M.J. Van Der Maaten

Serologic detection of bovine leukemia virus infection

Abstract After a review of earlier work, an improved technique for the preparation of the antigen used in the agar gel immuno-diffusion test is described.

Use of glycoprotein antigen in the immunodiffusion test for bovine leukemia virus antibodies.

Abstract The agar gel immunodiffusion (AGID) test for detection of bovine leukemia virus (BLV) antibody was modified by substitution of glycoprotein antigen for p 24 , the etherstable, internal viral antigen used in earlier investigations. This modified AGID test was compared with a complement fixation (CF) test that had shown superior sensitivity to the first AGID procedure. Sera from 263 cattle in commercial dairy herds were tested. The glycoprotein AGID test detected BLV antibodies in 171 sera, but the CF test detected only 134 . In monthly examinations of sera from animals in a BLV experimental herd, the AGID test consistently detected more infected cattle. After experimental or natural infection, 14 of 19 cattle seroconverted to both the AGID and CF tests the same month. When antibodies were detected by only one test, it was usually the AGID test. Colostral antibodies in 2 calves from BLV-infected dams were detected longer by the AGID test than by the CF. These results show that the glycoprotein AGID test is more sensitive than the CF test for detection of BLV antibodies in cattle sera. The AGID test also offers distinct advantages in its simplicity and specificity and promises to be a useful tool for the development of BLV control and eradication programs.

Serological evidence of transmission of bovine leukemia virus to chimpanzees

Abstract After the inoculation of eight chimpanzees with cultured bovine leukemia virus all of them developed specific antibodies six to fifteen weeks later, two control chimpanzees — inoculated with Eagles serum free cell culture medium — did not. Virological studies have not yet provided proof that bovine leukemia virus is replicating in, or can be recovered from circulating leukocytes of the inoculated chimpanzees.

Isolation of a herpes-like virus from lymphosarcomatous cattle

Apparently identical herpes-like viruses were isolated from the leukocytes of two lymphosarcomatous cows. The isolates caused syncytial formation in bovine embryonic spleen cell cultures but were structurally and antigenically unrelated to a bovine syncytial virus previously isolated and described byMalmquist et al. (11). Inoculation of the isolates into guinea pigs, rabbits, mice, hamsters and calves failed to reveal any evidence of pathogenicity but the virus was reisolated from three inoculated calves. The isolates were antigenically distinct from infectious bovine rhinotracheitis virus and pseudorabies virus. Neither their relationship to bovine herpes mammillitis virus nor their possible role in the etiology of bovine lymphosarcoma has been ascertained.

Ovarian lesions in heifers exposed to infectious bovine rhinotracheitis virus by non-genital routes on the day after breeding

Twelve heifers were exposed to either a Colorado infectious bovine rhinotracheitis (IBR) virus isolate or an Iowa IBR isolate obtained from a bovine respiratory disease outbreak. All inoculations were made on the day after the heifers had been in estrus and bred by an IBR virus-negative bull. Pairs of heifers were inoculated with each virus isolate intravenously, intramuscularly or exposed by aerosol. The heifers were killed 11-15 days after inoculation and their reproductive tracts and ovaries subjected to virological and pathological study. Virus was isolated from the ovaries of all 4 heifers inoculated intravenously and from 3 of the 4 heifers inoculated intramuscularly, but not from the ovaries of heifers exposed by aerosol. Virus isolations and lesions were, with only 1 exception, confined to the ovary containing the corpus luteum. In ovaries from which IBR virus was isolated, lesions in the corpus luteum ranged from focal necrosis and infiltration of mononuclear cells to diffuse hemorrhage and necrosis. Most of these ovaries also had necrotic follicles and a diffuse mononuclear cell accumulation in the stroma. Lesions were not found in ovaries from which IBR virus was not isolated. It was concluded that lesions are readily induced in the ovaries of post-estrus heifers as a result of hematogenous spread of IBR virus and suggest that the differences in lesion development observed with the 3 routes are related to whether or not a viremia occurred.

Morphological variation of a syncytial virus from lymphosarcomatous and apparently normal cattle

Double-membrane enveloped, endoplasmic reticulum-associated (ERA) viral particles occurred in the cytoplasm of bovine embryonic splenic cell cultures previously infected with bovine syncytial virus (BSV) that had been isolated from lymphosarcomatous and apparently normal cattle. Previously, BSV was seen only in budding forms at the plasma membrane. It is proposed that the double membrane enveloped, ERA viral-like particle is an aberrant form of BSV because: (1) the ERA viral particle had a nucleocapsid morphologically similar to BSV; (2) it was associated with BSV immunofluorescence; (3) it occurred in the same cells and cell cultures as BSV; and (4) it was not demonstrated in cell cultures in the absence of BSV.

Role of the spleen in the pathogenesis of experimentally induced bovine leukemia virus infection

In an extension of a previous pathogenesis study, bone marrow and other tissues from four experimentally inoculated cattle were tested for virus between the 13th and 20th days after experimental inoculation with bovine leukemia virus. BLV was detected in the blood of three, spleen of two, lymph node of two and bone marrow of only one of the inoculated cattle. In additional studies, four splenectomized and two intact control calves were also examined. Two of these calves were splenectomized before BLV inoculation and two after a persistent virus infection had been established. Results indicated that the removal of the spleen affected neither the establishment and persistence of virus infection nor the development and maintenance of serological responses to viral antigens.

Enhancement of rosette formation between sheep erythrocytes and bovine T-lymphocytes by 2-aminoethylisothiouronium bromide and dextran

Abstract A method for the detection of bovine T-lymphocytes involves rosette formation between lymphocytes and sheep erythrocytes treated with both 2-aminoethylisothiouronium bromide (AET) and dextran. The method detects approximately 70% of peripheral blood leukocytes as rosette-forming cells. Evidence that the rosette-forming cells are T-lymphocytes is also presented.