The rat corpulent (cp) mutation maps to the same interval on (Pgm1-Glut1) rat chromosome 5 as the fatty (fa) mutation.

The autosomal recessive obesity mutations fatty (fa) and corpulent (cp) arose in separate rat strains, 13M and Koletsky, respectively. By complementation analysis, the two mutations appear to be in the same gene. The somewhat different phenotypes of fa/fa and cp/cp animals probably reflect the fact that the mutations are segregating on different rat strains. The fa mutation has been mapped to the interval between Pgm1 and Glut1 on rat Chr 5, but cp has not been mapped genetically. We mapped cp in 30 obese progeny of a LA/N-BN cp/+ intercross using microsatellite markers for these flanking genes. Cp maps to the same genetic interval as rat fa and mouse db. Cp is flanked by Glut1 and Pgm1: Pgm1-------- cp -------- Glut1 map distance (cM) 1.67 6.67 Thus, cp and fa map to the same approximately 8 cm interval of the rat genome. In conjunction with the complementation studies alluded to above, these findings indicate that cp and fa are mutations in the same gene (Lepr).

Dependence on antibody for induction of chemiluminescence in polymorphonuclear leukocytes by herpes simplex virus.

The induction of luminol-dependent chemiluminescence in rabbit polymorphonuclear leukocytes (PMN) by a stromal keratitis causing strain (RE) of herpes simplex virus type 1 (HSV-1) was examined. Virus alone and virus infected rabbit corneal cells were unable to stimulate chemiluminescence. However, when the virus or virus infected cells were incubated in the presence of HSV-1 specific immune serum or purified IgG, a gradual chemiluminescent response was observed. Virus and virus infected cells incubated with normal rabbit serum or IgG produced little or no activity. No impairment of chemiluminescent response was observed in experiments in which rabbit PMN were exposed to HSV prior to the addition of opsonized zymosan or HSV-antibody complexes. Results suggest PMN exert antiviral activity in the presence of specific antibody and may be important factors in the inflammatory process resulting from ocular HSV infection.

Blocking induction of human cytotoxic T lymphocytes with anti-Ia xenoantiserum.

A xenoantiserum to human Ia antigens has been described that is capable of blocking not only stimulation in the mixed lymphocyte reaction (MLR) but also the induction of cytotoxic T lymphocytes (CTLs). Data from immunofluorescence as well as complement-dependent cytolytic assays indicate that the anti-Ia xenoantiserum is directed against B cell surface antigens. Inhibition of complement-dependent cytolysis with column fractions of B cell antigens and autoradiography of immune precipitates electrophoresed on sodium dodecyl sulfate (SDS)-polyacrylamide gels have established that the antigen detected by the xenoantiserum has characteristics of the human two-polypeptide Ia molecular complex. Allogeneic stimulator cells pretreated with anti-Ia at very low doses were unable to stimulate in the MLR and failed to induce CTLs. Neither anti-beta 2-microglobulin nor a non-HLA-associated antilymphocyte serum in similar dose ranges inhibited MLR or cell-mediated lympholysis (CML) assays. Absorption of anti-Ia xenoantiserum with B lymphoblasts, but not T lymphoblasts, removed inhibitory activity for both MLR and CML. Untreated third-party stimulator cells cocultivated with anti-Ia-pretreated stimulator cells provided stimulation in the MLR that apparently allowed partial recovery of CML against targets from the same donor as the anti-Ia-treated stimulator cells. Elimination of the helper effect, normally provided by MLR stimulation, may be one mechanism by which anti-Ia xenoantiserum prevents induction of CTLs.

Analysis of immunoprecipitated surface glycoproteins in measles virions and in membranes of infected cells.

Measles viral envelope proteins were immune precipitated from membranes of infected cells and from purified virus and analyzed by polyacrylamide gel electrophoresis. Under reducing conditions, specific precipitates contained two major polypeptide bands, designated virus glycopeptides 1 and 2 (VGP-1 and VGP-2). Both polypeptides appeared to be glycosylated, as indicated by their incorporation of [(14)C]glucosamine in infected cells. VGP-2 appeared as a single band in specific precipitates of infected cells and as a double band in precipitates of purified virus. Trypsin treatment of infected cells showed that reduced VGP-2 may be composed of two unrelated polypeptides. One may be F(1), which is unglycosylated, and the other may correspond to the proteolytic cleavage product of VGP-1, which is glycosylated. The relation of VGP-1 and VGP-2 to smaller surface antigens (X and Y) obtained by tryptic treatment of infected cells remains to be elucidated. In cells taken at various times postinfection and analyzed for viral membrane proteins, VGP-1 was detected at all times, indicating that the input virus VGP-1 was inserted into the cell and could not be differentiated from newly synthesized VGP-1. VGP-2 was not detectable before 24 h postinfection. In precipitates of cells 4 h postinfection and of infected cells incubated at pH 5.8, an additional polypeptide band migrated immediately ahead of VGP-1. We conclude that VGP-2 (molecular weight, 42,000) possibly consists of two components, one of which is the tryptic cleavage product of VGP-1 and the other of which is the unglycosylated polypeptide, F(1).

Complement-mediated cytolysis of HSV-1 and HSV-2 infected cells: plasma membrane antigens reactive with type-specific and cross-reactive antibody.

Surface antigens of BHK-21 cells infected with HSV-1 or HSV-2 were radioiodinated (125I) with lactoperoxidase, immune precipitated and analysed by polyacrylamide gel electrophoresis (PAGE). Experiments using antiserum to HSV-1 or HSV-2, absorbed with appropriate hemotypic or heterotypic antigens, revealed that both type-specific (homotypic) and cross-reactive antibody combined with surface glycoproteins to form a single large radioactive peak. This peak, which constituted the major glycoprotein region (region a) observed in electropherograms, represented a range in mol. wt. from 115000 to 130000. Sensitization of cells to complement lysis, neutralization of infectious virus and immune precipitation of surface glycoproteins (region a) were found to be generally correlated properties of all the antibody preparations analysed, including antibody prepared specifically against region a antigens. These findings suggest a major immunological role for the surface glycoproteins migrating in PAGE region a.