Antibodies prevalence against Haemophilus influenzae type b in Jeddah population, Saudi Arabia. III. Antibodies avidity

Serum From Melioidosis Survivors Diminished Intracellular Burkholderia pseudomallei Growth in Macrophages: A Brief Research Report

Melioidosis is a neglected tropical disease with high mortality rate. It is caused by the Gram-negative, CDC category B select agent Burkholderia pseudomallei (B. ps) that is intrinsically resistant to first-line antibiotics. An antibody-based vaccine is likely to be the most effective control measure. Previous studies have demonstrated significant mechanistic roles of antibodies in protection against death in animal models, but data from human melioidosis is scarce. Herein, we used in-vitro antibody-dependent cellular phagocytosis and growth inhibition assays to assess the mechanism of protective antibodies in patients with acute melioidosis. We found that serum from patients who survived the disease enable more live B. ps to be engulfed by THP-1 derived macrophages (median 1.7 × 10³ CFU/ml, IQR 1.1 × 10³-2.5 × 10³ CFU/ml) than serum from patients who did not survive (median 1.2 × 10³ CFU/ml, IQR 0.7 × 10³-1.8 × 10³, p = 0.02). In addition, the intracellular growth rate of B. ps pre-opsonized with serum from survivors (median 7.89, IQR 5.58–10.85) was diminished when compared with those with serum from non-survivors (median 10.88, IQR 5.42–14.88, p = 0.04). However, the difference of intracellular bacterial growth rate failed to reach statistical significance when using purified IgG antibodies (p = 0.09). These results provide new insights into a mechanistic role of serum in protection against death in human melioidosis for antibody-based vaccine development.

Circulating innate and adaptive immunity against anti-Haemophilus influenzae type b

Haemophilus influenzae type b (Hib) are one of most dangerous microbes that occupies the paediatric nasopharyngeal as a commensal opportunistic bacterium, which may lead to meningitis in uncontrolled infection. Colonisation of pharyngeal tissues is the starting point for most H. influenzae infections, which may develop into invasive diseases, such meningitis. The vaccination against Hib in specific, as well as against most of vaccines preventable diseases; in general, play a major role in reducing children (< 5 years old) Hib meningitis from 57/100,000 to the lowest known Hib meningitis incidents in the history. First invented Hib vaccine was licensed in 1985 and contained Hib capsular polysaccharide (CPS); afterward, conjugate vaccines have been innovated and licensed on the road to improve Hib vaccine efficacy. Polyribosylribitol phosphate (PRP) is the main vaccine unite structure. Since anti-CPS antibodies in the serum reflect the extent of the acquired immunity against Hib infections, the concentration of ⩾ 0.15 g/ml of anti-CPS is believed to be an indicator for short-term protection from invasive Hib diseases, whereas one-month post-completion of primary Hib immunization concentration of ⩾ 1.0 g/ml is trusted to be immunological protective. As considered that serum anti-CPS antibodies are effectively linked to protection, the evaluation of antibodies concentration and reconsideration of published worldwide populations antibodies concentration are consider vital strides on the way to accurate valuation of Hib immunity that induced by vaccination; either direct or herd. As documented, some populations; worldwide, still susceptible to invasive Hib infections. Several populations worldwide remain vulnerable to Hib-related infections. We believe that up-to-date review article regarding circulated Hib immunology, represented in anti-Hib antibodies and worldwide Hib incidences will provide a precious information for microbiologists, public health officials, epidemiologists, immunologists, and strategic preventive healthcare executives.