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“The human monoclonal antibody b12 recognizes a conserved epitope on gp120 that overlaps the CD4 binding site. b12 has neutralizing activity against diverse human immunodeficiency virus type 1 (HIV-1) strains. However, we recently reported that b12 sensitivity of HIV-1 envelopes amplified from patient tissues without culture varied considerably. For two subjects, there was clear modulation of b12 sensitivity, with lymph node-derived envelopes being essentially resistant
while those from brain tissue were sensitive. Here, we have mapped envelope determinants of b12 resistance by constructing chimeric envelopes from resistant and sensitive envelopes derived from lymph node and brain tissue, respectively. Residues on the N-terminal flank of the CD4 binding loop conferred partial resistance. However, a potential glycosylation site at residue N386 completely modulated selleck chemicals b12 resistance but required the presence of an arginine
at residue 373. Moreover, the introduction of R373 into b12-sensitive NL4.3 and AD8 envelopes, which carry N386, also conferred b12 resistance. Molecular modeling suggests that R373 and the glycan at N386 may combine to sterically exclude the benzene ring of this website b12 W100 from entering a proximal pocket. In summary, we identify residues on either side of the CD4 binding loop that contribute to b12 resistance in immune tissue in vivo. Our data have relevance for the design of vaccines that aim to elicit neutralizing antibodies.”
“Rotavirus infection of cells in culture induces major changes in Ca(2+) homeostasis. These changes include increases in plasma membrane Ca(2+) permeability, cytosolic Ca(2+) concentration, and total cell Ca(2+) content and a reduction in the amount of Ca(2+) released from intracellular pools sensitive to agonists. Various lines of evidence suggest
that the nonstructural glycoprotein NSP4 and possibly the major outer capsid glycoprotein VP7 are responsible for these effects. In order to evaluate the functional roles of MycoClean Mycoplasma Removal Kit NSP4 and other rotavirus proteins in the changes in Ca(2+) homeostasis observed in infected cells, the expressions of NSP4, VP7, and VP4 were silenced using the short interfering RNA (ARNA) technique. The transfection of specific siRNAs resulted in a strong and specific reduction of the expression of NSP4, VP7, and VP4 and decreased the yield of new viral progeny by more than 90%. Using fura-2 loaded cells, we observed that knocking down the expression of NSP4 totally prevented the increase in Ca(2+) permeability of the plasma membrane and cytosolic Ca(2+) concentration measured in infected cells. A reduction in the levels of VP7 expression partially reduced the effect of infection on plasma membrane Ca(2+) permeability and Ca(2+) pools released by agonist (ATP).