Open AccessIgM but not IgG monoclonal anti‐ Nocardia brasiliensis antibodies confer protection against experimental actinomycetoma in BALB/c mice
Author(s) -
GonzalezSuarez Maria L.,
SalinasCarmona Mario C.,
PérezRivera Isabel
Publication year - 2009
Publication title -
fems immunology & medical microbiology
Language(s) - English
Resource type - Journals
eISSN - 1574-695X
pISSN - 0928-8244
DOI - 10.1111/j.1574-695x.2009.00575.x
Subject(s) - biology , nocardia brasiliensis , microbiology and biotechnology , monoclonal antibody , antibody , antigen , in vivo , immune system , immunoglobulin m , immunoglobulin g , nocardia , virology , immunology , bacteria , nocardiosis , genetics
Nocardia brasiliensis is a facultative intracellular microorganism that produces a human chronic infection known as actinomycetoma. Human and mouse anti‐ N. brasiliensis antibody response identify P24, P26 and P61 immunodominant antigens. In this work, we generated immunoglobulin M (IgM) and IgG monoclonal antibodies (mAbs) specific to immunodominant P61 antigen. The monoclonal IgM (NbM1) and IgG2a (NbG1) antibodies were assessed for their in vitro bactericidal activity, in vivo protective effect and ability to block catalase activity. These mAbs specifically recognized P61, but they did not inhibit its enzyme activity. The in vitro bactericidal effect of NbG1 was higher than the killing ability of the IgM mAb. In vivo experiments with a murine model of experimental infection with N. brasiliensis injected into rear footpads was used to test the effect of NbM1 and NbG1. The negative untreated group developed a chronic actinomycetoma within 4 weeks. IgM mAbs conferred protection to BALB/c mice infected with N. brasiliensis . IgG mAb lacked this protective effect. IgM mAb showed a dose–response correlation between antibody concentration and lesion size. These results demonstrate that humoral immune response mediated by antigen‐specific IgM antibody protects against an intracellular bacterial infection.