Induction of Immune Responses in Mice after Intragastric Administration of Lactobacillus casei Producing Porcine Parvovirus VP2 Protein

Abstract

Lactobacillus casei ATCC 393 was selected as an antigen delivery vehicle for mucosal immunization against porcine parvovirus (PPV) infection. A 64-kDa fragment of PPV major protective antigen VP2 protein was used as the parvovirus antigen model. A recombinant Lactobacillus expressing VP2 protein was constructed with plasmid pPG611.1, where expression and localization of the VP2 protein from recombinant Lc393-rPPV-VP2 was detected via sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blotting, and immunofluorescence. Both local mucosal and systemic immune responses against PPV were induced in BALB/c mice immunized orally with the recombinant Lactobacillus expressing VP2 protein. The induced antibodies demonstrated neutralizing effects on PPV infection. These data indicated that the use of recombinant lactobacilli could be a valuable strategy for future vaccine development of PPV.Porcine parvovirus (PPV), 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 (3,12,13,22), and the virus causes serious losses for pig producers. The molecular features of PPV are similar to those of other autonomous parvoviruses. PPV is a small, nonenveloped virus, and the virion contains a 5-kb, linear, minus-polarity, single-stranded DNA genome (25), which is encapsidated within a simple icosahedron protein coat composed of three structural polypeptides (VP1, VP2, and VP3, with masses of 84, 64, and 60 kDa, respectively) (24). The VP2 protein encompasses major antigenic domains of PPV and could induce PPV-neutralizing antibodies for the neutralization of PPV infection (26,32,38). Therefore, the VP2 protein plays a major role in PPV diagnosis and immune prophylaxis.The mucosa tissues are particularly important for protection against diseases, such as those caused by viral, bacterial, and parasitic pathogens which invade the mucosal system (18, 39). Vaccines administered by parenteral routes generally fail to stimulate mucosal immune responses. Mucosal immunization has proven to be an effective approach against the colonization of pathogens and their further spread to the systemic circulation (7,20,23). Therefore, it is necessary to develop efficient and safe antigen vectors that will be able to trigger mucosal and systemic immune responses. One promising approach relies on the use of live bacterial vehicles (21). The potentiality of recombinant lactic acid bacteria to deliver heterologous antigens to the mucosal immune system has been investigated during the last decade (10,11,19,28,30,31,37). This approach offers a number of advantages (such as noninvasiveness and the possibility of eliciting both mucosal and systemic immune responses) over the traditional parenteral vaccination. In addition, lactobacilli have been used in a large variety of industrial food fermentation and preservation processes, are known for their beneficial effects on the health of humans and animals, ...

Oral Immunization with RecombinantLactobacillus plantarumInduces a Protective Immune Response in Mice with Lyme Disease

“…However, public fear of using an attenuated pathogen as a vaccine carrier has deterred its acceptance. Recent studies have shown that oral administration of a number of lactobacilli expressing recombinant immunogens induces local mucosal (42) and systemic antibody responses (62). Other studies have explored this further and showed that immune responses induced via lactobacilli delivered through oral vaccination confer some protection against challenge with the respective pathogen (27,31,32,60).…”

Mucosal and Systemic Immune Responses Induced by Recombinant Lactobacillus spp. Expressing the Hemagglutinin of the Avian Influenza Virus H5N1

“…Thus, HA 1 is an important target for vaccine development. Lactobacillus is widely used as a live vaccine vehicle against various microbes (1,7,35). Accordingly, we constructed a recombinant plasmid, pLEM415-PHA 1 , and recombinant lactobacillus strains, LA4356-pH and DLD17-pH, that produce the HPAI virus protective antigen HA 1 .…”

Generation of recombinant porcine parvovirus virus-like particles in Saccharomyces cerevisiae and development of virus-specific monoclonal antibodies

“…To meet the need for stable recombinant VLPs of PPV, several expression systems were tested as an alternative to baculovirus expression system that is a major source of the antigen for the market [26]. E. coli [23], Lactobacillus casei [21], and recently yeast Pichia pastoris [27] were reported to have been successfully used for producing PPV VP2 protein, but VLP formation in these expression systems has not been confirmed. To our knowledge, our study provides the first evidence of stable recombinant PPV VP2 VLPs not produced in baculovirus expression system.…”

“…These loops are shown to possess many B-cell epitopes and can tolerate insertions [19,20] that make PPV VP2 a potential antigen carrier and play a key role in PPV diagnosis and immune prophylaxis [21]. The structure of PPV capsid composed of baculovirus system generated recombinant VP2 is available in 3.5Å resolution (PDB Accession Number 1K3V) [22].…”

“…Immunogenic major capsid protein VP2 of PPV has been synthesized in several expression systems including bacteria [21,23]. PPV VP2 protein expressed using the baculovirus expression vector system was shown to assemble into viruslike particles (VLPs) similar in size and morphology to the original virions.…”