Effects of Jin-Ying-Tang on Staphylococcus aureus-induced mastitis in rabbit.

The present study was performed to investigate the effects of Jin-Ying-Tang (JYT), a Chinese herbal formula containing Lonicera japonica, Herba taraxaci, Fructus trichosanthis, Fructus forsythia, Radix et rhizoma rhei, Astragalus membranaceus, Angelica sinensis, on rabbit mastitis induced by Staphylococcus aureus. Suckling rabbits were challenged with 1.5 × 10(7) colony forming unit (CFU) of S. aureus at the base of the third pair teats, and they were treated and pretreated with JYT to detect the formula effects. The results showed that JYT could reduce the occurrence of Staphylococcal mastitis in rabbit model. To further investigate the action mechanism of JYT, we examined the leukocyte counts and inflammatory mediator levels such as TNF-α and IL-6 in blood and infected tissue. From histological study and blood analysis, we found that JYT could suppress leukocyte infiltration in infected mammary gland tissue and significantly inhibit the total leukocyte counts and lymphocytes (LYM), monocytes (MON) and granulocytes (GRA) fractions of leukocyte counts in blood. Enzyme-linked immunosorbent assay (ELISA) results showed JYT significantly decreased the TNF-α and IL-6 concentrations in serum and mammary gland. The analysis of these data suggested that JYT effectively inhibited inflammatory responses to reduce the occurrence of mastitis in rabbit model.

Genome sequence of Shigella flexneri 2a: insights into pathogenicity through comparison with genomes of Escherichia coli K12 and O157.

We have sequenced the genome of Shigella flexneri serotype 2a, the most prevalent species and serotype that causes bacillary dysentery or shigellosis in man. The whole genome is composed of a 4 607 203 bp chromosome and a 221 618 bp virulence plasmid, designated pCP301. While the plasmid shows minor divergence from that sequenced in serotype 5a, striking characteristics of the chromosome have been revealed. The S.flexneri chromosome has, astonishingly, 314 IS elements, more than 7-fold over those possessed by its close relatives, the non-pathogenic K12 strain and enterohemorrhagic O157:H7 strain of Escherichia coli. There are 13 translocations and inversions compared with the E.coli sequences, all involve a segment larger than 5 kb, and most are associated with deletions or acquired DNA sequences, of which several are likely to be bacteriophage-transmitted pathogenicity islands. Furthermore, S.flexneri, resembling another human-restricted enteric pathogen, Salmonella typhi, also has hundreds of pseudogenes compared with the E.coli strains. All of these could be subjected to investigations towards novel preventative and treatment strategies against shigellosis.