Evaluation of the antimeningococcal immunoglobin activity against five strains of Neisseria meningitidis group B from Latin America using mice as model.

To know the activity of antimeningococcal immunoglobulin, Balb/c mice of 18-22 g of body weight were challenged with 5 serotype B strains of Neisseria meningitidis (Nm) isolated from patients of different Latin American countries. The specific antimeningococcal Ig was extracted from the serum of volunteers previously vaccinated with the antimeningococcal BC vaccine VA-MENGOC-BC (Finlay Institute, Havana, Cuba). The Ig was intraperitoneally (IP) administered in a unique dose of 10 mg/mouse. The strains A, B, C, CH and D were inoculated IP in the following charges: strain A, 20 LD50; B, 25 LD50; C, 44.5 LD50; CH, 36 LD50, and D, 200, 20 and 2 LD50. For each strain, a control group received living bacteria and virulent stimulating factor (VSF). The Ig was injected 30 min before or 30 min after the challenge dose had been given, except for strain D, which only received the Ig 30 min after the challenge. As VSF, 0.5 mg of iron in the form of iron dextran was used. The experiment was analyzed considering the survival time after the challenge for each strain compared to the corresponding control group (C). When the Ig was used 30 min before the challenge, the protection period for the A strain was (C:18.1h) more than 72h (P<0.001) and 100% survival; for the B strain, (C:29.5h) 42h (P<0.05) and almost 20% survival; for the C strain (C:16.5h) 35h (P<0.01) with a 40% survival, and the CH strain (C:18.1h) 26.5h (P<0.02), with a 20% survival. When the Ig was injected 30 min after the challenge, the average survival time and the survival for the A strain was 28h (P<0.05) with 62.5%; for the B strain it was 42 h (P<0.005) and 0.0%; for the C strain 27.3 h (P<0.05) and 30%; for the CH strain 25.8h (P<0.05) and 0.0%, and for the D strain 19.1h, 26h, and more than 72h with a 0.0%, 60% and 100%, depending on the challenging dose. In general, the specific Ig used showed a protective effect in mice against the different Latin American strains tested. Additionally, the experimental model proved to be useful for the study of the antimeningococcal human Ig.