Kegg Pathway: Cholera - Infection

J Wildl Dis. 2009 Oct; 45(4): 1194-7
Wang C, Wu Y, Xing X, Hu G, Dai J, He H

Eleven species of wild waterfowl (Anseriformes and Charadriiformes) were found dead in the Hongjian Nur Lake in the Ordos wetland, Inner Mongolia of northern China, in 2007. Pasteurella multocida was isolated from tissue samples of dead and sick birds and identified as P. multocida subsp. multocida, serotype A1, using serologic and molecular techniques. Eight bird species in this outbreak had never been previously reported with P. m. multocida Infection. This was also the first report of fowl Cholera in wild waterfowl in China.

Proc Natl Acad Sci U S A. 2009 Nov 2;
Lee H, McKeon RJ, Bellamkonda RV

Chondroitin sulfate proteoglycans (CSPGs) are a major class of axon growth inhibitors that are up-regulated after spinal cord injury (SCI) and contribute to regenerative failure. Chondroitinase ABC (chABC) digests glycosaminoglycan chains on CSPGs and can thereby overcome CSPG-mediated inhibition. But chABC loses its enzymatic activity rapidly at 37 degrees C, necessitating the use of repeated injections or local infusions for a period of days to weeks. These infusion systems are invasive, Infection-prone, and clinically problematic. To overcome this limitation, we have thermostabilized chABC and developed a system for its sustained local delivery in vivo, obviating the need for chronically implanted catheters and pumps. Thermostabilized chABC remained active at 37 degrees C in vitro for up to 4 weeks. CSPG levels remained low in vivo up to 6 weeks post-SCI when thermostabilized chABC was delivered by a hydrogel-microtube scaffold system. Axonal growth and functional recovery following the sustained local release of thermostabilized chABC versus a single treatment of unstabilized chABC demonstrated significant differences in CSPG digestion. Animals treated with thermostabilized chABC in combination with sustained neurotrophin-3 delivery showed significant improvement in locomotor function and enhanced growth of Cholera toxin B subunit-positive sensory axons and sprouting of serotonergic fibers. Therefore, improving chABC thermostability facilitates minimally invasive, sustained, local delivery of chABC that is potentially effective in overcoming CSPG-mediated regenerative failure. Combination therapy with thermostabilized chABC with neurotrophic factors enhances axonal regrowth, sprouting, and functional recovery after SCI.

Scand J Infect Dis. 2009 Nov 2;
Khan AI, Chowdhury F, Harris JB, Larocque RC, Faruque AS, Ryan ET, Calderwood SB, Qadri F

Abstract Vibrio Cholerae O1, Ogawa and Inaba serotypes, both cause severe Cholera. We compared clinical and immunological features in patients in Bangladesh infected with these 2 serotypes. Blood was collected from hospitalized Ogawa (N=146) or Inaba (N=191) patients at the acute stage (day 2) and 5 and 19 days later. Ogawa patients were younger than Inaba, presented with shorter duration of diarrhoea, and had more frequent abdominal pain, vomiting and need for intravenous fluids (p<0.05). Inaba patients more frequently had dark-field positive stools (p<0.01). Inaba strains were more susceptible to tetracycline and erythromycin than Ogawa strains (p<0.001). Ogawa Infection produced higher plasma vibriocidal as well as IgG responses to Cholera toxin B subunit, toxin-coregulated pilus subunit and lipopolysaccharide (LPS); higher IgA responses to LPS in 'antibody in lymphocyte supernatant' (ALS) specimens were also seen. These results suggest that a Cholera vaccine based on the Ogawa serotype needs to be further investigated.

