== Inhibition of viral plaque formation by sera (a) and intestinal lavage fluids (b) prepared from pigs orally immunized with Lc393-rE290-VP2. the familyFlaviviridae, is usually a small, enveloped, single-stranded RNA computer virus. Under natural conditions, the pig is the only susceptible species, and the computer virus can cause acute, subacute, or chronic disease (10,26,29). Porcine parvovirus (PPV), GW842166X characterized as a member of the autonomous parvoviruses, is a major cause of reproductive failure in swine, resulting in early embryonic death, fetal death, stillbirths, and delayed return to estrus (5,24,28). Enormous economic losses to pig industries have been caused by these two pathogens. Therefore, the development of an efficient vaccine against CSFV and PPV simultaneously is usually of practical significance. For vaccines against CSFV, the important role of humoral immune responses has been investigated, particularly in terms of neutralizing antibodies. For instance, pigs that were immunized with recombinant computer virus expressing CSFV E0 or E2 protein were guarded against CSFV challenge (47). In some cases, immunization of animals with recombinant computer virus expressing other CSFV proteins failed to induce detectable neutralizing antibodies, whereas the animals were guarded against lethal CSFV contamination, which indicated that virus-specific T lymphocytes participated in a protective immune response against CSFV (38,44,48). Currently, cellular immune responses, especially production of virus-specific cytotoxic T lymphocytes (CTL), are receiving more attention for their potential functions in developing efficient epitope vaccines against CSFV (18,35). Several CSFV-specific T-cell epitopes have been identified (3,8,32). Of them, the epitope peptide 290 (KHKVRNEVMVHWFDD), located at amino acid residues 1446 to 1460 of the CSFV nonstructural protein NS2-3, could be advantageous, as it harbors a CSFV-specific helper T-cell epitope and a CTL epitope, which could elicit both CD4+and CD8+T-cell responses (3). Therefore, peptide 290 is a promising candidate for an epitope vaccine for the control of CSF. Among vaccines against PPV, the inactivated vaccine is the one most often used to prevent and control contamination, and humoral immune responses, in particular, neutralizing antibodies, play an important role. Therefore, the development of efficient vaccines that induce antibodies which neutralize PPV contamination is desirable. The VP2 protein of PPV encompasses major antigenic domains and is therefore regarded as a promising candidate immunogen with the capacity to induce neutralizing antibodies (27,41). Moreover, CSFV and PPV initiate their infectious cycle at the mucosal surfaces. Although parenteral vaccination is usually efficient in eliciting a protective immune response, the parenteral routes generally fail to stimulate mucosal immune responses and cannot efficiently prevent the pathogens from entering the body via the mucosae. Therefore, efficient protection against mucosal invasion requires the development of new vaccines to induce protective mucosal immune responses at the contamination point (17,21). In this respect, mucosal immunization has been proven to be an effective approach GW842166X (9,22). Thus, it is necessary to develop efficient and safe antigen vectors that could trigger mucosal and systemic immune responses. One promising approach Thy1 relies on the use of live vehicles (2).Lactobacillusstrains possess many properties that make them attractive candidates as antigens carriers for the presentation to the mucosae of compounds with pharmaceutical interest, in particular, immunomodulators and vaccines. Lactobacilli are well known for having beneficial effects on the health of humans and animals. In addition, lactobacilli can survive in and colonize the intestinal tract (1,50) and, furthermore, induce a nonspecific immunoadjuvant effect (30). The potential of live recombinantLactobacillusto deliver heterologous antigens to the immune system has been investigated (14,31,33,34,36,40,51), suggesting the feasibility of using lactobacilli as safe oral vaccines. In the present study, a recombinantLactobacillusstrain coproducing a CSFV-specific CTL epitope and PPV VP2 protein was developed using the plasmid pPG612.1 as an expression vector, and its immunogenicity as an oral vaccine used to elicit antiviral mucosal and systemic immune responses in pigs was analyzed. Our data showed that oral immunization with the recombinant strain was able to induce CSFV-specific CTL responses against CSFV challenge and neutralizing antibodies against PPV contamination in pigs, which indicate a new strategy for the development of CSFV and PPV vaccines. == MATERIALS AND METHODS GW842166X == == Bacteria, plasmids, and viruses. == Lactobacillus caseiATCC 393 and plasmid pPG612.1 were kindly gifted by J. Seegers (NIZO, Netherlands). CSFV strain Shimen and PPV NADL-2 strain were kindly supplied by the China Institute of Veterinary Drug Control. PPV strain LJL12 was preserved in the Veterinary Department, Northeast Agricultural University, Harbin, People’s Republic of China. == Construction of the recombinantLactobacillusstrain. == All DNA manipulations were performed according to standard procedures (39). The genomic DNA of PPV strain LJL12.