Production and partial characterization of monoclonal antibodies against erythrogenic toxins type A and C from Streptococcus pyogenes

Early phase karyotype analysis of chromosome segregation after formation of mouse-mouse hybridomas with chromosome painting probes

FISH analysis with chromosome painting probes allows, better than karyotyping after Giemsa banding, the study of chromosome segregation after hybridoma formation. FISH is particularly useful for intraspecies hybrids and allows visualization of small chromosome fragments. Cell hybrids were constructed between P3 x 63Ag8.653 mouse myeloma cells and lymphocytes from BALB/c mice by PEG fusion and by selection in hypoxanthine azaserine medium. Three hybridomas (A4, D8, F10) were selected and, after cloning, the cells were cultivated in vitro over a period of 28 days. During this time in culture, air-dried metaphase spreads were prepared by standard methods. For FISH chromosome painting, digoxigenin- and biotin-labeled mouse chromosome painting probes and rhodamine-antidigoxigenin antibodies and fluorescein-avidin were used for dual color detection. Total chromosome numbers and the numbers of mouse chromosomes 1, X, 6 and 12 were estimated as function of days in culture. Mean chromosome numbers of 78 (D8), 82 (F10) and 150 (A4) were observed. The major rearrangements of chromosome numbers occured in the first 28 days in culture and did not change significantly between day 28 and day 56. Mouse chromosome #12, which had the largest chromosome fragments in the parent myeloma, remained stable while the number of X chromosomes, which were significantly fragmented already in the parent myeloma, decreased by approximately 50%.

Relative avidities of human immunoglobulin G antibodies for streptococcal pyrogenic exotoxins A and B

In this pilot study, we investigated the relative avidities for streptococcal pyrogenic exotoxin A (SPE-A) and SPE-B of antibodies in sera from patients with fatal streptococcal toxic shock-like syndrome and from healthy individuals and in intravenous immunoglobulin (IVIG) preparations. We observed a great variation in the relative avidities of patient, control, and IVIG immunoglobulin G (IgG) (values estimated to be between 10(-7) and 10(-11) M), with mean values for patient IgG about 10-fold lower than those of control IgG.

Influence of the phosphorylation state on the biological activity of a low-molecular mitogen from group A streptococci

A low molecular weight mitogen (LMP) from Streptococcus pyogenes strain NY 5 was successively purified by adsorption on phenylsepharose, chromatography on Resource S and Superdex G 30 and finally by affinity chromatography on antiphosphothreonine agarose. The N-terminal protein sequence of the mitogen was determined. The occurrence of phosphoamino acids was investigated by immunoassay using monoclonal antibodies. The LMP is a threonine-phosphorylated protein different of HPR protein of PTS-system, its mitogenic activity was lost after treatment with streptococcal protein phosphatase or alkaline phosphatase. The inactivated LMP was activated by phosphorylation with phosphokinase and ATP. The active LMP was also inactivated in streptococcal cultures secreting acid protein phosphatase during the phase of phosphate limitation.

Kinetics and regulation of erythrogenic toxins type A and C during growth of Streptococcus pyogenes

The production of erythrogenic toxins type A (ETA) and C (ETC) is described as a function of growth kinetics. Group A streptococcal strains C 203 S and NY 5 were cultivated in yeast-peptone extract, Todd-Hewitt medium and a synthetic medium. Two main growth phases occurred during growth: a first logarithmic phase and a second linear phase. These phases were separated by a short stationary interphase caused by limitation of the amino acids L-serine and L-leucine. Maximum production of ETC was observed during the logarithmic phase, it was correlated to a high level of viable cells. ETA was produced mainly during the short stationary interphase. The production of ETC is regulated by L-isoleucine. A stagnation or reduction of the concentration of viable cells was observed during the interphase. The phosphate limitation caused during streptococcal growth induced expression of the extracellular protein phosphatase and surprisingly, of a serine proteinase activity. The association between these results and the pathogenicity of streptococci is discussed.

Mitogenicity of M5 protein extracted from Streptococcus pyogenes cells is due to streptococcal pyrogenic exotoxin C and mitogenic factor MF

M proteins of Streptococcus pyogenes are virulence factors which impede phagocytosis, bind to many plasma proteins, and induce formation of cross-reactive autoimmune antibodies. Recently, it has been reported that some M proteins, extracted with pepsin from streptococci (pep M), are superantigens. One of these, pep M5, was investigated in detail and was shown to stimulate human T cells bearing V beta 2, V beta 4, and V beta 8. In the present study, we extracted and purified M5 protein by different biochemical methods from two M type 5 group A streptococcal strains. The crude extracts were fractionated by affinity chromatography and ion-exchange chromatography. All fractions were tested in parallel for M protein by immunoblotting and for T-cell-stimulating activity. Although several crude preparations of M5 protein were associated with mitogenicity for V beta 2 and V beta 8 T cells, the M5 proteins, irrespective of the extraction method, could be purified to the extent that they were no longer mitogenic. The mitogenic activity was not destroyed during the purification procedures but was found in fractions separated from M protein. In these fractions, streptococcal pyrogenic exotoxin C and mitogenic factor MF could be detected by protein blotting and enzyme-linked immunosorbent assay. Moreover, anti-M protein sera did not inhibit the mitogenic activity of crude extracts, but antisera which contained anti-streptococcal pyrogenic exotoxin C antibodies showed inhibition. The inability of M5 protein to stimulate T cells was confirmed with recombinant pep M5 produced in Escherichia coli. Our data strongly suggest that the mitogenic activity in M protein preparations is caused by traces of streptococcal superantigens different from M protein.