Abstract:
Cell mediated immunity is an important part of host defence. Nitric oxide has an
antimicrobial activity and play an important role against variety of bacteria including
B. melitensis. This study aimed to evaluate the immunoreactivity of fractionated
lipopolysaccharide (LPS) antigen of B. melitensis in cell culture. The LPS antigen was
fractionated by gel filtration chromatography. The lymphoproliferation was estimated
with 3-(4,5-dimethyl thiozol-2yl)-2,5 diphenyl tetrazolium bromide (MTT) colorimetric
method. After comparing all the LPS antigen fractions which were fractionated by gel
filtration chromatography, it was observed that LPG1 induced maximum lymphocyte
proliferation in-vitro, followed by LPG2, LPG5, LPG4 and then LPG3 respectively.
Nitric oxide (NO) production by the monocyte-derived macrophages on stimulation
with LPS antigen of B. melitensis was assessed using a colorimetric assay for nitrite
based on Griess reaction. It was observed that LPG1 produce maximum nitrite followed
by LPG2, LPG3, LPG5 and LPG4 respectively. It was observed in this study that LPG-1 and LPG-2 fractions of lipopolysaccharide antigens induced maximum proliferation
of lymphocytes and also induces monocytes to produce significant amount of NO. These
fractionated LPS were found immunoreactive and will further be tested for the
development of immunodiagnostic kit, which will be useful to detect the presence of
anti-Brucella antibody in the infected host
