126
|
Kesik M, Saczyńska V, Szewczyk B, Płucienniczak A. Inclusion bodies from recombinant bacteria as a novel system for delivery of vaccine antigen by the oral route. Immunol Lett 2004; 91:197-204. [PMID: 15019290 DOI: 10.1016/j.imlet.2003.12.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2003] [Revised: 12/03/2003] [Accepted: 12/07/2003] [Indexed: 11/30/2022]
Abstract
A fragment of non-glycosylated E2 antigen of classical swine fever virus (CSFV), lacking the trans-membrane anchor (TM-) of the native glycoprotein, was produced in recombinant Escherichia coli strain BL21(DE3) in the form of inclusion bodies. These inclusion bodies isolated from the bacteria cells were administrated orally to mice twice at either 10 or 50 microg per dose. Each mouse fed with inclusion bodies carrying the E2 antigen responded with plasma antibodies and/or fecal IgA at least once during the entire investigation. Our study showed the capacity of inclusion bodies to induce both systemic and mucosal responses as well as to evoke relatively-long mucosal memory when fed to mice at low-number vaccination schedule and without any adjuvant. We propose the use of inclusion bodies for oral vaccination as an alternative to artificial systems for delivery of recombinant antigens by the oral route. Very few steps are needed to obtain an antigen ready for use as a vaccine. The procedure is easy and inexpensive and can be used for development of vaccine against classical swine fever.
Collapse
|
127
|
Dewulf J, Laevens H, Koenen F, Mintiens K, de Kruif A. Efficacy of E2-sub-unit marker and C-strain vaccines in reducing horizontal transmission of classical swine fever virus in weaner pigs. Prev Vet Med 2004; 65:121-33. [PMID: 15488266 DOI: 10.1016/j.prevetmed.2004.05.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2003] [Revised: 04/26/2004] [Accepted: 05/04/2004] [Indexed: 11/26/2022]
Abstract
At present, two types of vaccines against classical swine fever (CSF) virus are commercially available: E2 sub-unit marker vaccines and the conventional attenuated live C-strain vaccines. To evaluate the reduction of the horizontal virus transmission, three comparable experiments were carried out in which groups of weaner pigs (vaccinated with a marker vaccine or a C-strain vaccine) were challenged with CSF virus at 0, 7, and 14 days post-vaccination (dpv). Virus transmission was prevented totally when the challenge occurred at 14 dpv with an E2-marker vaccine (0/12 contact pigs positive in virus isolation (VI); R = 0 (0; 1.5)). At 7 dpv, transmission was reduced slightly (5/12 contact pigs positive in VI; R = 1.0 (0.3; 3.0)), whereas at 0dpv, vaccination had no effect on transmission (10/12 contact pigs positive in VI; R = 2.9 (1.5; 10.8)). In the C-strain-vaccinated pigs, no virus transmission was detected even when the challenge was performed at the same day as the vaccination (0/12 contact pigs positive in VI; R = 0 (0; 1.5)).
Collapse
|
128
|
Kaden V, Lange E. Development of maternal antibodies after oral vaccination of young female wild boar against classical swine fever. Vet Microbiol 2004; 103:115-9. [PMID: 15381274 DOI: 10.1016/j.vetmic.2004.07.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2003] [Revised: 05/28/2004] [Accepted: 07/01/2004] [Indexed: 11/25/2022]
Abstract
An experimental study was performed to investigate the development of maternal antibodies after oral immunisation of young female wild boar against classical swine fever (CSF) using C-strain vaccine. Our results demonstrated that maternal antibodies do not persist in the offspring for more than 3 months. Based on the neutralising serum antibody titres, we assume that piglets of wild sows vaccinated orally twice or immunised once a long time before conception have protective antibodies for approximately 2 months. Furthermore, it seems that the level and the duration of maternal antibodies in the offspring are depend on the age of the female animals at the moment of vaccination as demonstrated in our experiment. The recent vaccination procedure consists of three double vaccinations in spring, summer and autumn. Especially vaccinations in summer and autumn could be crucial for transfer of high maternal antibody titres to the offspring.
