Lectins and their role in a new polyvalent bacterial vaccine against ARI.

The potency of the polyvalent bacterial vaccine (Infectvac) to prevent lethal infections with S. pneumoniae ATCC 6301 was examined. NMRI-mice were protected 2-5 times better than untreated controls. The protection is based on activation of resistance-mechanisms, e.g. interferon production. Most interesting is a strong activation of the phagocytosis-killing-system of alveolar macrophages after oral application of antigen (information: gut mucosa to lung mucosa). Using the same infection model the important role of bacterial lectins for infectious diseases was demonstrated. Blocking the combining site of the bacterial lectin of S. pneumoniae by intranasal application of N-acetylglucosamine (the specific carbohydrate for the lectin) was able to prevent a lethal infection with S. pneumoniae 3-times better than PBS or using not lectin relevant carbohydrates. Therefore, blocking the lectin receptor with specific carbohydrates might also be of clinical relevance to prevent acute respiratory infections (ARI).