Riccardo Villa

Comparative evaluation of PRRS virus infection in vaccinated and naïve pigs.

The purpose of this study was to evaluate the time-course of the immune response to a field Porcine Respiratory and Reproductive Syndrome virus (PRRSV) strain in PRRS-naïve, untreated pigs, as well as in four groups of age and breed-matched pigs injected with a live attenuated PRRS vaccine, its adjuvant, an inactivated PRRS vaccine and an irrelevant, inactivated Porcine Circovirus type 2 (PCV2) vaccine, respectively. PRRSV infection was confirmed in all groups by PCR and antibody assays. The antibody response measured by ELISA took place earlier in pigs injected with the live attenuated vaccine, which also developed a much stronger serum-neutralizing antibody response to the vaccine strain. Yet, no clear protection was evidenced in terms of viremia against the field virus strain, which showed 11.1% nucleotide divergence in ORF7 from the vaccine strain. In vitro, the interferon (IFN)-γ response to PRRSV was almost absent on PVD 60 in all groups under study, whereas the prevalence of interleukin (IL)-10 responses to PRRSV was fairly high in PCV2-vaccinated animals, only. Results indicate that distinct patterns of immune response to a field PRRSV strain can be recognized in PRRS-vaccinated and naïve pigs, which probably underlies fundamental differences in the development and differentiation of PRRSV-specific immune effector cells.

IPEC-J2 Cells as Reporter System of the Anti-Inflammatory Control Actions of Interferon-Alpha

Interferon-alpha (IFN-α) shows potent immunomodulatory properties, which underlies its use for low-dose oral treatments of diverse viral infections and immunopathological conditions. The studies on oral administration have been hampered by the lack of recognized in vitro models, reproducing the in vivo control action of IFN-α over inflammatory cytokine responses. Owing to these reasons, the aim of our study was to validate IPEC-J2 (a continuous cell line of porcine intestinal epithelial cells) as a reporter system of the properties of IFN-α. Three different experimental conditions (oxidative stress, inflammatory response, and amplification of lymphoid cell signals) were selected to evaluate the effects of porcine recombinant IFN-α1 (rIFN-α) and 2 natural porcine IFN-α preparations (nIFN-α). The IFNs under study showed significantly different control actions in IPEC-J2 cells. In particular, rIFN-α was shown to down-regulate interleukin (IL)-8, IL-1β, tumor necrosis factor (TNF)-α, and β-defensin 1 genes either directly, or indirectly through second messengers released by IFN-α-treated lymphoid cells. With regard to IL-6, only second messengers from IFN-α-treated lymphoid cells could regulate the expression of this cytokine. Our results suggest that IPEC-J2 cells can be a useful tool for investigating the regulatory actions of type I IFNs and the second messengers thereof. The results provided by this model could be conveniently exploited in studies on enteric diseases sustained by infectious or noninfectious stressors.

Characterization of the interferon-α response of pigs to the weaning stress.

The interferon (IFN)-α response of pigs to the stressing event of early weaning was investigated in a field trial. All the animals under study remained healthy and tested negative for common viral infections. However, a low-titered IFN-α response was detected in many sera by a bioassay on Madin-Darby bovine kidney (MDBK) cells on day +6 after weaning. Porcine IFN-α was unambiguously identified by a neutralization assay on a pool of IFN-α-positive sera. By gel filtration chromatography, the antiviral activity of sera on MDBK cells could be traced back to 3 components of apparent molecular mass 27/18/<14 kDa. Additional components of apparent molecular mass 58 and 41 kDa were revealed by ELISA in Nonidet P-40 lysates of peripheral blood mononuclear cells (PBMC). Also, many pigs tested positive in flow cytometry assays on PBMC for intracellular IFN-α. The expression of porcine IFN-α genes was investigated by reverse transcriptase (RT) real-time polymerase chain reaction at days -1, +6, and +12 with regard to weaning in PBMC of 9 piglets. On days -1 and +12, IFN A5, A6, A12, as well as (in fewer pigs) A1, A7, A11, and A2 genes were shown to be expressed. On the contrary, none of the above genes was expressed on day +6, when plenty of pig sera were IFN-α-positive. Our results indicate that weaning causes the release of IFN-α and the transient shut-off of the corresponding gene transcriptions in PBMC. Interestingly, only IFN A9 gene transcription was shown in vitro to be virus induction-dependent.

