Summary. DNA hybridisation of 309 consecutive Staphylococcus aureus clinical isolates with oligonucleotide probes specific for genes encoding Panton-Valentine leucocidin (luk-PV) and y-haemolysin (hlg) revealed that 99% of randomly selected strains carried the hlg locus whereas only 2 YO harboured the luk-PV as well as the hlg loci. Only 1 YO of the strains did not possess either gene. In a clinical prospective study of independent S . aureus strains, 58 Panton-Valentine leucocidin (PVL)-producing isolates were shown to be responsible for primary skin infections, mainly furuncles (86 YO). Phage susceptibility patterns and pulsed field gel electrophoresis (PFGE) profiles of DNA were shown to be polymorphic epidemiological markers of PVL-producing strains. In eight patients with recurrent furuncles, the PVL-producing strains isolated either from furuncles or from the anterior nares were considered to be identical in each based upon phage sensitivity profiles or PFGE patterns.

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We have studied 52 new HHV8 strains by sequencing the complete hypervariable K1 gene and genotyping the K14.1/K15 loci located at both sides, respectively, of the viral genome. The samples originated from 49 patients with Kaposi's sarcoma (KS; 32 patients), multicentric Castleman's disease (MCD; 12 patients), or primary effusion lymphoma (PEL; 5 patients). Among these patients, 32 were of African origin (West and Central African countries and Creoles from French Guiana) and the 17 others were mostly French homosexuals. Comprehensive phylogenetic studies allowed the identification of distinct groups within the three already known main subtypes. Interestingly, two new sequences that did not cluster within a known subtype or group could be considered as prototypes of early/ancient variants of the C subtype and A/C set, respectively. Among the 32 African strains, the majority were either of the B subtype (13 cases) or of the A5 group (11 cases), indicating that this latter genotype is frequent and widespread in Africa. In contrast, a subtype C strain infected most of the 17 other patients. PCR-based genotyping of the K14.1/K15 loci revealed an overall predominance of P subtype, except in the A5 and B K1 groups, in which the P and M alleles were equally represented. The implications of these data on the evolution and spread of HHV8 among human African populations are discussed.

Panton-Valentine leukocidin (PVL) is a Staphylococcus aureus (SA) exotoxin, which kills human granulocytes and monocytes in vitro. Among 43 SA strains from cutaneous infections, 12 were PVL producers, whereas among 49 blood culture strains, only 1 produced PVL. Most PVL-producing strains (11/22) came from 22 primitive cutaneous infections, especially furuncles and abscesses, while only 1 PVL-producing strain came from 21 secondary infections of dermatoses such as bullous or pruritic diseases. Intradermal injections of PVL in rabbits induced edema, erythema and necrosis; histopathological changes at the injection sites consisted mainly in leukocytoclasis and vascular necrosis. All changes were dose dependent, and previous immunization of rabbits partially neutralized PVL-induced effects. Production of PVL in vivo after injections of bacteria seems to be low, and the histopathological lesions induced in the rabbit skin do not appear to be specifically related to PVL activity. However, PVL is a good candidate as a new virulence factor in cutaneous SA infections.