Detection of free and immune-complexed serine protease and its antibody in TB patients with and without HIV co-infection.
OBJECTIVE
To understand the usefulness of detecting tuberculous IgG antibodies against mycobacterial excretory-secretory 31 kDa serine protease antigen (SEVA TB ES-31) and circulating free and circulating immune-complexed (CIC) serine protease in TB patients with and without HIV infection.


METHODS
Serum was collected from 144 individuals: patients with TB, with TB-HIV co-infection and HIV infection only, and ill and healthy controls. SEVA TB ES-31 antigen, a serine protease isolated from Mycobacterium tuberculosis H37Ra culture fluid, was used in indirect penicillinase ELISA to detect tuberculous antibodies. Similarly, affinity purified anti-ES-31 antibody was used in sandwich ELISA to detect circulating free and CIC serine protease.


RESULTS
There was less sensitivity for tuberculous antibody in HIV-infected TB patients (46%) than in those with TB alone (87%) using mycobacterial serine protease. However, the sensitivity of detection of TB in the presence of HIV increased to 87% by concomitant detection of circulating free and CIC serine protease antigen.


CONCLUSIONS
Detection of free and CIC tuberculous serine protease antigen along with antibody is more useful for detecting TB in the presence of HIV co-infection.
Shende
N
N
Jamnalal Bajaj Tropical Disease Research Centre, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha, Maharashtra, India.
Gupta
S
S
Bhatia
A S
AS
Kumar
S
S
Harinath
B C
BC
D000917:Antibody Formation; D000936:Antigen-Antibody Complex / Q000032:analysis*; D000942:Antigens, Bacterial / Q000276:immunology; D015897:Comorbidity; D004797:Enzyme-Linked Immunosorbent Assay; D015658:HIV Infections / Q000150:complications* / Q000382:microbiology; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D012697:Serine Endopeptidases / Q000276:immunology*; D014397:Tuberculosis, Pulmonary / Q000276:immunology* / Q000821:virology*
D000936:Antigen-Antibody Complex; D000942:Antigens, Bacterial; D007074:Immunoglobulin G; D012697:Serine Endopeptidases