An alternative method to isoenzyme profile for cell line identification and interspecies cross-contaminations: cytochrome b PCR-RLFP analysis

One of the major risks in cell culture laboratories is the misidentification and cross-contamination of cell lines. Several methods have been used to authenticate cell lines, including isoenzyme profiling, the test suggested by European Farmacopeia, which is performed at the Tissue Culture Centre in Brescia. However, this method displays several disadvantages, such as high variability and low reproducibility, and it is time consuming and requires high cell concentrations to be performed. Therefore, an alternative method has been developed to confirm the specie of origin of 27 different animal cell cultures. A polymerase chain reaction (PCR)–restriction fragment length polymorphism (RFLP) assay was optimized, based on the use of a pair of primers that anneal to a portion of the cytochrome b gene in all the species. The amplification product was digested with a panel of six restriction enzymes, and the pattern derived was resolved on 3% high-resolution agarose gel. For 23 species, this protocol produced a unique restriction pattern, and the origin of these animal cells resulted to be confirmed by this analysis. Furthermore, results indicate that cytochrome b PCR-RFLP was able to amplify target sequences using very low amounts of deoxyribonucleic acid (DNA). Its sensitivity in detecting interspecies, cross-contamination was comparable to that of isoenzyme analysis (contaminating DNA should represent at least 10% of the total DNA). For 4 of the 27 species (sheep, dog, Guinea pig, and Rhesus monkey) the observed pattern, even if highly reproducible, showed additional bands; for these species, specific PCR was also performed.

Isolation and culture of pig tonsil lymphocytes.

Tonsils are secondary lymphoid organs that play an important role in host defense. The aim of our study was to develop reliable procedures for isolation and culture of pig tonsil cells, and to validate their possible use in functional immunoassays. Using our isolation procedure, we recovered on average 238.7 ± 107.1 × 10(6) cells per tonsil couple with a mean vitality of 89.8 ± 2.7%. These values significantly decreased 8 months after freezing at -80°C along with the subsequent spontaneous release of both IgA and IgG in culture. These results suggest to use pig tonsil cells within 2 months from thawing to maintain suitable conditions in terms of recovery, vitality and release of antibody in vitro. Tonsil mononuclear cells also showed the ability to secrete antimicrobial peptides and to respond in vitro to immunological stimuli. On the whole, our study has defined operating conditions for tonsil processing, control of bacterial contaminations, time limits of storage at -80°C, as well as for evaluating polyclonal Ig production in vitro. Such procedures are likely to be of some importance in studies on regional immunity and in the development of large animal models for biomedical sciences.

Evaluation of safety and efficacy of DNA vaccines against bovine herpesvirus-1 (BoHV-1) in calves

Four DNA vaccines against BoHV-1 were evaluated for their efficacy in calves. Twelve animals were divided into four groups which were injected with four different DNA vaccines: pVAX-tgD (Vaccine A); pVAX-tgD co-immunised with pVAX-48CpG (Vaccine B); pVAX-UbiLacI-tgD-L (Vaccine C); pVAX-UbiLacI-tgD-L co-immunised with pVAX-48CpG (Vaccine D). Three additional calves were given the plasmid vector and served as controls. Ninety days after the first vaccination all calves were challenge infected with BoHV-1. All animals developed a severe form of infections bovine rhinotracheitis. Only the calves given the pVAX-tgD co-immunised with pVAX-48CpG (Vaccine B) developed humoral antibodies against BoHV-1 between 56 and 90 days after the first vaccination, whereas in calves of other groups and in the controls, antibodies appeared only after the infection. In the calves vaccinated with either pVAX-tgD (Vaccine A) or pVAX-tgD combined with pVAX-48CpG (Vaccine B), BoHV-1-specific IFN-γ secreting cells were detected in PBMCs 90 days after the first vaccination and their number increased after challenge exposure. In the other groups the IFN-γ secreting cells were detected after virus infection and at low values.