Infect Immun. 2009 Oct 26;
Tsou AM, Zhu J

Recent work has shown that in addition to Cholera Toxin (CT) and the Toxin Coregulated Pilus (TCP), other cytotoxic proteins in Vibrio Cholerae also cause disease symptoms, and this is particularly evident in strains lacking CT. One such protein is the hemolysin encoded by hlyA. Here, we show that, like CT and TCP, HlyA is repressed by the quorum sensing-regulated transcription factor, HapR. This repression occurs on two levels: one at the transcriptional level that is independent of the metalloprotease, HapA, and one at the post-translational level that is mediated by HapA. The transcriptional regulation is significantly more apparent on solid media than in liquid cultures. This is the first time that hemolysis has been shown to be directly regulated by quorum sensing in V. Cholerae, and it is interesting that, like other virulence factors, HlyA is also repressed by HapR, which is expressed late in Infection.

Infect Immun. 2009 Oct 26;
Kendall EA, Tarique AA, Hossain A, Alam MM, Arifuzzaman M, Akhtar N, Chowdhury F, Khan AI, Larocque RC, Harris JB, Ryan ET, Qadri F, Calderwood SB

Vibrio Cholerae O1 can cause severe watery diarrhea that can be life-threatening without treatment. Infection results in long-lasting protection against subsequent disease. Development of memory B cells of the IgG and IgA isotypes to V. Cholerae O1 antigens including serotype-specific lipopolysaccharide (LPS) and the B subunit of Cholera toxin (CTB) has been demonstrated following Cholera. Memory B cells of the IgM isotype may play a role in long-term protection, particularly against T cell-independent antigens, but IgM memory has not been studied in V. Cholerae O1 Infection. Therefore, we assayed acute and convalescent blood samples from 32 Cholera patients for the presence of memory B cells that produce Cholera-antigen-specific IgM antibody upon polyclonal stimulation in in vitro culture. We also examined the development of serological and antibody-secreting-cell responses following Infection. Subjects developed significant IgM memory responses by day 30 after Infection, both to the T-cell-independent antigen LPS and to the T-cell-dependent antigen CTB. No significant corresponding elevations in plasma IgM antibodies or circulating IgM antibody-secreting cells to CTB were detected. In 17 subjects followed to day 90 after Infection, significant persistence of elevated IgM memory responses was not observed. The IgM memory response to CTB was negatively correlated with the IgG plasma antibody response to CTB, and there was a trend toward negative correlation between the IgM memory and IgA plasma antibody responses to LPS. We did not observe an association between the IgM memory response to LPS and the vibriocidal titer.

PLoS One. 2009; 4(10): e7552
Tariq M, Memon M, Jafferani A, Shoukat S, Gowani SA, Nusrat R, Riaz M, Patel J, Jamil B, Smego RA

BACKGROUND: Cholera is an important infectious cause of secretory diarrhea. The primary symptom of Infection is the sudden onset of watery diarrhea with subsequent volume depletion causing renal insufficiency. The objective of this research is to study the level of dehydration at presentation and subsequent fluid management in patients with Cholera. METHODS: This study was conducted on 191 patients of Cholera admitted at a tertiary care hospital in Karachi, Pakistan during the period of 5 years. Medical charts were evaluated retrospectively for initial hydration status, baseline lab investigations on admission and discharge and fluid therapy given to all the patients while their stay in the hospital and the data was analyzed on SPSS 15.0. RESULTS: Out of the 191 patients, 83(43%) were males and 108 (57%) were females with mean age of 42.3 years (SD+/-18.34). The average duration of symptoms was 3.75 days (SD+/-2.04). Of 191 patients, 175 (92.1%) presented with dehydration, 80 (42.3%) were given Ringer's Lactate (R/L) + Normal Saline (N/S), 45 (24%) patients were given R/L + N/S + Oral Rehydration Therapy (ORS), 27 (14.3%) of the patients were kept on R/L only and remaining were given various combinations of R/L, N/S, ORS and Dextrose Saline (D/S). On admission mean Blood Urea Nitrogen (BUN) was 24.54 (SD+/-16.6), mean creatinine was 2.47 (SD+/-2.35) and mean BUN/Creatinine ratio was 11.63 (SD+/-5.7). CONCLUSION: Aggressive fluid rehydration remains the cornerstone of management of Cholera. Instead of presenting with a classical BUN/Creatinine ratio of >20:1, patients with pre-renal failure in Cholera may present with a BUN/Creatinine ratio of <15:1.

