PREVENTIVE ADMINISTRATION OF LACTIC ACID BACTERIA IN Streptococcus pneumoniae INFECTION MODEL. POTENTIAL USE AS VACCINE VECTORS

VILLENA JULIO; MEDINA MARCELA; ALVAREZ SUSANA

Tafí del Valle. Tucumán

Jornada; XXII Jornadas Científicas de la Asociación de Biología de Tucumán; 2005

Asociación de Biología de Tucumán

We studied the adjuvant effect of Lactococcus lactis NZ9000 (Ll) and Lactobacillus plantarum 37A (Lp), orally administered, in a Streptococcus pneumoniae (Sp) respiratory infection. Swiss-albine adult mice were treated with Ll or Lp (107, 108 or 109 UFC/day) for 2, 5 and 7 days (d). At the end of each treatment mice were infected intranasally with Sp (106 UFC per mouse) and during 15 d post-infection we performed: A)Bacterial cells counts in lung  and blood samples, B)Hematocrit and haemoglobin, C)Total and differential leucocytes counts in blood and bronco-alveolar lavages (BAL). Results: Only Ll administered for 5d in a dose of 108 (Ll5d8) was able to reduce significantly the pathogen counts in lung and blood samples. The number of leucocytes and neutrophils in blood and BAL increased significantly in all groups after the challenge, but mice treated with Ll5d8 showed higher levels than the controls. Lp failed to improve resistance against Sp. Conclusion: The oral administration of Ll in the appropriate dose, improves the resistance against Sp, by inducing a stronger recruitment of inflammatory cells. This immunoadjuvant effect and their ability to be easily transformed made Ll a good candidate as delivery system for mucosal vaccination.