Immunogenicity, safety, and reactogenicity of the 10-valent pneumococcal non-typeable Hemophilus influenzae protein D conjugate vaccine (PHiD-CV) when co-administered with the DTPw-HBV/Hib vaccine in Indian infants: a single-blind, randomized, controlled study

In India, pneumococcal diseases are major causes of child mortality, and effective vaccines against Streptococcus pneumoniae are needed. This single-blind, randomized study assessed the immunogenicity, reactogenicity, and safety of the 10-valent pneumococcal non-typeable Hemophilus influenzae (NTHi) protein D conjugate vaccine (PHiD-CV) co-administered with DTPw-HBV/Hib in Indian infants as 3-dose primary vaccination course. A total of 360 infants were randomized (2:1) to receive either PHiD-CV co-administered with DTPw-HBV/Hib (PHiD-CV group) or a Hib vaccine co-administered with DTPw-HBV (control group) at 6, 10, and 14 weeks of age. For each vaccine pneumococcal serotype, the percentage of infants in the PHiD-CV group with antibody concentrations ≥ 0.2 μg/mL one month after the third vaccine dose was at least 98.3%, except for serotypes 6B (77.7%) and 23F (89.5%), and opsonophagocytic activity titers ≥ 8 were measured in at least 95.7% of infants, except for serotypes 1 (90.5%) and 6B (84.5%). In addition, all the infants in the PHiD-CV group were seroprotected against diphtheria, tetanus, Hib, and hepatitis B or seropositive for antibodies against pertussis and NTHi protein D (except one infant). Incidences of solicited local and general symptoms were comparable between groups, except for fever (axillary temperature ≥ 37.5°C), which seemed to occur more frequently in the PHiD-CV group. In conclusion, PHiD-CV was shown to be immunogenic and well-tolerated when co-administered with DTPw-HBV/Hib in Indian infants.     

Binding of vitronectin to opa-expressing Neisseria gonorrhoeae mediates invasion of HeLa cells.

Neisseria gonorrhoeae induces local infections in the human genitourinary tract and can disseminate to other organs to cause severe disease. Blood-derived factors present in the genital mucosa have been suggested to facilitate the spread of N. gonorrhoeae in disseminated gonococcal infections. Using gentamicin invasion assays and confocal microscopy, we observed a strong stimulatory effect of fetal calf serum (FCS) on the gonococcal invasion of HeLa cells. FCS-mediated invasion was dependent on the expression of the epithelial cell invasion-associated Opa protein (plasmid-encoded Opa50 or its chromosomal homolog Opa30), while N. gonorrhoeae expressing noninvasive Opa proteins (Opa(51-60)) or no Opa protein (Opa-) was not invasive even in the presence of FCS. Incubation of N. gonorrhoeae MS11 with biotinylated FCS revealed a 78-kDa protein as the prominent protein binding to Opa50- or Opa30-expressing gonococci. This protein was recognized by antibodies against vitronectin (VN) in Western blots. Purified human or bovine VN efficiently bound to Opa50-expressing gonococci, while binding to noninvasive Opa- or Opa52-expressing gonococci was significantly lower. Binding of VN was inhibited by heparin in a concentration-dependent manner, indicating that the heparin binding sites present in VN or Opa50 may play an essential role in this interaction. Based on gentamicin invasion assays and confocal microscopy studies, VN binding was associated with an increased invasion of Opa50- and Opa30-expressing gonococci into HeLa cells. The ability of VN to mediate entry into epithelial cells may constitute an important event in the pathogenesis of local as well as disseminated gonococcal infections.     

Housekeeping enzymes as virulence factors for pathogens

Housekeeping enzymes are ubiquitously present in almost all living beings to perform essential metabolic functions for the purpose of survival. These enzymes have been characterized in detail for many years. In recent years, there has been a number of reports indicating that some of these enzymes perform a variety of other functions. In case of many pathogens, certain enzymes play a role to enhance virulence. To perform such a function, enzymes must be located on the surface of pathogens. Although they do not have the typical signal sequence or membrane anchoring mechanisms, they do get secreted and are displayed on the surface, probably by their reassociation. Once on the surface, these enzymes interact with host components, such as fibronectin and plasminogen, or interact directly with the host cells, to trigger signal transduction and thereby enable the pathogens to colonize, persist and invade the host tissue. Therefore, certain housekeeping enzymes may act as putative virulence factors and targets for the development of new strategies to control the infection by using agents that can block their secretion and/or reassociation.     