Collapse
|
129
|
Wu M, Gao R, Meng M, Li J, Tang M, Tan M, Shen Y, Wang L, Yin X, Wu X, Xie H, Liu S. Regulating effects of porcine interleukin-6 gene and CpG motifs on immune responses to porcine trivalent vaccines in mice. Res Vet Sci 2004; 77:49-57. [PMID: 15120952 DOI: 10.1016/j.rvsc.2003.11.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2003] [Indexed: 10/26/2022]
Abstract
In order to develop novel immunoadjuvants to boost immune response of conventional vaccines, experiments were conducted to investigate the regulating effects of porcine interleukin-6 gene and CpG motifs as the molecular adjuvants on immune responses of mice that were co-inoculated with trivalent vaccines against Swine fever, the Pasteurellosis and Erysipelas suis. Synthetic oligodeoxynuleotides containing CpG motifs were ligated into pUC18, forming recombinant pUC18-CpG plasmid. Eukaryotic plasmid expressing porcine interleukin-6 (VPIL-6) were also constructed as molecular adjuvants in an attempt to enhance levels of immune responses of mice co-administered with the trivalent vaccines in this paper. The cellular and humoral immune responses of mice were systematically analysed, and the experimental results were observed that the number of white blood cells, monocytes, granuloytes and lymphocytes significantly increased, respectively, in the mice immunized with VPIL-6, compared with those of the control; the IgG content and titre of specific antibodies to the trivalent vaccine mounted remarkably in the sera from the VPIL-6 vaccinated mice; the proliferation of lymphocytes and induced IL-2 activities were significantly increased in the vaccinated groups. The above-mentioned immune responses of mice co-inoculated with pUC18-CpG plasmid were significantly stronger than those of co-inoculated with pUC18 plasmid, suggesting that the immunostimulatory effect of oligodeoxynuleotides CpG is closely connected with the number of CpG motifs. These results suggest that the porcine IL-6 gene and CpG motifs could be employed as effective immunoadjuvants to elevate immunity to conventional vaccines.
Collapse
|
130
|
Kaden V, Lange E, Riebe R, Lange B. Classical Swine Fever Virus Strain 'C'. How Long is it Detectable After Oral Vaccination? ACTA ACUST UNITED AC 2004; 51:260-2. [PMID: 15458487 DOI: 10.1111/j.1439-0450.2004.00766.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To determine the persistence period of C-strain vaccine virus in immunized animals, domestic pigs and wild boars were vaccinated orally and killed on different days post vaccinationem (dpv). Tissue samples were taken at necropsy from both species for detection of C-strain virus. From domestic pigs nasal swabs and faeces were also collected. During the investigation period (2-12 dpv) vaccine virus could never be detected in nasal secretions and in faeces of vaccinated domestic pigs. In contrast, C-strain virus was found in organs until day 8 pv in domestic pigs and until day 9 pv in wild boars. Whereas in domestic pigs virus was detected in tonsils, Ln. mandibularis or in spleen, in wild boar it only was found in tonsils. We conclude that C-strain vaccine virus is not detectable in wild boars longer than 10-12 days after intake of the vaccine baits.
Collapse
|
131
|
Reimann I, Depner K, Trapp S, Beer M. An avirulent chimeric Pestivirus with altered cell tropism protects pigs against lethal infection with classical swine fever virus. Virology 2004; 322:143-57. [PMID: 15063124 DOI: 10.1016/j.virol.2004.01.028] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2003] [Revised: 11/25/2003] [Accepted: 01/24/2004] [Indexed: 11/26/2022]
Abstract
A chimeric Pestivirus was constructed using an infectious cDNA clone of bovine viral diarrhea virus (BVDV) [J. Virol. 70 (1996) 8606]. After deletion of the envelope protein E2-encoding region, the respective sequence of classical swine fever virus (CSFV) strain Alfort 187 was inserted in-frame resulting in plasmid pA/CP7_E2alf. After transfection of in vitro-transcribed CP7_E2alf RNA, autonomous replication of chimeric RNA in bovine and porcine cell cultures was observed. Efficient growth of chimeric CP7_E2alf virus, however, could only be demonstrated on porcine cells, and in contrast to the parental BVDV strain CP7, CP7_E2alf only inefficiently infected and propagated in bovine cells. The virulence, immunogenicity, and "marker vaccine" properties of the generated chimeric CP7_E2alf virus were determined in an animal experiment using 27 pigs. After intramuscular inoculation of 1 x 10(7) TCID(50), CP7_E2alf proved to be completely avirulent, and neither viremia nor virus transmission to contact animals was observed; however, CSFV-specific neutralizing antibodies were detected from day 11 after inoculation. In addition, sera from all animals reacted positive in an E2-specific CSFV-antibody ELISA, but were negative for CSFV-E(RNS)-specific antibodies as determined with a CSFV marker ELISA. After challenge infection with highly virulent CSFV strain Eystrup, pigs immunized with CP7_E2alf were fully protected against clinical signs of CSFV infection, viremia, and shedding of challenge virus, and almost all animals scored positive in a CSFV marker ELISA. From our results, we conclude that chimeric CP7_E2alf may not only serve as a tool for a better understanding of Pestivirus attachment, entry, and assembly, but also represents an innocuous and efficacious modified live CSFV "marker vaccine".
