Fernando de Noronha

Polypeptides of mammalian oncornaviruses: II. Characterization of a murine leukemia virus polypeptide (p15) bearing interspecies reactivity☆

Polypeptide p15 from Friend leukemia virus was isolated by multiple gel filtration steps in guanidine hydrochloride. Because of its marked tendency to aggregate, renaturation of the protein was performed in the presence of 0.2% sodium deoxycholate. Serological analyses revealed cross reactivity with other mammalian C-type oncornaviruses.

Isolation and characterization of two group-specific antigens from feline leukemia virus

Abstract Analytical polyacrylamide gel electrophoresis of feline leukemia virus revealed three major protein components, termed EI, EII, and EIII in order of decreasing electrophoretic mobility. Molecular weights of about 15,000, 18,000 and 33,000, respectively, have been found for these proteins. In comparative experiments, mouse leukemia virus (Rauscher) showed a similar electrophoretic pattern, but avian leukemia virus (AMV) a clearly different one. From feline leukemia virus, materials were isolated that behaved electrophoretically like EI and EIII. The EI isolate was characterized serologically as a group-specific (gs) antigenic component, which has thus far been found only in feline leukemia and feline sarcoma viruses. It is termed “gs-spec. antigen.” The EIII protein represents a gs-antigen which occurs in leukemia viruses of other mammalian species as well. It is designated “gs-interspec. antigen.”

Eine Komplementbindungsreaktion zum Nachweis der bei Leukämieviren verschiedener Säuger vorkommenden gemeinsamen antigenen Komponente

By immunization of a rabbit with purified gs-antigen from mouse leukemia virus (MLV) a potent antiserum (R-gs-serum) was obtained, which reacts specifically with gs-antigen of MLV. In cat leukemia virus (KLV) two types of antigens, probably both group specific, could be demonstrated with anti-KLV-sera by Ouchterlony test. One of these was shown with MLV-sera to be identical with a MLV-gs-antigen component. This antigen occurring in both viruses is called gsinterspecies (interspec.) antigen. R-gs-serum allowed to detect gs-interspec. antigen also by the more sensitive CF-test. [Lispa (leukemia virus interspec. antigen) CF-test]. Preliminary experiments with this test indicated that bovine leukosis as well as human cancer cells can produce an agent in tissue culture which is serologically related to MLV.

Enhanced neutralization of feline immunodeficiency virus by complement viral lysis

The ability of complement to inactivate feline immunodeficiency virus (FIV) was examined. Treatment of virus with complement plus sub-neutralizing titers of antiserum resulted in a significant reduction in the virus titer compared with treatment of the virus with complement or antibody alone. One of the mechanisms by which cat complement inactivates FIV was shown to be by viral lysis as determined by a reverse transcriptase release assay. Kinetic studies revealed that viral lysis is initiated soon after the addition of complement to a mixture of virus and antiserum. Treatment of FIV with normal non-complement-inactivated human serum resulted in virus inactivation and release of viral RT in the absence of specific antiserum. It appears that FIV activates complement directly through the classical pathway and that integrity of the membrane attack components is a requirement for FIV lysis by human serum. The vulnerability of two distinct isolates of FIV to complement lysis was compared using complement from different species. Oradell isolate was more sensitive to complement lysis than the Petaluma isolate as assessed by reverse transcriptase release. It appears that factors intrinsic to the virus isolate may influence the amplitude of complement-dependent viral lysis.