Quorum Sensing Regulation of the Two hcp Alleles in Vibrio cholerae O1 Strains

BACKGROUND: The type VI secretion system (T6SS) has emerged as a protein secretion system important to several gram-negative bacterial species. One of the common components of the system is Hcp, initially described as a hemolysin co-regulated protein in a serotype O17 strain of Vibrio cholerae. Homologs to V. cholerae hcp genes have been found in all characterized type VI secretion systems and they are present also in the serotype O1 strains of V. cholerae that are the cause of cholera diseases but seemed to have non-functional T6SS. METHODOLOGY/PRINCIPAL FINDINGS: The serotype O1 V. cholerae strain A1552 was shown to express detectable levels of Hcp as determined by immunoblot analyses using polyclonal anti-Hcp antiserum. We found that the expression of Hcp was growth phase dependent. The levels of Hcp in quorum sensing deficient mutants of V. cholerae were compared with the levels in wild type V. cholerae O1 strain A1552. The expression of Hcp was positively and negatively regulated by the quorum sensing regulators HapR and LuxO, respectively. In addition, we observed that expression of Hcp was dependent on the cAMP-CRP global transcriptional regulatory complex and required the RpoN sigma factor. CONCLUSION/SIGNIFICANCE: Our results show that serotype O1 strains of V. cholerae do express Hcp which is regarded as one of the important T6SS components and is one of the secreted substrates in non-O1 non-O139 V. cholerae isolates. We found that expression of Hcp was strictly regulated by the quorum sensing system in the V. cholerae O1 strain. In addition, the expression of Hcp required the alternative sigma factor RpoN and the cAMP-CRP global regulatory complex. Interestingly, the environmental isolates of V. cholerae O1 strains that showed higher levels of the HapR quorum sensing regulator in comparison with our laboratory standard serotype O1 strain A1552 where also expressing higher levels of Hcp

Effectiveness of Obstetric Emergency Workshop in Medical Students in Newcastle University Malaysia

Global practices in health sectors envisioned maternal mortality as an indicator of the health standard of the nation. World Health Organization rests its goal on ‘Eight Millennium Development’ over the globe by means of MDG 5 is to improve the maternal health. The aim of the study is to upgrade teaching and learning method to optimise acquisition of knowledge in undergraduate students to meet the effectiveness of obstetric emergencies. We evaluated changes in knowledge using a single best answers questionnaire. The study 115 stage-5 students from 2019-2020 academic years were selected, and they were divided into 5 small groups with monthly rotation to attend the workshop. There are 23-24 students in each rotation. The assessment of knowledge of obstetrics emergencies carried out by using the SBA test before and after the workshop conducted by means of teaching and learning method

Mapping hypoendemic, seasonal malaria in rural Bandarban, Bangladesh: a prospective surveillance

<p>Abstract</p> <p>Background</p> <p>Until recently the Chittagong Hill tracts have been hyperendemic for malaria. A past cross-sectional RDT based survey in 2007 recorded rates of approximately 15%. This study was designed to understand the present epidemiology of malaria in this region, to monitor and facilitate the uptake of malaria intervention activities of the national malaria programme and to serve as an area for developing new and innovative control strategies for malaria.</p> <p>Methods</p> <p>This research field area was established in two rural unions of Bandarban District of Bangladesh north of Bandarban city, which are known to be endemic for malaria due to <it>Plasmodium falciparum</it>. The project included the following elements: a) a demographic surveillance system including an initial census with updates every four months, b) periodic surveys of knowledge attitude and practice, c) a geographic information system, d) weekly active and continuous passive surveillance for malaria infections using smears, rapid tests and PCR, f) monthly mosquito surveillance, and e) daily weather measures. The programme included both traditional and molecular methods for detecting malaria as well as lab methods for speciating mosquitoes and detecting mosquitoes infected with sporozoites.</p> <p>Results</p> <p>The demographic surveillance enumerated and mapped 20,563 people, 75% of which were tribal non-Bengali. The monthly mosquito surveys identified 22 <it>Anopheles </it>species, eight of which were positive by circumsporozoite ELISA. The annual rate of malaria was close to 1% with 85% of cases in the rainy months of May-October. Definitive clustering identified in the low transmission season persisted during the high transmission season.</p> <p>Conclusion</p> <p>This demographically and geographically defined area, near to the Myanmar border, which is also hypoendemic for malaria, will be useful for future studies of the epidemiology of malaria and for evaluation of strategies for malaria control including new drugs and vaccines.</p