Collapse
|
132
|
Terzić S, Jemersić L, Lojkić M, Sver L, Valpotić I, Orsolić N, Humski A, Cvetnić Z. Leukocyte subsets and specific antibodies in pigs vaccinated with a classical swine fever subunit (E2) vaccine and the attenuated ORF virus strain D1701. Acta Vet Hung 2004; 52:151-61. [PMID: 15168746 DOI: 10.1556/avet.52.2004.2.3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Total white blood cell (WBC) counts and percentages of CD4a+, CD8a+, CD5a+, CD45RA+, CD45RC+, wCD21+ and SWC3a+ cells in the peripheral blood of pigs were analysed in this study. Blood samples were collected before and on days 4, 10, 21 and 28 after vaccination. Group 1 pigs were vaccinated with a subunit E2 vaccine (gp E2 32 microg/dose), and Group 2 received a subunit vaccine combined with an attenuated ORF virus strain D1701 10(6.45) TCID50/dose. Control pigs received a placebo. The total WBC count and percentage of particular cell types were within the normal range in vaccinated and control pigs. Although the mechanism of attenuated ORF virus activity is not clear, changes were observed in CD4a+, CD5a+, CD8a+, CD45RA+ and CD45RC+ cells in pigs that received the combination of a subunit vaccine and ORF virus. However, the percentage of wCD21+ and SWC3a+ did not differ significantly from that recorded in pigs given only the subunit vaccine. At days 4 and 10 the number of pigs positive to E2 antibodies was higher in the group that received the subunit vaccine and ORF virus than in pigs vaccinated with the subunit vaccine only. A higher percentage of memory cells (CD45RC+) as well as Th and Tc lymphocytes in pigs that received the ORF virus and the subunit vaccine could be ascribed to a nonspecific influence of the ORF virus on the development (through cognate interactions between T and B cells) and the duration (presumed according to the finding of the clonal expression of memory cells) of humoral immunity (assessed by a higher number of seropositive pigs in this group). This seems likely since the proportion of these cells was found to be lower in the pigs that received E2 vaccine only.
Collapse
|
133
|
Mayer D, Hofmann MA, Tratschin JD. Attenuation of classical swine fever virus by deletion of the viral N(pro) gene. Vaccine 2004; 22:317-28. [PMID: 14670312 DOI: 10.1016/j.vaccine.2003.08.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have reported earlier that replacement of the N(pro) gene of classical swine fever virus (CSFV) by the murine ubiquitin gene only slightly affects the characteristics of virus replication in the porcine kidney cell line SK-6 [J. Virol. 72 (1998) 7681]. Here, for the moderately virulent CSFV strain Alfort/187 as well as for the highly virulent strain Eystrup we show that the respective N(pro)-deleted viruses are attenuated. Vaccination of pigs with either of the two deletion mutants resulted in the induction of a strong antibody response. Animals were protected against challenge with a lethal dose of highly virulent CSFV indicating that N(pro) deletion mutants are excellent candidates for a modified live virus vaccine. A chimeric virus obtained by replacement of the N(pro) gene in the Eystrup virus by the corresponding sequence of the avirulent CSFV vaccine strain Riems resulted in a virus that was highly virulent. This indicates that the virulence of CSFV correlates with the presence of N(pro) and also suggests that N(pro) is not responsible for the varying virulence observed between individual strains of CSFV.
Collapse
|
134
|
Klinkenberg D, Everts-van der Wind A, Graat EAM, de Jong MCM. Quantification of the effect of control strategies on classical swine fever epidemics. Math Biosci 2004; 186:145-73. [PMID: 14583170 DOI: 10.1016/j.mbs.2003.08.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Emergency vaccination during an epidemic of classical swine fever virus (CSFV) has become a serious option because of the ethical problems of strategies with massive culling and the availability of a marker vaccine that reduces virus transmission. Here we present a model of between-herd CSFV transmission, which quantifies the effect of control strategies with and without vaccination. We estimate the model parameters from data of the Dutch CSFV epidemic of 1997/1998. With the model, a set of control strategies is compared, consisting of five control measures in several combinations. Consequently, the following general requirements of successful strategies can be formulated. First, to achieve extinction of a CSFV epidemic, transmission through transport should be prevented and the indirect virus transmission, i.e. all transmission not through animal contacts, should at least be halved, either by vaccination or by culling of the susceptible pig population. Second, to minimize the size and duration of an epidemic, the extinction requirements should be met quickly and indirect virus transmission should be reduced by far more than a half. Although the origin of the model parameters let the requirements in fact be only applicable for the south-eastern part of the Netherlands, it is argued that epidemics in other areas will not need stricter control strategies.
