Dissertation > Excellent graduate degree dissertation topics show

Pathogenicity of Human Shigella to Chicken and Comparative Study on Some Important Genes of Chicken and Human Shigella

Author: LiuHongYing
Tutor: WangChuanQing
School: Henan Agricultural University
Course: Preventive Veterinary Medicine
Keywords: Shigella Artificial infection Cohabitation infection Virulence plasmid Plasmid transfer Pathogenicity Quinolone Resistance QRDR
CLC: S852.61
Type: Master's thesis
Year: 2008
Downloads: 60
Quote: 8
Read: Download Dissertation

Abstract

Bacillary dysentery is an acute intestinal infectious disease caused by Shigella, a worldwide epidemic, especially in developing countries, an important public health problem. In addition to infect humans cause dysentery, Shigella can also be caused by a variety of animal infections, the incidence. XU Lan-ju, first discovered in 2004, chicken Shigella infection is not clear, but the relationship with Shigella. Learn more about Shigella especially molecular biological characteristics of chicken abalone Shigella, pathogenic pathogenic molecular mechanisms, in order to ascertain the chicken abalone Shigella sources in terms of public health sense, this paper carried out the following studies and achieve the desired results: 1. treated with different doses of chicken boydii, people boydii and flexneri Shigella bacteria artificially infected by intraperitoneal injection of 1-day-old chicks. Found that both can cause the chicks morbidity and death, and pull Campylobacter typical symptoms. Shigella prove people artificially infected chicks and deaths caused by the disease. Shigella bacteria, different dose of chicks cohabitation infection test results showed 102 bacteria that can cause a 20% incidence chicks. Artificially infected test group, and cohabiting lesions of naturally infected chicks have different levels of the necropsy lesions rate of 100%. Young chickens from each experimental group recovered to the original inoculated strains. Thus proving people Shigella can infect chicks can cause horizontal transmission virulence plasmid, and in this process will not soon be lost. We also found the chicken body can be used as a reservoir host of Shigella, Shigella infection of chickens with similar cases, that is enhanced with increasing age resistance of Shigella infection exist. This study not only the relationship between the chicken Shigella sources and people - chicken Shigella bacteria circumstantial evidence, and proof of the possibility of cross-infection between human and birds. Through 3. Flexneri Shigella virulence plasmid lost the plasmid chicken Shigella vitro, the plasmid can be transferred to the chickens lost their own virulence plasmid of Shigella. Strains with different doses of virulence plasmid transfer by oral and intraperitoneal injection of artificially infected chickens and mice, respectively, the results show that 80% of the the chickens infected highest incidence rate in mice up to 60%; although no deaths, but a necropsy lesions rate of 100%. From the test animals were recovered to the original inoculated. Shigella lost virulence plasmid found in the training process and its cultural characteristics change greatly, regain virulence plasmid is able to recover most of its culture characteristics. The first study found that the transfer Shigella virulence plasmid can be transferred to the in vitro chicken Shigella, and newly generated strains have a certain stability and pathogenicity. The inferred large virulence plasmid and lost virulence plasmid similar pathogens exist in the appropriate external environment, both may occur plasmid transfer, resulting in a new intact pathogenic strains. Detected by susceptibility testing chickens and people boydii Shigella bacteria, people Shigella bacteria resistant to 12 kinds of antibiotics, three Shigella were not found to produce resistance to quinolones . Two pairs of primers designed according to published sequences were amplified gyrA gene and parC genes in three Shigella, and one of the quinolone resistance-determining region (QRDR) for analysis. Found that the sequence of the chicken boydii and human boydii Shigella bacteria QRDR any nucleotide mutations did not happen, which coincide with the susceptibility test results. Shigella bacteria gyrA gene exist 83 Ser83 (TCG) → Leu (TTG) mutations, only the locus of the mutation, so no resistance characterization, and bacterial quinolone class of drug required to agree GyrA and ParC multiple sites mutation or other mechanisms of resistance; parC genes at the same time there are 58 Ser58 (AGC) → Ile (ATC) mutations, the mutations and common 80,84 amino acid change is different, still being in QRDR region. Yet can not be the basis of this result to determine the relationship between the mutation and quinolone resistance, but at least show that the strain is in the process of resistance evolution. Its exact role in the formation of drug resistance in Shigella remains to be further studied. 5. Using PCR technology to get the chicken Shigella boydii ipaH six copies of the gene fragment, and its sequence homology analysis, found that the reported chicken abalone Shigella boydii strains CP001063 homology in six copies of a nucleotide sequence comparison of the fragment is the highest; domestic coverage boydii strains CP000036 homology comparison of the nucleotide sequence of the six copies, although there are differences, but with 5 except ipaH ₂ outside fragment homology after CP001063. This result further shows chicken abalone Shigella boydii originated in the possibility of Shigella. People boydii and Shigella the bacteria's ipaB, and ipaC gene also selected as the research object, its cloning and sequencing analysis. The results show that the boydii Shigella (B strain) ipaB gene with the corresponding sequence homology of 98.3% to 99.9%, the the ipaC gene with the corresponding sequence homology of 97.8% to 100.0% ; people Shigella bacteria (F strain) ipaB gene with the corresponding sequence homology of 98.1% to 99.5%, and 97.9% to 100.0% of ipaC gene with the corresponding sequence homology. These results for future further study the molecular mechanisms of IpaB and IpaC protein expression in Shigella pathogenesis laid the foundation, and if we can get the soluble IpaB and IpaC protein, serialization features and immunological features, and in vitro and in vivo functional studies can better research Shigella pathogenesis. In this study, the Shigella and especially chicken abalone Shigella, of pathogenic their further molecular biology research provides a theoretical basis.

Related Dissertations

CLC: > Agricultural Sciences > Livestock, animal medicine,hunting,silkworm,bee > Animal Medicine ( Veterinary Medicine) > Basic Veterinary Science > Animal Microbiology ( Veterinary Microbiology, ) > Pathogenic bacteria
© 2012 www.DissertationTopic.Net Mobile