The DNA encoding the exfoliative toxin A gene (eta) of Staphylococcus aureus was cloned into bacteriophage Xgtll and subsequently into plasmid pLI50 on a 1,391-base-pair DNA fragment of the chromosome. Exfoliative toxin A is expressed in the Escherichia coli genetic background, is similar in length to the toxin purified from culture medium, and is biologically active in an animal assay. The nucleotide sequence of the DNA fragment containing the gene was determined. The protein deduced from the nucleotide sequence is a polypeptide of 280 amino acids. The mature protein is 242 amino acids. The DNA sequence of the exfoliative toxin B gene was also determined. Corrections indicate that the amino acid sequence of exfoliative toxin B is in accord with chemical sequence data.The exfoliative toxins A and B (ETA and ETB) of Staphylococcus aureus are the causative agents of staphylococcal scalded-skin syndrome (11). They possess the same biological activity (12), but they are immunologically distinct proteins (11, 12). The two forms also differ in amino acid composition, amino acid sequence, and heat resistance (13). In addition, eta is expressed from the chromosome, whereas etb is of plasmid origin (14,21,29).To study the mode of action and the molecular properties of these two proteins, we set out to clone and sequence both genes. Recently, we reported the cloning and sequencing of the etb gene (9, 10). In this communication, we report the cloning and DNA sequence of eta. O'Toole and Foster (17) also reported the cloning of eta and in the accompanying paper (18) report their sequence of the gene. Our data and their report contain identical DNA sequence determinations as well as general conclusions regarding the expression of the eta gene. eta is expressed in the Escherichia coli background and is biologically active in the neonatal mouse assay. Furthermore, the sequence of the protein deduced from the DNA sequence is identical to the published sequence of the N-terminal region of the ETA molecule (12). MATERIALS AND METHODSBacterial strains and plasmids. S. aureus UT0002, a phage group II staphylococcal scalded-skin syndrome clinical isolate (20), was used as the source of library DNA. E. coli Y1090 was used in the Protoclone system (Promega Biotec Co., Madison, Wis.) as a recipient for bacteriophage Xgtll packaging carried out according to the manufacturer's instructions. E. coli LE392 was used for transformation and propagation of plasmids and cloned DNA (16).* Corresponding author.

An exfoliatin B-producing strain of Staphylococcus aureus was isolated from two adults with typical staphylococcal scalded skin syndrome (SSSS). One patient developed desquamation after a local staphylococcal infection of the hand, and the other developed exfoliation after nosocomially acquired staphylococcal endocarditis. Neither patient was immunocompromised, had evidence of renal insufficiency, or manifested other potential risk factors for SSSS. Purified toxin, isolated from the causative organisms, produced a Nikolsky sign in neonatal mice. The toxins were shown to be exfoliatin B by biochemical and immunologic methods and heretofore had been described only in children with SSSS. Analysis of plasmid DNAs from both strains revealed a 23-megadalton plasmid with identical restriction endonuclease digestion fragments. One isolate belonged to phage group Il (3B/3C/6/7/47/54/55), whereas the other isolate belonged to phage groups I and III (7/29/52/52A153/54/80). The observation that a non-phage group Il exfoliatin-producing strain of S. aureus may produce SSSS in adults indicates the need to better define the diagnostic criteria for SSSS. Immunocompetent adults may remain susceptible to some strains of exfoliatin B-producing S. aureus.

Isolation of epidermal lamellar bodies has presented a challenge because pressures required to homogenize keratinocytes can destroy these organelles and because the lamellar body readily releases its contents during prolonged isolation procedures. In an attempt to isolate lamellar bodies, sheets of intact stratum corneum and stratum granulosum were obtained from neonatal mice with highly purified staphylococcal epidermolytic toxin, disrupted, and passed through a series of filters. The final filtrate was rich in intact lamellar bodies and contained variable amounts of ribosomes and other vesicular structures. Availability of a highly purified lamellar body preparation from postnatal epidermis should help to clarify the role of this organelle in epidermal function. The technique of selective, sequential filtration represents a new approach to cell fractionation that may have wide applications in cell biology and biochemistry.

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