Biochem Biophys Res Commun. 2009 Oct 21;
Zhang T, Hashizume T, Kurita-Ochiai T, Yamamoto M

In this study, we demonstrated that the 40-kDa outer membrane protein of Porphyromonas gingivalis (40k-OMP) sublingually administered with a cDNA vector plasmid encoding Flt3 ligand (pFL) elicited a protective immune response. Sublingual immunization of mice with 40k-OMP plus pFL induced significant serum IgG and IgA, as well as salivary IgA, antibody responses that were comparable to those induced by 40k-OMP plus Cholera toxin as adjuvant. When the subclasses of 40k-OMP-specific IgG were evaluated, sublingual immunization with 40k-OMP plus pFL induced both IgG1 and IgG2a antibody responses. Sublingual delivery of pFL resulted in FL expression in submandibular glands, but not in other oral tissues. Furthermore, marked increases in FL protein occurred in saliva and serum, and the frequencies of both CD11c(+)CD11b(+) and CD11c(+)CD8alpha(+) dendritic cells with up-regulated expression of CD80, CD86 and CD40 molecules significantly increased in submandibular lymph nodes and spleen. Importantly, the mice given sublingual 40k-OMP plus pFL showed a significant reduction of alveolar bone loss caused by oral Infection with P. gingivalis. These findings suggest that sublingual administration of 40k-OMP with pFL acts as an effective and safe mucosal vaccine against oral P. gingivalis Infection, and may be a useful tool in the prevention of chronic periodontitis.

Clin Infect Dis. 2009 Nov 15; 49(10): 1473-9
Weil AA, Khan AI, Chowdhury F, Larocque RC, Faruque AS, Ryan ET, Calderwood SB, Qadri F, Harris JB

BACKGROUND: Multiple Vibrio Cholerae Infections in the same household are common. The objective of this study was to examine the incidence of V. Cholerae Infection and associated clinical symptoms in household contacts of patients with Cholera and to identify risk factors for development of severe dehydration in this cohort. METHODS: Household contacts of hospitalized patients with Cholera were observed with frequent clinical assessments and collection of serum and rectal swab samples for culture for a period of 21 days after presentation of the index case. RESULTS: One-half (460 of 944) of all contacts reported diarrhea during the study period, and symptoms most frequently began 2 days after presentation of the index case. Antibiotics were used by 199 (43%) of 460 contacts with diarrhea. Results of rectal swab cultures for V. Cholerae were positive for 202 (21%) of 944 contacts, and 148 (73%) infected contacts experienced diarrhea. Significant dehydration developed in 26 contacts; predictors of dehydration included vomiting, each additional day of diarrhea, and blood group O status. CONCLUSIONS: In urban Bangladesh, the burden of diarrheal illness among household contacts of patients with Cholera is higher than was previously estimated, and prophylactic intervention is feasible, because the majority of symptomatic cases of V. Cholerae Infection in contacts begin soon after presentation of the index case. Re-evaluation of targeted chemoprophylaxis for household contacts of patients with Cholera may be warranted.

Parasitology. 2009 Oct 16; 1-12
Debache K, Guionaud C, Alaeddine F, Hemphill A

SUMMARYRecombinant NcPDI(recNcPDI), NcROP2(recNcROP2), and NcMAG1(recNcMAG1) were expressed in Escherichia coli and purified, and evaluated as potential vaccine candidates by employing the C57Bl/6 mouse cerebral Infection model. Intraperitoneal application of these proteins suspended in saponin adjuvants lead to protection against disease in 50% and 70% of mice vaccinated with recNcMAG1 and recNcROP2, respectively, while only 20% of mice vaccinated with recNcPDI remained without clinical signs. In contrast, a 90% protection rate was achieved following intra-nasal vaccination with recNcPDI emulsified in Cholera toxin. Only 1 mouse vaccinated intra-nasally with recNcMAG1 survived the challenge Infection, and protection achieved with intra-nasally applied recNcROP2 was at 60%. Determination of cerebral parasite burdens by real-time PCR showed that these were significantly reduced only in recNcROP2-vaccinated animals (following intraperitoneal and intra-nasal application) and in recNcPDI-vaccinated mice (intra-nasal application only). Quantification of viable tachyzoites in brain tissue of intra-nasally vaccinated mice showed that immunization with recNcPDI resulted in significantly decreased numbers of live parasites. These data show that, besides the nature of the antigen, the protective effect of vaccination also depends largely on the route of antigen delivery. In the case of recNcPDI, the intra-nasal route provides a platform to generate a highly protective immune response.

