C-type) virus in cattle.

Serums from 4,394 dairy cattle in 100 herds and from 2,794 beef cattle in 50 herds were tested for antibody to the bovine (C-type) leukemia virus (BLV), using the agar gel immunodiffusion test. Reactors were found in 66% of the dairy herds (10.2% of the cattle) and in 14% of the beef herds (1.