The relative contribution to transmission by find more cell-associated or cell-free virus is still not defined for the different routes

of transmission. Although the main target cells for HIV-1 replication are the CD4+ T lymphocytes, which are rapidly depleted both in the periphery and in the mucosal tissues, dendritic cells, Langerhans’ cells, and macrophages are players in each of these processes. The predominant cells involved may differ according to the tract of the gut and the route of transmission. The microenvironment of the intestinal mucosa, including mucus, antibodies, or chemo-cytokines, can as well influence infection and replication of the virus: their role is still under investigation. The understanding of these processes may help in developing efficient prevention strategies. “
“The O-polysaccharide chain of the lipopolysaccharide (O-antigen) on the bacterial cell surface is one of the most structurally variable cell components and serves as a basis for serotyping of Gram-negative bacteria, including human opportunistic

pathogens of the genus Providencia. PD-332991 In this work, the O-antigen of Providencia alcalifaciens O40 was obtained by mild acid degradation of the isolated lipopolysaccharide and studied by chemical methods and high-resolution NMR spectroscopy. The following structure of the O-polysaccharide was established: 4)-β-d-Quip3NFo-(13)-α-d-Galp-(13)-β-d-GlcpA-(13)-β-d-GalpNAc-(1,

where GlcA stands for glucuronic acid and Qui3NFo for 3,6-dideoxy-3-formamidoglucose. The GABA Receptor O40-antigen was found to be structurally and serologically related to the O-antigens of P. alcalifaciens O5 and Providencia stuartii O18. The O40-antigen gene cluster between cpxA and yibK was sequenced, and the gene functions were predicted in silico. In agreement with the O-polysaccharide structure established, the genes for the synthesis of dTDP-d-Qui3NFo, UDP-d-Gal, UDP-d-GlcA, and UDP-d-GalNAc as well as those encoding three glycosyltransferases, flippase (Wzx), and O-antigen polymerase (Wzy) were recognized. In addition, homologues of wza, wzb, and wzc genes, which are required for the surface expression of capsular polysaccharides, were found within the gene cluster, suggesting that the O-polysaccharide studied is a part of the capsule-related form of the lipopolysaccharide called KLPS. Gram-negative bacteria of the genus Providencia are opportunistic pathogens that are isolated from a wide variety of environment and organisms, ranging from fruit flies and sea turtles to humans (Galac & Lazzaro, 2011). Currently, the genus consists of eight species (O’Hara et al., 2000; Somvanshi et al., 2006; Juneja & Lazzaro, 2009), among which P. stuartii, P. rettgeri, P. rustigianii, and P. alcalifaciens are the most common Providencia species that cause human infection. P.