Transformation and Tumorigenicity Testing of Simian Cell Lines and Evaluation of Poliovirus Replication

The key role of cell cultures in different scientific fields is worldwide recognized, both as in vitro research models alternative to laboratory animals and substrates for biological production. However, many safety concerns rise from the use of animal/human cell lines that may be tumorigenic, leading to potential adverse contaminations in cell-derived biologicals. In order to evaluate the suitability of 13 different cell lines for Poliovirus vaccine production, safety and quality, in vitro/in vivo tumorigenicity and Poliovirus propagation properties were evaluated. Our results revealed that non-human primate cell lines CYNOM-K1, FRhK-4, 4MBr-5 and 4647 are free of tumorigenic features and represent highly susceptible substrates for attenuated Sabin Poliovirus strains. In particular, FRhK-4 and 4647 cell lines are characterized by a higher in vitro replication, resulting indicated for the use in large-scale production field.

Evaluation of Different DNA Vaccines against Porcine Reproductive and Respiratory Syndrome (PRRS) in Pigs

In veterinary medicine, there have been different experiences with the plasmid DNA vaccination. In this area and with the hypothesis to demonstrate the effectiveness of different plasmids encoding porcine respiratory and reproductive syndrome (PRRS), five DNA vaccines against PRRS were evaluated for their innocuity and efficacy in pigs. Eighteen animals were divided into five groups which were injected with five (A, B, C, D, E) different DNA vaccines. Albeit, none of the proposed vaccines were able to protect the animals against PRRS virus. Only vaccines A and B were able to reduce the clinical signs of the infection. ELISA IgM were detected 30 days after the first vaccination in the pigs injected by Vaccine A or B. ELISA IgG were detected 90 days after the first vaccination in the pigs injected by Vaccine B or C. Neutralizing antibody were detected Post Challenge Days 61 (PCD) in all groups. In the pigs inoculated with Vaccine C, IFN-γ were detected 90 days after first vaccination, and after challenge exposure they increased. In the other groups, the IFN-γ were detected after challenge infection. Pigs injected with each of the vaccines A, B, C, D and E showed a significantly higher level of CD4−CD8+ lymphocytes (p < 0.001) after infection in comparison with their controls.

Potential neoplastic evolution of Vero cells: in vivo and in vitro characterization

Vero cell lines are extensively employed in viral vaccine manufacturing. Similarly to all established cells, mutations can occur during Vero cells in vitro amplification which can result in adverse features compromising their biological safety. To evaluate the potential neoplastic evolution of these cells, in vitro transformation test, gene expression analysis and karyotyping were compared among low- (127 and 139 passages) and high-passage (passage 194) cell lines, as well as transformed colonies (TCs). In vivo tumorigenicity was also tested to confirm preliminary in vitro data obtained for low passage lines and TCs. Moreover, Vero cells cultivated in foetal bovine serum-free medium and derived from TCs were analysed to investigate the influence of cultivation methods on tumorigenic evolution. Low-passage Vero developed TCs in soft agar, without showing any tumorigenic evolution when inoculated in the animal model. Karyotyping showed a hypo-diploid modal chromosome number and rearrangements with no difference among Vero cell line passages and TCs. These abnormalities were reported also in serum-free cultivated Vero. Gene expression revealed that high-passage Vero cells had several under-expressed and a few over-expressed genes compared to low-passage ones. Gene ontology revealed no significant enrichment of pathways related to oncogenic risk. These findings suggest that in vitro high passage, and not culture conditions, induces Vero transformation correlated to karyotype and gene expression alterations. These data, together with previous investigations reporting tumour induction in high-passage Vero cells, suggest the use of low-passage Vero cells or cell lines other than Vero to increase the safety of vaccine manufacturing.

Veterinary Biobank Facility: Development and Management for Diagnostic and Research Purposes

Biobanking is an essential tool for ensuring easy availability of high-quality biomaterial collections that combine essential samples and epidemiological, clinical, and research data for the scientific community. Specimen collection is an integral part of clinical research. Indeed, every year throughout the world, millions of biological samples are stored for diagnostics and research, but in many fields the lack of biological material and models is a major hindrance for ongoing research. A biobank facility provides suitable samples for large-scale screening studies and database repositories. Software dedicated to biological banks simplify sample registration and identification, the cataloging of sample properties (type of sample/specimen, associated diseases and/or therapeutic protocols, environmental information, etc.), sample tracking, quality assurance, and specimen availability characterized by well-defined features. Biobank facilities must adopt good laboratory practices (GLPs) and a stringent quality control system and also comply with ethical issues, when required. The creation of a veterinary network can be useful under different aspects: the first one is related to the importance of animal sciences itself to improve research and strategies in the different branches of the veterinary area, and the second aspect is related to the possibility of data management harmonization to improve scientific cooperation.