Lactococcus lactis as an adjuvant and delivery vehicle of antigens against pneumococcal respiratory infections

Most studies of Lactococcus lactis as delivery vehicles of pneumococcal antigens are focused on the effectiveness of mucosal recombinant vaccines against Streptococcus pneumoniae in animal models. At present, there are three types of pneumococcal vaccines: capsular polysaccharide pneumococcal vaccines (PPV), protein-polysaccharide conjugate pneumococcal vaccines (PCV) and protein-based pneumococcal vaccines (PBPV). Only PPV and PCV have been licensed. These vaccines, however, do not represent a definitive solution. Novel, safe and inexpensive vaccines are necessary, especially in developing countries. Probiotic microorganisms such as lactic acid bacteria (LAB) are an interesting alternative for their use as vehicles in pneumococcal vaccines due to their GRAS (Generally Recognized As Safe) status. Thus, the adjuvanticity of Lactococcus lactis by itself represents added value over the use of other bacteria, a question dealt with in this review. In addition, the expression of different pneumococcal antigens as well as the use of oral and nasal mucosal routes of administration of lactococcal vaccines is considered. The advantages of nasal live vaccines are evident; nonetheless, oral vaccines can be a good alternative when the adequate dose is used. Another point addressed here is the use of live versus inactivated vaccines. In this sense, few researchers have focused on inactivated strains to be used as vaccines against pneumoccoccus. The immunogenicity of live vaccines is better than the one afforded by inactivated ones; however, the probiotic-inactivated vaccine combination has improved this matter considerably. The progress made so far in the protective immune response induced by recombinant vaccines, the successful trials in animal models and the safety considerations of their application in humans suggest that the use of recombinant vaccines represents a good short-term option in the control of pneumococcal diseases

Field evaluation of the effect of a probiotic-containing Bacillus licheniformis and Bacillus subtilis spores on the health status, performance, and carcass quality of grower and finisher pigs

The aim of the study was to assess the efficacy of BioPlus 2B, a probiotic containing Bacillus licheniformis and B. subtilis spores, on the health status and productivity of pigs, during weaning, growing and finishing stages of growth. On a commercial farrow-to-finish farm, five experimental groups were formed, each of 54 weaned piglets. The pigs of the first group (double controls) received normal feed with no probiotic and the pigs of the second group (untreated controls) received BioPlus 2B only during the weaning stage. The pigs of the third, the fourth and the fifth group received the same as the second group feed but, at the growing and at a part of the finishing stages, supplemented with three different doses of Bioplus 2B, a low, medium and high dose, respectively. The results have shown that, compared with the double controls, BioPlus 2B-treated pigs had a lower morbidity and mortality during the whole trial period, compared with the double controls (range from 9.26 to 14.81% versus 25.93% and from 0.00 to 3.70% versus 11.1%, respectively), as a result of the lower incidence of post-weaning diarrhoea due mainly to Escherichia coli. Weight gain, feed conversion ratio and carcass quality of the BioPlus 2B-treated pigs were significantly improved compared with the double controls, whilst the beneficial effects of the probiotic were more pronounced when the medium and high doses were used. © 2004 Blackwell Verlag