Experimental Research On The Antibody Expression Spectrum Of Yersinia Pestis Virulence-associated Proteins Using Protein Microarray

Plague is an ancient disease which has caused over 160 million human deaths in the past and has not been eradicated from the modern world. The etiological agent of plague is Yersinia pestis. Y. pestis is one of ll species of the genus Yersinia. Three members of the genus are pathogenic to humans: Y.pestis, Y. pseudotuberculosis and Y. enterocolitica.Plague is usually contracted by human as a result of the bite of an infected flea. Each year there are several thousand reported cases of the disease world-wide and plague has been classified as a re-emerging disease by the World Health Organization. Endemic areas for the disease exist in China, Africa, Asia and South America. The Surat outbreak of plague in India in 1994 reminded the world of the threat of this horrible disease. Plague is an international public health risk and a notifiable disease. More over, Y. pestis has been of concern as one of the microorganisms which might be used illegitimately as a bioterrorisim agent against civilian or military communities.Because of the increasing plague casers and the likelihood of illegitimate use of Y. pestis, there is a requirement for an effective vaccine which can protect human against both bubonic and pneumonic plague.There are two kinds of vaccines have been used in human, live attenuated vaccine and killed whole cells vaccine (KWC) .The earliest report of a killed whole cell vaccine against plague was in 1897, and USP (a KWC vaccine) had been used in Vietnam during the period 1961-1971. But recent studies in animals have shown that this vaccine offers poor protection against pneumonic disease. Another vaccine, live attenuated vaccine ( EV76 strain) , has been in use since 1908, and was used hi many countries in the late 20 century. However, as EV76 is not fully avirulent, the safety of this vaccine in human is questionable. Today EV76 is considered unsuitable for humans in most countries. The efficacy and the safety of existing vaccines are not proven, and the use of these vaccines is known to be associated with adverse side effects.-7-Therefore there is an urgent need for an more efficacious plague vaccine.In recent years, efforts have focused on the development of a fully recombinant subunit vaccine for plague and the identification of a rationally attenuated mutant strain of Y. pestis.Theoretically speaking, any bacterial antigen exposed to the immune system represents a potential vaccine candidate. Anyway, only a few antigens can be analyzed simultaneously using conventional approach, and if negative results were obtained from in vitro and in vivo models, the process must repeated from the beginning, which often costs several years to get an ideal result.in the post-genomics era, three new strategies have been used to identify vaccine candidates. The three strategies share the same four basic steps: (1) selection of a set of genes from the whole genome; (2) high throughput cloning and expression of the selected genes; (3 ) purification of the recombinant proteins; and (4) in vitro and in vivo assays for identification of candidates.The virulence-associated genes selection is considered to be an important step in vaccine discovery. The three strategies differ in the way to select virulence-associated genes. According to the first strategy, genes are selected in silico utilizing algorithms that can predict genes encoding secreted and surface-associated antigens and virulence factors. These proteins are considered the most relevant for the induction of a protective immune response. Using the second approach, surface-exposed antigens are selected experimentally through the characterization of protein fractions using proteomics techniques such as two-dimensional gel electrophoresis (2D-GE) and mass spectrometry. The third approach is aimed at the identification of invasion and virulence-associated antigens and makes use of several new technologies including in vivo expression technology (IVET), signature-tagged mutagenesis ( STM) and DNA microarray technology.Protein microarray analysis offers a se...