Curr Top Microbiol Immunol. 2009; 337: 37-59
Ritchie JM, Waldor MK

Vibrio Cholerae is a curved Gram-negative rod that causes the diarrheal disease Cholera. One hundred and twenty five years of study of V. Cholerae microbiology have made this lethal pathogen arguably the most well-understood non-invasive mucosal pathogen. Over the past 25 years, modern molecular techniques have permitted the identification of many genes and cellular processes that are critical for V. Cholerae colonization of the gastrointestinal tract. Review of the literature reveals that there are two classes of genes that influence V. Cholerae colonization of the suckling mouse intestine, the most commonly used animal model to study V. Cholerae pathogenesis. Inactivation of one class of genes results in profound attenuation of V. Cholerae intestinal colonization, whereas inactivation of the other class of genes results in only moderate colonization defects. The latter class of genes suggests that V. Cholerae may colonize several intestinal niches that impose distinct requirements and biological challenges, thus raising the possibility that there is physiologic heterogeneity among the infecting population. Efficient V. Cholerae intestinal colonization and subsequent dissemination to the environment appears to require temporally ordered expression of sets of genes during the course of Infection. Key challenges for future investigations of V. Cholerae pathogenicity will be to assess the degree of heterogeneity in the infecting population, whether such heterogeneity has functional significance, and if stochastic processes contribute to generation of heterogeneity in vivo.

PLoS One. 2009; 4(10): e7352
Olivier V, Queen J, Satchell KJ

Vibrio Cholerae colonizes the small intestine of adult C57BL/6 mice. In this study, the physical and genetic parameters that facilitate this colonization were investigated. Successful colonization was found to depend upon anesthesia with ketamine-xylazine and neutralization of stomach acid with sodium bicarbonate, but not streptomycin treatment. A variety of common mouse strains were colonized by O1, O139, and non-O1/non-O139 strains. All combinations of mutants in the genes for hemolysin, the multifunctional, autoprocessing RTX toxin (MARTX), and hemagglutinin/protease were assessed, and it was found that hemolysin and MARTX are each sufficient for colonization after a low dose Infection. Overall, this study suggests that, after intragastric inoculation, V. Cholerae encounters barriers to Infection including an acidic environment and an immediate immune response that is circumvented by sodium bicarbonate and the anti-inflammatory effects of ketamine-xylazine. After initial adherence in the small intestine, the bacteria are subjected to additional clearance mechanisms that are evaded by the independent toxic action of hemolysin or MARTX. Once colonization is established, it is suggested that, in humans, these now persisting bacteria initiate synthesis of the major virulence factors to cause Cholera disease. This adult mouse model of intestinal V. Cholerae Infection, now well-characterized and fully optimized, should serve as a valuable tool for studies of pathogenesis and testing vaccine efficacy.