Aberrant expression of nitric oxide synthase in human polyps, neoplastic colonic mucosa and surrounding peritumoral normal mucosa

The expression of nitric oxide synthase (NOS) was studied byNAD(P)H diaphorase histochemical localization method in (i)individual cells of the normal colonic mucosa (n = 13) whichserved as control, (ii) colonic polyps (n = 14), (iii) coloniccarcinoma (n = 20) and (iv) peritumoral mucosa (2 and 5 or 10cm away from the tumor). Four of the tumor specimens had normalepithelium adjacent to the cancer, which thus served as an internalcontrol. The expression of NOS activity in colon cancer wassignificantly reduced as compared to the control group of individuals(P < 0.004); undetectable in 25%, diminished in 45%, normalin 30%. On comparing the expression in normal mucosa and polypsthere was a significant reduction of the expression in polyps(P < 0.027); undetectable in 14%, reduced in 35%, normalin 51%. When compared to the peritumoral mucosa at 2 and 10cm the tumor showed a significant reduction in expression ofNOS activity (P < 0.001 and P < 0.0001 respectively).There was no significant difference seen in the expression at2 and 10 cm (P = 0.329). The peritumoral mucosa at a distanceof 2 cm away from the tumor when compared to the control mucosashowed no significant difference (P = 1.000), although thereis a tendency to a high normal expression of NOS activity inthe mucosa at a distance of 2 cm. Similarly, there was no significantdifference between the control mucosa and the peritumoral mucosaobtained at a distance of 10 cm (P = 0.383). The expressionof NOS activity in all tissues examined was abolished by preincubationof tissue with the selective NOS inhibitor L–NMMA butnot with D–NMMA. Our data showed extensive and significantreduction as identified by the NAD(P)H diaphorase method inthe expression of NOS activity, thereby reflecting the activityof nitric oxide in colon cancer and colonic polyps. The generalizedsuppression of this activity, which precedes the onset of overtneoplasia, may be an important event in colon carcinogenesis.This aberrant expression could also be compatible with the selectiveadvantage to either tumor promotion and metastatic progressionor to tumoricidal activity.     

Release of Fc-receptors after streptococcal lysis induced by a lytic enzyme fromStreptomyces globisporus

Streptomyces globisporus produced an enzyme which had lytic effects on streptococci and was able to solubilize their Fc-receptors. A new method for rapid purification of this enzyme was described. It consisted of adsorption to Amberlite CG 50 and subsequent chromatography on CM-cellulose Whatman CM 52. The purified enzyme was free of proteases and had lysed streptococci of serological groups A, B, C, G and L. It released Fcreceptors from the streptococcal surface in a biologically active form.     

Fibronectin-binding protein gene recombination and horizontal transfer between group A and G streptococci

We report evidence of interspecies gene transfer between the important virulence factor genes sfbI and gfbA. Because the identified group G streptococcus gfbA types possess DNA cassettes that can be identified in a number of group A streptococcus strains, it appears that homologous recombination is occurring between these species.     

Prospects for a group A streptococcal vaccine

Group A streptococcal (GAS) infections are associated with a number of human diseases, including pharyngitis, impetigo, necrotizing fasciitis, streptococcal toxic shock syndrome and rheumatic heart disease. An increase in the incidence of severe GAS infections in Western countries, and the awareness of the burden of GAS-associated diseases in developing nations, which remains high in spite of the availability of antibiotics, has provided the impetus for development of a safe and efficacious GAS vaccine. This has focused on the M protein, a major GAS virulence factor, however, with the publication of several GAS genomes, a number of non-M vaccine candidates are now under investigation.