Publications by Year: 2016

Porcine reproductive and respiratory syndrome (PRRS) is a leading cause of economic burden to the pork industry worldwide. The routinely used modified live PRRS virus vaccine (PRRS-MLV) induces clinical protection, but it has safety concerns. Therefore, in an attempt to develop a safe and protective inactivated PRRSV vaccine, we generated PRRS-virus-like-particles (PRRS-VLPs) containing the viral surface proteins GP5-GP4-GP3-GP2a-M or GP5-M using a novel baculovirus expression system. Our in vitro results indicated that the desired PRRSV proteins were incorporated in both the VLPs preparations based on their reactivity in immunogold electron microscopy and ELISA. To boost their immunogenicity in pigs, we entrapped the PRRS-VLPs in PLGA nanoparticles and coadministered them intranasally with a potent adjuvant. We then evaluated their efficacy in pigs against a viral challenge using a virulent heterologous field isolate. Our results indicated that PRRS-VLPs induced an anamnestic immune response, since we observed boosted IgG and IFN-γ production in vaccinated and virus-challenged animals, but not during the pre-challenge period. Importantly, a two-log reduction in the lung viral load was detected in PRRS-VLP-vaccinated animals. In conclusion, we generated PRRS-VLPs containing up to five viral surface proteins and demonstrated their immunogenicity in pigs, but further studies are required to improve its immunogenicity and efficacy as a vaccine candidate.

Porcine reproductive and respiratory syndrome (PRRS) is caused by PRRS virus (PRRSV), which infects primarily the respiratory tract of pigs. Thus intranasal (IN) delivery of a potent vaccine-adjuvant formulation is promising. In this study, PRRS-MLV (VR2332) was coadministered ± an adjuvant Mycobacterium vaccae whole cell lysate or CpG ODN through intramuscular (IM) or IN route as a mist, and challenged with a heterologous PRRSV 1-4-4 IN at 42 days post-vaccination (dpv). At 14 and 26 dpv, vaccine viral RNA copies were one log greater in the plasma of PRRS-MLV IM compared to IN vaccinated pigs, and the infectious replicating vaccine virus was detected only in the IM group. In PRRS-MLV ± adjuvant IM vaccinated pigs, reduced viral RNA load and absence of the replicating challenged virus was observed at 7, 10 and 14 days post-challenge (dpc). At 14 dpc, in BAL fluid ≥ 5 log viral RNA copies were detected in all the pig groups, but the replicating challenged virus was undetectable only in IM groups. Immunologically, virus neutralizing antibody titers in the plasma of IM (but not IN) vaccine groups was ≥ 8 against the vaccine and challenged viruses. At 26 dpv, PRRS-MLV IM (without adjuvant) received pigs had significantly increased population of CD4 and CD8 T cells in PBMC. At 14 dpc, relatively increased population of IFN-γ(+) total lymphocytes, NK, CD4, CD8 and γδ T cells were observed in the MLV-IM group. In conclusion, PRRS-MLV IM vaccination induced the virus specific T cell response in pigs, but still it is required to improve its cross-protective efficacy.

Tuberculosis (TB) is a disease that kills one person every 18 s. TB remains a global threat due to the emergence of drug-resistant Mycobacterium tuberculosis (M.tb) strains and the lack of an efficient vaccine. The ability of M.tb to persist in latency, evade recognition following seroconversion, and establish resistance in vulnerable populations warrants closer examination. Past and current research has primarily focused on examination of the role of alveolar macrophages and dendritic cells during M.tb infection, which are critical in the establishment of the host response during infection. However, emerging evidence indicates that the alveolar epithelium is a harbor for M.tb and critical during progression to active disease. Here we evaluate the relatively unexplored role of the alveolar epithelium as a reservoir and also its capacity to secrete soluble mediators upon M.tb exposure, which influence the extent of infection. We further discuss how the M.tb-alveolar epithelium interaction instigates cell-to-cell crosstalk that regulates the immune balance between a proinflammatory and an immunoregulatory state, thereby prohibiting or allowing the establishment of infection. We propose that consideration of alveolar epithelia provides a more comprehensive understanding of the lung environment in vivo in the context of host defense against M.tb.

Campylobacter jejuni (C. jejuni), a Gram-negative microaerophilic bacterium, is a predominant cause of bacterial foodborne gastroenteritis in humans worldwide. Despite its importance as a major foodborne pathogen, our understanding of the molecular mechanisms underlying C. jejuni stress survival and pathogenesis is limited. Inorganic polyphosphate (poly P) has been shown to play significant roles in bacterial resistance to stress and virulence in many pathogenic bacteria. C. jejuni contains the complete repertoire of enzymes required for poly P metabolism. Recent work in our laboratory and others have demonstrated that poly P controls a plethora of C. jejuni properties that impact its ability to survive in the environment as well as to colonize/infect mammalian hosts. This review article summarizes the current literature on the role of poly P in C. jejuni stress survival and virulence and discusses on how poly P-related enzymes can be exploited for therapeutic/prevention purposes. Additionally, the review article identifies potential areas for future investigation that would enhance our understanding of the role of poly P in C. jejuni and other bacteria, which ultimately would facilitate design of effective therapeutic/preventive strategies to reduce not only the burden of C. jejuni-caused foodborne infections but also of other bacterial infections in humans.

Pigs are believed to be one of the important sources of emerging human and swine influenza viruses (SwIV). Influenza virus conserved peptides have the potential to elicit cross-protective immune response, but without the help of potent adjuvant and delivery system they are poorly immunogenic. Biodegradable polylactic-co-glycolic acid (PLGA) nanoparticle (PLGA-NP) based vaccine delivery system enhances cross-presentation of antigens by the professional antigen presenting cells. In this study, Norovirus P particle containing SwIV M2e (extracellular domain of the matrix protein 2) chimera and highly conserved two each of H1N1 peptides of pandemic 2009 and classical human influenza viruses were entrapped in PLGA-NPs. Influenza antibody-free pigs were vaccinated with PLGA-NPs peptides cocktail vaccine twice with or without an adjuvant, Mycobacterium vaccae whole cell lysate, intranasally as mist. Vaccinated pigs were challenged with a virulent heterologous zoonotic SwIV H1N1, and one week later euthanized and the lung samples were analyzed for the specific immune response and viral load. Clinically, pigs vaccinated with PLGA-NP peptides vaccine had no fever and flu symptoms, and the replicating challenged SwIV was undetectable in the bronchoalveolar lavage fluid. Immunologically, PLGA-NP peptides vaccination (without adjuvant) significantly increased the frequency of antigen-specific IFNγ secreting CD4 and CD8 T cells response in the lung lymphocytes, despite not boosting the antibody response both at pre- and post-challenge. In summary, our data indicated that nanoparticle-mediated delivery of conserved H1N1 influenza peptides induced the virus specific T cell response in the lungs and reduced the challenged heterologous virus load in the airways of pigs.