Collapse
|
135
|
Kaden V, Lange E, Steyer H. Does multiple oral vaccination of wild boar against classical swine fever (CSF) have a positive influence on the immunity? DTW. DEUTSCHE TIERARZTLICHE WOCHENSCHRIFT 2004; 111:63-7. [PMID: 15032263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
We studied the efficacy of multiple vaccinations of wild boar against classical swine fever (CSF) using a C-strain vaccine. The study consisted of two experiments. In the first experiment, 7 to 8 months old animals were vaccinated either three or four times at an interval of 7 days or twice at an interval of 14 or 28 days. In the second experiment, the efficacy of oral immunisation in young boars (3 months old) was examined after fivefold vaccination at intervals of 14 or 28 days. Independently of the immunisation scheme all wild boar developed neutralising antibodies. An evaluation of the antibody titres 28 days after the initial vaccine application showed that single vaccination and triple immunisation at an interval of 7 days induced the highest antibody titres (X > or = 1/80). In multiple vaccinated young boars (vaccinated at intervals of 14 or 28 days) the third vaccination led to a slight reduction or to an only moderate increase of the antibody titre. In a challenge study after the fifth vaccination all wild boar were protected (no viraemia, no virus excretion, no post-mortem virus detection in organs). This was confirmed by the fact that sentinel animals were not affected. Although other immunisation schemes also were effective, booster vaccination at an interval of 28 days is recommended as basic procedure for eradication of CSF in wild boar. Triple vaccination might also be used at the beginning of the control measures.
Collapse
|
136
|
Vannier P. Development of new concepts in vaccines and their effects on the control of infectious diseases (classical swine fever in particular). DEVELOPMENTS IN BIOLOGICALS 2004; 119:235-41. [PMID: 15742634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Molecular biology and technological advances in DNA recombination have ushered in a new era in vaccinology. In particular, "deleted" vaccines have emerged over the past 10 years. The first such vaccines were used to protect pigs against Aujeszky's disease. The same principles were subsequently applied to the development of vaccines against classical swine fever (CSF), relaunching the debate on whether to use sanitary or medical measures. The decision about the measures to be applied depends on several criteria and factors such as the capabilities of the vaccines to be used in an emergency situation and the local epidemiological situation. Under the light of the last CSF serious epizootic which appeared in Europe in 1997, the effects of the different types of measures are discussed.
Collapse
|
137
|
Abstract
Classical swine fever (CSF) is a serious and contagious viral disease of pigs and wild boar with a widespread worldwide distribution. The immunopathology of the disease is poorly understood, but the ability of the CSF virus to infect cells without triggering apoptosis and to kill uninfected cells is probably highly significant. The virus may be spread by various direct and indirect methods, but in most cases the exact mechanisms involved in local spread between farms are not known. Excellent diagnostic tools and typing methods are available, but tests that could be performed on-farm, in pre-clinically infected pigs or on meat would also be advantageous. A more complete picture of the viruses circulating in different parts of the world is needed. There is great interest to develop and use marker vaccines for the control of CSF in domestic pigs and in wild boar. Epidemiological modelling is increasingly used to evaluate control options.
Collapse
|
138
|
Hammond JM, Jansen ES, Morrissy CJ, Hodgson ALM, Johnson MA. Protection of pigs against ‘in contact’ challenge with classical swine fever following oral or subcutaneous vaccination with a recombinant porcine adenovirus. Virus Res 2003; 97:151-7. [PMID: 14602208 DOI: 10.1016/j.virusres.2003.08.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A recombinant porcine adenovirus expressing the classical swine fever virus (CSFV) gp55 gene (rPAdV-gp55) was administered to commercially available outbred pigs via the subcutaneous or oral route and their susceptibility to 'in contact' challenge with classical swine fever determined. Animals vaccinated subcutaneously with a single dose of recombinant vaccine and challenged by 'in contact' exposure were protected from disease, whereas pigs given an equivalent single oral dose did not survive challenge. However, pigs given two oral doses of rPAdV-gp55, 22 days apart, were completely protected from disease. In addition, two doses of rPAdV-gp55 given subcutaneously was shown to boost CSFV neutralising antibody compared with a single dose, but neither a single dose nor two doses given orally induced detectable neutralising antibody responses.
