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Kothari, Sudeep,Kim, Jeong-Ah,Kothari, Neha,Jones, Christopher,Choe, Woo Seok,Carbis, Rodney Elsevier 2014 Vaccine Vol.32 No.21
The O specific polysaccharide (OSP) of the lipopolysaccharide (LPS) of Salmonella enterica serovar Paratyphi A is a protective antigen and the target for vaccine development. LPS is the major constituent of the outer membrane of S. Paratyphi A with the OSP exposed on the surface, in addition to the cell associated LPS a large amount of free LPS was present in the fermentation broth. A purification method was developed to take advantage of both sources of LPS and to maximize recovery of OSP. After fermentation the bacterial cells were concentrated and washed, the permeate containing the free LPS was processed separately from the cells. The free LPS was concentrated and washed on a 100 kD ultrafiltration membrane to remove low molecular weight impurities. The LPS was then detoxified by separation of the lipid A from the OSP using acid hydrolysis at 100 degrees C, the precipitated lipid A was removed by 0.2 mu m membrane filtration. Contaminants were then removed by acid precipitation in the presence of sodium deoxycholate. The OSP was concentrated and washed with 1 M NaCl then water using a 10 kD ultrafiltration membrane then sterile filtered through a 0.2 mu m membrane filter. The cells were treated by acid hydrolysis at 100 degrees C, the remaining cells, cell debris and precipitate was removed by centrifugation. The filtrate was then treated in the same way as described above for the free LPS. The combined yield of purified OSP from free LPS plus the cells was greater than 880 mg/L of culture broth. The method developed yields large amounts of OSP, is scalable and compatible with cGMP so would be readily transferrable to developing country vaccine manufacturers for low cost production of vaccine against S. Paratyphi A. (C) 2014 Elsevier Ltd. All rights reserved.
Ali, Aamir,An, So J,Cui, Changfa,Haque, Abdul,Carbis, Rodney Landes Bioscience 2014 Human Vaccines & Immunotherapeutics Vol.10 No.6
<P>Salmonella enterica serovar Paratyphi A (S. Paratyphi A) is a human restricted pathogen that can cause systemic infection (paratyphoid fever) with recently increased incidence particularly in developing countries. Currently there is no licensed vaccine for prevention of infection from S. Paratyphi A. In this study the O-specific polysaccharide (OSP) of S. Paratyphi A was conjugated to diphtheria toxoid (DT) with and without adipic acid dihydrazide (ADH) as a linker. Binding of the OSP to a carrier protein was intended to convert a T-cell independent OSP response to a T-cell dependent response inducing higher levels of anti-OSP antibodies and immunological memory. These conjugates (OSP-AH-DT and OSP-DT) were evaluated for their immunogenicity in mice. The S. Paratyphi A OSP-DT conjugate induced a poor anti-OSP response less than that observed with LPS while the OSP-AH-DT conjugate induced a significantly higher antibody titer compared with LPS alone. The study also demonstrated diphtheria toxoid as a potential carrier protein for conjugate vaccine candidates using S. Paratyphi A OSP.</P>
( Hyun Jang ),( Hyo Seung Kim ),( Jeong Ah Kim ),( Jin Ho Seo ),( Rodney Carbis ) 한국미생물 · 생명공학회 2009 Journal of microbiology and biotechnology Vol.19 No.1
A simplified method for the purification of cholera toxin was developed. The 569B strain of Vibrio cholerae, a recognized hyper-producer of cholera toxin, was propagated in a bioreactor under conditions that promote the production of the toxin. The toxin was separated from the bacterial cells using 0.2-μm crossflow microfiltration, the clarified toxin was passed through the membrane into the permeate, and the bacterial cells were retained in the retentate. The 0.2-μm permeate was then concentrated 3-fold and diafiltered against 10 mM phosphate buffer; pH7.6, using 30-kDa crossflow ultrafiltration. The concentrated toxin was loaded onto a cation exchange column, the toxin was bound to the column, and most of the impurities were passed unimpeded through the column. The toxin was eluted with a salt gradient of phosphate buffer, pH7.0, containing 1.0M NaCl. The peak containing the toxin was assayed for cholera toxin and protein and the purity was determined to be 92%. The toxin peak had a low endotoxin level of 3.1 EU/μg of toxin. The purified toxin was used to prepare antiserum against whole toxin, which was used in a GM1 ganglioside-binding ELISA to determine residual levels of toxin in an oral inactivated whole-cell cholera vaccine. The GM1 ganglioside-binding ELISA was shown to be very sensitive and capable of detecting as little as 1 ng/ml of cholera toxin.