Vaccine. 2009 Nov 23; 27(50): 6983-90
Hickey DK, Aldwell FE, Tan ZY, Bao S, Beagley KW

The development of vaccines to combat pathogens that infect across mucosal surfaces has been a major goal of vaccine research. Successful mucosal vaccination requires the co-administration of adjuvants that can overcome the state of immune tolerance normally associated with mucosal application of proteins. In the case of oral immunization, delivery systems are also required to protect vaccine antigens against destruction by gastric pH and digestive enzymes. Furthermore, adjuvants used for mucosal delivery must be free of neurotoxic effects like those induced by the commonly used experimental mucosal adjuvant Cholera toxin. Maintenance of the "cold chain" is also essential for the effectiveness of any vaccine and adjuvants/delivery systems that enhance the stability of a vaccine would offer a significant advantage. Needle-free methods of vaccination that induce protective immunity at multiple mucosal surfaces are also desirable for rapid vaccination of large populations. In the present study we show that transcutaneous immunization (TCI) using Lipid C, a novel lipid-based matrix originally developed for oral immunization, containing soluble Helicobacter sonicate significantly reduces the gastric bacterial burden in mice following gastric challenge with live Helicobacter pylori. Protection is associated with the production of splenic gamma interferon and gastric IgA and was achieved without the co-administration of potent and potentially toxic adjuvants, although protection was further enhanced by inclusion of CpG-ODN and Cholera toxin in the lipid delivery system.

Microbes Infect. 2009 Sep 24;
Hong W, Peng D, Rivera M, Gu XX

Otitis media (OM) can occur following outset of upper respiratory tract Infections. Inhibition of bacterial colonization in nasopharynx (NP) by mucosal vaccination may prevent OM by reducing bacterial invasion of the middle ears (MEs). In this study, 80 chinchillas were intranasally (i.n.) immunized with a detoxified lipooligosaccharide (dLOS)-tetanus toxoid conjugate vaccine of nontypeable Haemophilus influenzae (NTHi) mixed with Cholera toxin (CT) or CT alone. All vaccinated animals responded with elevated levels of mucosal and serum anti-LOS antibodies. Two weeks after the last immunization, 40 chinchillas were challenged i.n. with NTHi to evaluate NP colonization and ME Infection while the rest of the animals were challenged transbullarly (T.B.) to examine the development of OM. Compared to the control group, the vaccination inhibited not only bacterial colonization in NP and transmission to MEs in the i.n. challenge group but also bacterial colonization in NP and transmission to unchallenged ears in the T.B. challenge group. Though no difference was found in the challenged ears of either group right after the T.B. challenge, an early clearance of NTHi from NP and unchallenged ears as well as less severity of OM in the unchallenged ears were observed in vaccinated animals. Current results along with our previous data indicate that mucosal vaccination is capable of inhibiting NTHi NP colonization and preventing OM occurrence in chinchillas; the i.n. challenge model is preferable for testing the mucosal vaccines while the T.B. challenge model is superior for testing the systemic vaccines.

Macromol Biosci. 2009 Sep 24;
Maheshwari R, Levenson EA, Kiick KL

Multivalent, glycopolymer inhibitors designed for the treatment of disease and pathogen Infection have shown improvements in binding correlated with general changes in glycopolymer architecture and composition. We have previously demonstrated that control of glycopolypeptide backbone extension and ligand spacing significantly impacts the inhibition of the Cholera toxin B subunit pentamer (CT B(5)) by these polymers. In the studies reported here, we elucidate the role of backbone charge and linker length in modulating the inhibition event. Peptides of the sequence AXPXG (where X is a positive, neutral or negative amino acid), equipped with the alkyne functionality of propargyl glycine, were designed and synthesized via solid-phase peptide synthetic methods and glycosylated via Cu(I)-catalyzed alkyne-azide cycloaddition reactions. The capacity of the glycopeptides to inhibit the binding of the B(5) subunit of Cholera toxin was evaluated. These studies indicated that glycopeptides with a negatively charged backbone show improved inhibition of the binding event relative to the other glycopeptides. In addition, variations in the length of the linker between the peptide and the saccharide ligand also affected the inhibition of CT by the glycopeptides. Our findings suggest that, apart from appropriate saccharide spacing and polypeptide chain extension, saccharide linker conformation and the systematic placement of charges on the polypeptide backbone are also significant variables that can be tuned to improve the inhibitory potencies of glycopolypeptide-based multivalent inhibitors.

