Analysis of IL-4 promoter and VNTR polymorphisms in Thai patients with pulmonary tuberculosis

@#Tuberculosis (TB) is a leading cause of morbidity and mortality in Thailand. Cytokines play important roles in defense against Mycobacterium tuberculosis infection. Interleukin (IL)-4 is one of the anti-inflammatory cytokines and has been found to be elevated in TB patients. The common polymorphisms in IL-4 gene, including IL-4-590C/T, IL-4-33C/T, and IL-4-variable number of tandem repeats (VNTR) intron 3 have been reported to be associated with risk for some diseases. The purpose of this study was to investigate possible associations between the above mentioned three common functional polymorphisms in the IL-4 gene in patients with pulmonary tuberculosis (PTB) in a Thai population. Forty three patients with PTB and 90 healthy control subjects were studied. The three common polymorphisms of the IL-4 gene were determined using polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (PCR-RFLP). The allele and genotype frequencies of IL-4 -590 C/T, -33 C/T, VNTR intron 3 polymorphisms did not show significant differences between PTB patients and healthy controls (genotype: p=0.88, p=0.92, p=0.40; allele: p=0.38, p=0.44, p=0.53, respectively). However, the allele distribution of the IL-4 -590 C, -33 C, and VNTR R3 was higher among PTB patients (25.58%, 25.58%, 25.58%, respectively) than among control subjects (20%, 20.48%, 19.44%, respectively). This may suggest that IL-4-590C/T, -33C/T and VNTR intron 3 might play a role in susceptibility to PTB. A larger cohort may possibly help conclude our findings.

Production of specific monoclonal antibodies to Burkholderia pseudomallei and their diagnostic application.

Hybridomas secreting monoclonal antibodies (MAbs) specific to Burkholderia pseudomallei were produced by immunizing BALB/cJ mice with crude culture filtrate of B. pseudomallei. Two monoclonal antibodies were found to be highly specific to B.pseudomallei as tested by indirect enzyme-linked immunosorbent assay and immunoblotting against a panel of crude whole cell extracts from B. pseudomallei, B. cepacia, Pseudomonas aeruginosa, P.putida, and Escherichia coli. One of the specific MAbs, clone SP-M, IgM subclass, could directly agglutinate all 42 B. pseudomallei, isolates. The study has shown that the agglutinating MAb has potential for rapid identification of B. pseudomallei in primary bacterial culture from clinical specimens. The antibody can be used in bacteriology laboratories to reduce time of biochemical methods, which require a few days.

Monoclonal antibodies against protein antigens of salmonellae causing paratyphoid fever and their diagnostic application.

Hybrid clones producing monoclonal antibodies (MAbs) specific for Salmonella paratyphi A (72 clones), S. paratyphi B (9 clones) and S. paratyphi C (8 clones) were produced by using the affinity purified Salmonella protein (Bp) as immunogens. MAbs to S. paratyphi A and S. paratyphi B reacted specifically with the 52 kDa homologous flagellin protein components while those to S. paratyphi C reacted with a 61 kDa flagellin protein component. The MAbs against S. paratyphi A and S. paratyphi B were used to establish a double antibody sandwich ELISA for detection of the 52 kDa flagellin antigens in serum samples from patients with acute paratyphoid A and paratyphoid B fever. With this assay system, 6.25 ng per ml of flagellin antigens of S. paratyphi A and S. paratyphi B could be detected. However, the assay system could not detect the flagellin antigens in patients' sera. The presence of IgM antibodies to the 52 kDa antigens of S. paratyphi A and S. paratyphi B in the acute sera from paratyphoid A or paratyphoid B patients suggested that the 52 kDa protein components of both salmonellae are good immunogens for human and might be used as antigens for early diagnosis of paratyphoid A and paratyphoid B fever.

Molecular cloning and expression of Salmonella paratyphi A 52 kDa specific protein gene.

Monoclonal antibodies (MAbs) specific to Salmonella paratyphi A have been established by our group in 1989. These MAbs were proven to be species-specific for 52 kDa protein of S. paratyphi A but the nature of this protein is unknown. However, our group have proved that the 52 kDa protein which is specific to S. typhi was flagellin. This present study has characterized the 52 kDa protein of S. paratyphi A and identified its encoded gene. The plasmid containing the specific 52 kDa antigen gene was cloned from the S. paratyphi A genome, herein designated pSKA-4. Partial nucleotide sequences from this clone was analysed by computer program and found to be phase 1-a flagellin gene of S. paratyphi A. In addition, the nucleotide sequence analysis from such clone also showed that the structural gene for phase 1 flagellin has amino acid sequences conserved at the terminal whereas the central region is variable among Salmonella spp. Therefore, the central portion of flagellin which highly polymorphic in amino acid sequences would be the most specific to S. paratyphi A, thus, should be used as specific antigen for developing specific diagnosis of S. paratyphi A infection. Using the PCR technique, an expression plasmid containing the antigen gene producing only the variable region in the central portion of flagellin from S. paratyphi A, namely pSKA-7, has been established. The recombinant protein produced by the established plasmid has a MW 33.5 kDa as detected by immunoblotting using specific MAbs. Further study by using this specific flagellin protein for immunodiagnosis of S. paratyphi A infection is being carried out in our laboratory.

Production of monoclonal antibodies to Vi polysaccharide antigen of Salmonella typhi.

Twenty-four Vi antigen-specific monoclonal antibodies were produced in this study. The MAbs were found to be highly specific to Vi possessing bacteria. Selected MAbs were used in a direct agglutination assay for rapid identification of S. typhi in primary bacterial culture and also used to develop an assay to detect Vi antigen in clinical specimens. The result showed that they could not detect the antigen in urine and serum from acute patients even they could detect as low as 0.02 micrograms/ml of Vi antigen added in normal urine. The study has shown that these MAbs are very useful for rapid identification of S. typhi in primary bacterial culture and they can replace polyclonal anti-Vi antibodies which have been used routinely in bacteriological laboratories.

Molecular cloning and expression of Salmonella typhi flagellin: characterization of 52 kDa specific antigen of S. typhi.

We previously reported monoclonal antibodies (MAbs) specific to S. typhi 52 kDa antigen which do not cross react with related protein antigens from 11 bacteria causing enteric fever and enteric fever-like illness. Using the combination of these specific MAbs and recombinant DNA technology, expression plasmids containing the antigen gene producing substantial amount of the S. typhi protein antigen have been established. Plasmid pSKM-T7 containing the specific 52 kDa antigen gene was cloned and the antigen expressed was detectable by immunoblotting using specific mAbs. The complete nucleotide sequence of this gene was compared with other bacterial sequences and found to be highly homologous with the flagellin gene H1-d of S. muenchen except in the hypervariable region in the central portion. The specific 52 kDa antigen of S. typhi detected by our MAbs is thus a flagellin.