An ahemolytic pneumolysin of Streptococcus pneumoniae manipulates human innate and CD4⁺ T-cell responses and reduces resistance to colonization in mice in a serotype-independent manner

BACKGROUND

Some Streptococcus pneumoniae serotypes express an ahemolytic pneumolysin (PLYa). Serotypes that commonly express PLYa, including serotype 8 (ST8) and ST1, are often associated with a low prevalence during colonization but a higher propensity to cause invasive disease. We sought to study the host response to ST8 PLYa in a homologous and heterologous capsular background.

METHODS

We genetically exchanged the PLYa of ST8 strain 6308 with the hemolytic PLY (PLYh) of ST3 A66.1 and vice versa and determined the impact of the exchange on nasopharyngeal colonization in mice. Then, to compare the response of human cells to PLYa-expressing and PLYh-expressing strains, we infected human peripheral blood mononuclear cells (PBMCs) with PLY-switched strains and assessed dendritic cell and CD4(+) T-cell responses by intracellular cytokine staining.

RESULT

Mice colonized with PLYa-expressing strains had significantly higher colonization densities than those colonized with PLYh-expressing strains, irrespective of capsular background. Compared with infection of PBMCs with PLYh-expressing strains, infection with PLYa-expressing strains induced diminished innate (dendritic cell cytokines, costimulatory receptor, and apoptotic) and adaptive (CD4(+) T-cell proliferative and memory interleukin 17A) responses.

CONCLUSION

Our findings demonstrate that PLYa has the potential to manipulate host immunity irrespective of capsule type. PLY exchange between STs expressing PLYa and PLYh could lead to unexpected colonization or invasion phenotypes.

Cloning, expression, and immunological characterization of the P30 protein of Mycoplasma pneumoniae

Mycoplasma pneumoniae, a self-replicating cell wall-deficient prokaryote, has a differentiated terminal organelle that is essential for cytadherence and gliding motility. P30, an important protein associated with the terminal organelle, is required for the cytadherence and virulence of M. pneumoniae. P30 is a transmembrane protein with an intracytoplasmic N terminus and an exposed C terminus. In the present study, we amplified and sequenced the full-length p30 gene of Mycoplasma pneumoniae directly from 18 Indian asthmatic patients. Sequence diversity was observed in the p30 genes from 16 clinical samples when the sequences were compared with the sequence of strain M-129. We also successfully expressed a fragment of the p30 gene (P30B) that includes the complete C-terminal proline-rich amino acid sequences in different Escherichia coli expression systems. The maltose binding protein (MBP)-P30B fusion protein was recognized by M. pneumoniae-infected patient sera in immunoblots, and the protein was immunogenic in mice. We further analyzed the reactivity of the MBP-P30B fusion protein with patient sera in an enzyme-linked immunosorbent assay (ELISA) and compared it with the reactivity obtained with a commercial kit (the Serion ELISA Classic kit). The sensitivity and the specificity of the in-house ELISA were 78.57% and 89.47%, respectively. This study suggests that the P30 protein can be used as an antigen along with other adhesin proteins for the immunodiagnosis of M. pneumoniae infection.

Adhesion proteins of Mycoplasma pneumoniae

Mycoplasmas are unique cell wall deficient, cholesterol requiring, highly pleomorphic bacteria that possess very small genome. M. pneumoniae is an important human pathogen that possesses specialized tip organelle to mediate cytadherence. It is a complex multifactorial process requiring a group of mycoplasma proteins such as P1, P30, P116 and HMW1-3. Expression of major mycoplasma adhesin proteins in heterologous expression systems provides an opportunity to study the role(s) of these proteins in pathogenicity and helps to develop diagnostic reagents. In this review we highlight the role(s) of various cytadhesin proteins of M. pneumoniae.

Synthetic, structural, and biochemical studies of organotin(IV) with Schiff bases having nitrogen and sulphur donor ligands

Three bidentate Schiff bases having nitrogen and sulphur donor sequences were prepared by condensing S-benzyldithiocarbazate (NH(2)NHCS(2)CH(2)C(6)H(5)) with heterocyclic aldehydes. The reaction of diphenyltin dichloride with Schiff bases leads to the formation of a new series of organotin(IV) complexes. An attempt has been made to prove their structures on the basis of elemental analyses, conductance measurements, molecular weights determinations, UV, infrared, and multinuclear magnetic resonance ((1)H, (13)C, and (119)Sn) spectral studies. Organotin(IV) complexes were five- and six-coordinate. Schiff bases and their corresponding organotin complexes have also been screened for their antibacterial and antifungal activities and found to be quite active in this respect.

Effect of some ultraviolet light absorbers on photo-stabilization of azadirachtin-A

The effect of photo-stabilization of Azadirachtin-A (Aza-A) was examined when exposed to sunlight and ultraviolet light in the presence of four structurally different ultraviolet stabilizers namely 4-aminobenzoic acid, 2,4-dihydroxybenzophenone, 4,4'-dihydroxybenzophenone and phenyl salicylate. The percentages of Aza-A recovered at different time intervals from slides exposed to different light conditions with and without UV stabilizers as well as kinetic studies indicated that the addition of phenyl salicylate in methanolic solution of Aza-A (in 1:1 mole ratio) provides the best photo-stabilization of Aza-A molecule among the four UV stabilizers studied.

Radon estimation in some Indian tobacco, tea and tooth powder using CR-39 nuclear track detector

Radon contents in some samples of tobacco, tea and tooth powder have been estimated using CR-39 solid state nuclear track detectors. The Radon content in tobacco has been found to vary from 14.06 +/- 1.4 to 89.91 +/- 3.3 mBq/l. The Radon content in tea and tooth powder has been found to vary from 27.38 +/- 1.8 to 41.81 +/- 2.2 mBq/l and 26.27 +/- 1.4 to 413 +/- 6.0 mBq/l respectively. The present investigations are useful from the health hazards point of view.