Infect Immun. 2009 Dec; 77(12): 5496-500
Arakawa T, Tachibana M, Miyata T, Harakuni T, Kohama H, Matsumoto Y, Tsuji N, Hisaeda H, Stowers A, Torii M, Tsuboi T

Malaria vaccines based on ookinete surface proteins (OSPs) of the malaria parasites block oocyst development in feeding mosquitoes and hence disrupt the parasite life cycle and prevent the disease from being transmitted to other individuals. To investigate whether a noninvasive mucosal vaccination regimen effectively blocks parasite transmission in vivo, Plasmodium yoelii Pys25, a homolog of the Pfs25 and Pvs25 OSPs of Plasmodium falciparum and Plasmodium vivax, respectively, was intranasally (i.n.) administered using a complement-deficient DBA/2 mouse malaria Infection model, in which a highly elevated level of oocysts develops in feeding mosquitoes. Vaccinated mice developed a robust antibody response when the vaccine antigen was given together with Cholera toxin adjuvant. The induced immune serum was passively transferred to DBA/2 mice 3 days after Infection with P. yoelii 17XL, and Anopheles stephensi mosquitoes were allowed to feed on the infected mice before or after serum transfusion. This passive immunization completely blocked oocyst development; however, immune serum induced by the antigen or adjuvant alone did not have such a profound antiparasite effect. Further, when i.n. vaccinated mice were infected with the parasite and then mosquitoes were allowed to directly feed on the infected mice, complete blockage of transmission was again observed. To our knowledge, this is the first time that mucosal vaccination has been demonstrated to be efficacious for directly preventing parasite transmission from vaccinated animals to mosquitoes, and the results may provide important insight into rational design of nonparenteral vaccines for use against human malaria.

J Bacteriol. 2009 Nov; 191(21): 6632-42
Pratt JT, McDonough E, Camilli A

Signaling through the second messenger cyclic di-GMP (c-di-GMP) is central to the life cycle of Vibrio Cholerae. However, relatively little is known about the signaling mechanism, including the specific external stimuli that regulate c-di-GMP concentration. Here, we show that the phosphate responsive regulator PhoB regulates an operon, acgAB, which encodes c-di-GMP metabolic enzymes. We show that induction of acgAB by PhoB positively regulates V. Cholerae motility in vitro and that PhoB regulates expression of acgAB at late stages during V. Cholerae Infection in the infant mouse small intestine. These data support a model whereby PhoB becomes activated at a late stage of Infection in preparation for dissemination of V. Cholerae to the aquatic environment and suggest that the concentration of exogenous phosphate may become limited at late stages of Infection.

FEMS Immunol Med Microbiol. 2009 Nov; 57(2): 136-41
Bhuiyan NA, Nusrin S, Alam M, Morita M, Watanabe H, Ramamurthy T, Cravioto A, Nair GB

We determined the genotype of Cholera toxin by amplifying and sequencing the B-subunit in a sequential collection of 90 strains of Vibrio Cholerae O139 isolated over the past 13 years since its first description in 1992. Representative strains isolated during 1993-1997 harboured ctxB of El Tor type (genotype 3). Twenty-six strains isolated during 1999, 2001, 2005 and three strains isolated in 1998, 2000 and 2002 were identified to belong to new ctxB genotypes 4 and 5, respectively. Genotype 5 was similar to genotype 1 except at position 28 (D-->A). The genotype 6 was similar to genotype 4 except at position 34 (H-->P). The implication of switch in terms of function of the toxin and its impact on human disease is unclear. How this change has influenced their prevalence relative to that of V. Cholerae O1 in human Infection is also not clear. The other common virulence gene clusters including the Vibrio pathogenicity island-1, Vibrio seventh pandemic island (VSP)-I and VSP-II of V. Cholerae O139 did not show any remarkable difference from that of the O1 El Tor strains. Overall, the majority of the O139 strains tested in this study were similar to the El Tor strains but had altered ctxB genotype. This change and the impact that it causes to the epidemiology of Cholera caused by O139 should be closely monitored.

