Comparison of efficacy of commercial one dose and two dose PCV2 vaccines using a mixed PRRSV–PCV2–SIV clinical infection model 2–3-months post vaccination
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, United States. Vaccine
(Impact Factor: 3.62).
02/2009; 27(7):1002-7. DOI: 10.1016/j.vaccine.2008.11.105
The study objectives were to compare the duration of immunity of commercially available, one and two dose, killed porcine circovirus type 2 (PCV2) vaccines. Sixty, 3.5-week-old pigs were randomly divided into six treatment groups: one dose vaccines (FDAH-1, BIVI-1), two dose vaccines (Intervet-2, FDAH-2), and non-vaccinated negative and positive controls. Tissue homogenate challenge was conducted 63 (two doses) or 84 (one dose) days post vaccination. Viremia was reduced by 78.5% in pigs vaccinated with one dose and by 97.1% in pigs vaccinated with two dose products and overall microscopic lymphoid lesions were reduced by 78.7% and 81.8%, respectively.
Available from: Shao-Lun Zhai
- "A number of field and experimental studies that were performed in some countries of North America, Europe and Asia indicated that commercial vaccines (based on genotype PCV2a) against PCV2 were effective in many aspects, including reducing the incidence of PMWS, the number of co-infections, the severity of lesions in lymphoid tissues [20-25], the level of PCV2 viraemia and the severity of microscopically-visible lesions [26-29] as well as improving average daily weight gain and feed conversion ratios [20-25]. However, due to the subsequent possible vaccination pressure, novel variant strains or genotypes (such as PCV1/2, PCV2d) emerged in Canadian and U.S. swine herds [30-32]. "
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ABSTRACT: Currently, porcine circovirus type 2 (PCV2) is considered the major pathogen of porcine circovirus associated-diseases (PCVAD) that causes large economic losses for the swine industry in the world annually, including China. Since the first report of PCV2 in 1998, it has been drawing tremendous attention for the government, farming enterprises, farmers, and veterinary practitioners. Chinese researchers have conducted a number of molecular epidemiological work on PCV2 by molecular approaches in the past several years, which has resulted in the identification of novel PCV2 genotypes and PCV2-like agents as well as the description of new prevalence patterns. Since late 2009, commercial PCV2 vaccines, including the subunit vaccines and inactivated vaccines, have already been used in Chinese swine farms. The aim of this review is to update the insights into the prevalence and control of PCV2 in China, which would contribute to understanding the epidemiology, control measures and design of novel vaccines for PCV2.
Available from: Angel González Wong
- "Phylogenetic analysis of the capsid gene revealed that the dominant PCV2 genotype in the vaccinated pool belonged to PCV2a, whilst in the non-vaccinated pool it belonged to PCV2b. This is especially interesting as all current vaccines are based on the PCV2a genotype, although these vaccines have been shown to induce cross-protective immunity (Fort et al., 2008; Opriessnig et al., 2009). "
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ABSTRACT: Vaccines against Porcine circovirus 2 (PCV2) are nowadays widely used to control the diseases caused by the virus. Although the vaccines are protecting pigs against the disease, they do not lead to sterilizing immunity and therefore infections with PCV2 continue in the farms. It is expected that due to high evolutionary rate, PCV2 can adapt fast to environmental pressures, like may be vaccination. The goal of this study was to elucidate the molecular variation of PCV2 in relation with vaccination. PCV2 variability was investigated from samples of infected pigs origin from five farms where vaccination has never been applied and two farms where pigs have been vaccinated at least for two years. For the genetic analysis full PCV2 genomes were amplified and subsequently pooled by vaccination status, from serum of 8 vaccinated, infected pigs and 16 non-vaccinated, infected pigs. Variability of viral populations was quantified using next generation sequencing and subsequent bioinformatics analysis. Number of segregating sites was similar in non-vaccinated (109) and vaccinated pool (96) but the distribution of these sites in the genome differed. Most notably, in the capsid gene number of segregating sites was observed only in non-vaccinated population. Based on the structural analysis, it is expected that some low frequency amino acids results in biologically low fit viruses. In contrary, D294 in Replicase represents a novel amino acid which was dominant and unique in vaccinated pool. This work shows that variable PCV2 populations are circulating in commercial farms and that this variability was different in samples obtained from vaccinating and non-vaccinating farms.
Available from: PubMed Central
- "The immune response evaluated under experimental and field conditions highlighted the involvement of both humoral and cellular immune responses in sustaining clinical protection. Specifically, studies on the efficacy of experimental/commercial vaccines in SPF (specific pathogen-free) or conventional animals experimentally challenged after 3-6 weeks with PCV2 strains showed the induction of virus-specific antibodies and IFN-γ secreting cells associated with the reduction of viremia, shedding and viral burden in tissues upon subclinical outcomes [23,26-33]. A study by Seo et al. showed that vaccination of conventional-experimentally infected piglets using an inactivated chimeric PCV1-2 vaccine induced increases of CD3+ and CD4+ cells in the blood and sustained higher CD4+ cell levels after infection . "
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ABSTRACT: Porcine circovirus type 2 (PCV2) vaccination represents an important measure to cope with PCV2 infection; however, data regarding the modulation of the immune cell compartment are still limited, especially under field conditions. This study is aimed at investigating the features of the cellular immune response in conventional piglets induced by vaccination using a capsid (Cap) protein-based PCV2 vaccine compared to unvaccinated animals when exposed to PCV2 natural infection. Immune reactivity was evaluated by quantifying peripheral cell subsets involved in the anti-viral response and characterizing the interferon-gamma (IFN-gamma) secreting cell (SC) responsiveness both in vivo and upon in vitro whole PCV2 recall. The vaccination triggered an early and intense IFN-gamma secreting cell response and induced the activation of peripheral lymphocytes. The early increase of IFN-gamma SC frequencies resulted in a remarkable and transient tendency to increased IFN-gamma productivity in vaccinated pigs. In vaccinated animals, soon before the onset of infection occurring 15-16 weeks post-vaccination, the recalled PCV2-specific immune response was characterized by moderate PCV2-specific IFN-gamma secreting cell frequencies and augmented productivity together with reactive CD4+CD8+ memory T cells. Conversely, upon infection, unvaccinated animals showed very high frequencies of IFN-gamma secreting cells and a tendency to lower productivity, which paralleled with effector CD4-CD8+ cytotoxic cell responsiveness. The study shows that PCV2 vaccination induces a long-lasting immunity sustained by memory T cells and IFN-gamma secreting cells that potentially played a role in preventing the onset of infection; the extent and duration of this reactivity can be an important feature for evaluating the protective immunity induced by vaccination.
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