Monoclonal antibodies against Aleutian disease virus distinguish virus strains and differentiate sites of virus replication from sites of viral antigen sequestration

Abstract

Monoclonal antibodies (mAbs) were used to study antigenic differences among strains of Aleutian disease virus (ADV) and to characterize viral proteins in vitro and in vivo. A number of ADV field strains could be discriminated, and highly virulent Utah I ADV was clearly delineated from the tissue culture-adapted avirulent ADV-G strain. This specificity could be demonstrated by indirect immunofluorescence against infected cultures of Crandell feline kidney cells or against tissues of Utah I ADV-infected mink. Viral antigens were demonstrated in both the nuclei and the cytoplasm of infected tissue culture cells. However, in mink mesenteric lymph node, spleen, and liver, viral antigen was observed only in the cytoplasm. Absence of nuclear fluorescence suggested that the detected antigen represented phagocytized viral antigens rather than replicating virus. This conclusion was supported by the finding that mAbs reactive only against low-molecular-weight polypeptides derived from intact viral proteins gave the same pattern of in vivo fluorescence as mAbs with broad reactivity for large or small (or both) viral polypeptides. The distribution of infected cells was the same as that described for macrophages in these tissues and suggested that cells of the reticuloendothelial system had sequestered viral antigens. Aleutian disease (AD) is a parvovirus-induced disease of mink characterized by viral persistence, hypergammaglobulinemia, and immune complex-mediated renal and arterial lesions. Affected mink usually die of terminal glomerulonephritis after a mostly subclinical course lasting weeks, months, or years (6, 12, 18, 22, 29, 31). Immune complexes play a prominent role in the pathogenesis of the renal disease, and although some of the immune complexes contain infectious virus, it is clear that many complexes are too small to contain intact virus (4, 23, 30). Consequently, it is uncertain what viral components actually participate in the generation of immune complexes. Sera from infected animals contain antibody to both structural and nonstructural viral proteins (7). Furthermore, the proteins of AD virus (ADV) seem to be degraded during in vivo infection (3). Thus, a variety of viral proteins could be involved in immune complex development. Furthermore, antibodies to DNA are present in the sera of infected mink, and DNA-anti-DNA complexes may also have a role in the pathogenesis (16, 17). In addition, it is not clear whether virus detected earlier (30) was within cells replicating virus or rather identified cells that had phagocytized viral antigen, and since the reagent used previously to detect virus is polyclonal, it is not clear that only viral components were recognized. The ability to distinguish viral polypeptides immunologically would make it possible to define which viral products were present, both in soluble immune complexes and complexes deposited in tissues. Another major problem in the study of AD has been the difficulty in differentiating virus strains. Although the relative pathogenicity of various ADV i...

Subcellular localization of Aleutian mink disease parvovirus proteins and DNA during permissive infection of Crandell feline kidney cells

“…The intranuclear shells of VP were not resolved in previous studies in which the same anti-VP MAbs were used for immunofluorescence analysis (3,32). The hollow shell structures that are so striking in single confocal optical sections appear more as solid bodies when viewed by epifluorescence.…”

“…The rabbit anti-NS immunoglobulin G (27,31) was conjugated to fluorescein isothiocyanate. A cocktail of murine monoclonal antibodies reactive against both VP1 and VP2 was used to detect ADV VP proteins (32). DNA probes for the detection of ADV DNA were prepared by PCR (29).…”

Antigen Distribution in Organs of Mink with Aleutian Disease Parvovirus Infection

“…According to previous immunohistological findings (PORTER et al, 1969;RACE et al, 1986;HAAS et al, 1990) viral antigen was found in the cytoplasm of Kupffer cells. A prerequisite for the demonstration of viral proteins was to perform an elution procedure on cryosections.…”

Molecular comparisons of in vivo- and in vitro-derived strains of Aleutian disease of mink parvovirus

“…Viruses and viral DNA. The propagation of the pathogenic strains ADV-Utah 1 (12, 15) and 16,37) in infected mink and the preparation of partially purified virus from organs were done by published procedures (2,12,37). The preparation of single-stranded virion DNA from partially purified strains ADV-Utah I and ADV-Pullman was (10,29) is also shown.…”

“…Comparison of ADV strains has been limited to date but has suggested that the various strains are very similar (1,9,35,37). A major problem in direct molecular comparison relates to the difficulty in growing virulent virus isolates in cell culture.…”