Microbiol Immunol. 2009 Apr; 53(4): 233-40
Scavone P, Rial A, Umpierrez A, Chabalgoity A, Zunino P

Proteus mirabilis is commonly associated with complicated UTI and expresses several virulence factors, including MR/P fimbriae. In the present study mice were immunised nasally with MrpA, the structural subunit of MR/P, with or without CT as a mucosal adjuvant. The animals were then challenged with P. mirabilis and induction of specific serum and urine IgG and IgA, IFN-gamma production and bacterial kidney and bladder colonization were assessed. MrpA-immunised mice exhibited significant induction of serum IgA and urine IgA and IgG. MrpA/CT-immunised mice showed both significant serum and urine IgA and IgG production. Only this group showed significant IFN-y production. Both groups of animals had significant decrease in bacterial colonization of kidneys but not of bladders. No correlation between specific antibody induction in serum and CFU decrease was observed in any group of animals. Our results suggest that a mucosal adjuvant (CT) in the urinary tract enhanced humoral and cytokine response although it did not influence the degree of protection against UTI provided by MrpA. Further studies are necessary to understand immune modulation in the urinary tract.

J Med Microbiol. 2009 Dec; 58(Pt 12): 1616-22
Agrawal AS, Sarkar M, Chakrabarti S, Rajendran K, Kaur H, Mishra AC, Chatterjee MK, Naik TN, Chadha MS, Chawla-Sarkar M

Acute respiratory tract Infections (ARTIs) are one of the most common causes of morbidity and mortality in young children worldwide. Influenza virus and respiratory syncytial virus (RSV) are the predominant aetiological agents during seasonal epidemics, and thus rapid and sensitive molecular tests for screening for such agents and timely identification of epidemics are required. This study compared real-time quantitative PCR (qPCR) with conventional RT-PCR for parallel identification of influenza A virus (IAV) or influenza B virus (IBV) and RSV. A total of 1091 respiratory samples was examined from children with suspected ARTIs between January 2007 and December 2008. Of these, 275 (25.21 %) were positive for either influenza or RSV by qPCR compared with 262 (24 .01%) positive by RT-PCR. Overall, IAV, IBV and RSV were detected in 121 (11.09 %), 59 (5.41 %) and 95 (8.71 %) samples, respectively. In spite of overlapping clinical symptoms, RSV and influenza virus showed distinct seasonal peaks. IAV correlated positively and RSV negatively with rainfall and temperature. No distinct seasonality was observed in IBV Infections. This is, to the best of our knowledge, the first report of a systemic surveillance of respiratory viruses with seasonal correlation and prevalence rates from eastern India. This 2 year comparative analysis also confirmed the feasibility of using qPCR in developing countries, which will not only improve the scope for prevention of epidemics, but will also provide crucial epidemiological data from tropical regions.

Commun Integr Biol. 2008 Jul; 1(1): 42-4
Tsou AM, Frey EM, Hsiao A, Liu Z, Zhu J

Pathogenic bacteria, such as Vibrio Cholerae, must be capable of adapting to diverse living conditions, especially when transitioning from life in environmental reservoirs to life in a host. The abilities to sense arrival at a site suitable for colonization or Infection and to respond with appropriate alterations in gene expression are crucial for a pathogen's success. Recently, we have shown that V. Cholerae is able to recognize that it has reached its colonization site in the small intestine by sensing breakage of its flagellum as it penetrates the mucosal layer overlaying the intestinal epithelium. Flagellar loss results in the release of the anti-sigma factor FlgM and subsequent activation of the alternative sigma-factor FliA. FliA represses the quorum sensing-controlled transcriptional regulator, HapR, allowing increased expression of virulence factors such as Cholera Toxin (CT) and the Toxin Coregulated Pilus (TCP). In this way, the de-repression of virulence factor expression coincides with the arrival of bacteria at the site of Infection at the intestinal mucosa. Our work reveals an interesting interplay between motility and quorum sensing signaling pathways to precisely time virulence gene expression during colonization.