Collapse
|
139
|
Abstract
There are two types of classical swine fever vaccines available: the classical live and the recently developed E2 subunit vaccines. The live Chinese strain vaccine is the most widely used. After a single vaccination, it confers solid immunity within a few days that appears to persist lifelong. The E2 subunit vaccine induces immunity from approximately 10-14 days after a single vaccination. The immunity may persist for more than a year, but is then not complete. The Chinese strain vaccine may establish a strong herd immunity 1-2 weeks earlier than the E2 vaccine. The ability of the Chinese vaccine strain to prevent congenital infection has not been reported, but the E2 subunit vaccine does not induce complete protection against congenital infection. Immunological mechanisms that underlie the protective immunity are still to be elucidated. Both types of vaccine are considered to be safe. A great advantage of the E2 subunit vaccine is that it allows differentiation of infected pigs from vaccinated pigs and is referred to as a DIVA vaccine. However, the companion diagnostic E(rns) ELISA to actually make that differentiation should be improved. Many approaches to develop novel vaccines have been described, but none of these is likely to result in a new DIVA vaccine reaching the market in the next 5-10 years. Countries where classical swine fever is endemic can best control the infection by systematic vaccination campaigns, accompanied by the normal diagnostic procedures and control measures. Oral vaccination of wild boar may contribute to lowering the incidence of classical swine fever, and consequently diminishing the threat of virus introduction into domestic pigs. Free countries should not vaccinate and should be highly alert to rapidly diagnose any new outbreak. Once a new introduction of classical swine fever virus in dense pig areas has been confirmed, an emergency vaccination programme should be immediately instituted, for maximum benefit. The question is whether the time is ripe to seriously consider global eradication of classical swine fever virus.
Collapse
|
140
|
Li H, Yang H. Infection of porcine reproductive and respiratory syndrome virus suppresses the antibody response to classical swine fever virus vaccination. Vet Microbiol 2003; 95:295-301. [PMID: 12935755 DOI: 10.1016/s0378-1135(03)00158-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The effects of porcine reproductive and respiratory syndrome virus (PRRSV) infection on the antibody response to vaccination with classical swine fever (CSF) vaccine in piglets were investigated. Piglets were inoculated intranasally with the PRRSV BJ-4 strain, and then vaccinated intramuscularly with CSF vaccine 2 days later. Control animals were either vaccinated with CSF vaccine or infected with PRRSV alone. Time course of the antibody response against either PRRSV or CSF vaccine was measured. In animals infected with PRRSV prior to CSF vaccination, the antibody response to CSF vaccine was significantly lower than that observed in animals treated with CSF vaccination alone, especially during 3-5 weeks after vaccination. At the same time, no significant difference in serum PRRSV antibody level was observed between the animals treated with both PRRSV and CSF vaccine and the animals treated with PRRSV alone. These results suggested that the reduced antibody response against CSF vaccine observed in PRRSV-infected animals might be related to the higher prevalence of CSF in PRRSV prevalent farms in China.
Collapse
|
141
|
Kaden V, Lange E, Steyer H, Bruer W, Langner CH. Role of birds in transmission of classical swine fever virus. ACTA ACUST UNITED AC 2003; 50:357-9. [PMID: 14535936 DOI: 10.1046/j.1439-0450.2003.00670.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Active transmission of classical swine fever virus (CSFV) was studied in six birds (five ravens, one hooded crow) and two laying hens. Cloacal swabs, blood and organs of birds and hens as well as blood and organ samples of pigs which had been fed with faeces derived from CSFV infected birds or which had come in contact with faeces of infected hens were negative for CSFV. None of the animals seroconverted during the study. This result demonstrates that active virus transmission by these animals is unlikely. Dissemination of CSFV from wild boar to domestic pigs is discussed.
Collapse
|
142
|
Kaden V, Renner C, Rothe A, Lange E, Hänel A, Gossger K. Evaluation of the oral immunisation of wild boar against classical swine fever in Baden-Württemberg. BERLINER UND MUNCHENER TIERARZTLICHE WOCHENSCHRIFT 2003; 116:362-7. [PMID: 14526465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
The oral immunisation of wild boar against classical swine fever (CSF) in Baden-Württemberg is described and evaluated. The bait vaccine based on the CSF virus (CSFV) strain "C" proved to be safe in wild boar of all age classes. The modified immunisation procedure consisting of three double vaccinations per year was very effective. CSFV was not detected beyond the second immunisation campaign. The average rate of seropositive wild boar diagnosed over all immunisation periods was 49.2%. The seroprevalence rate increased significantly during the first year of immunisation and reached its maximum after the third vaccination period with 72% antibody positive animals. The higher percentage of seropositive young boars in this field trial compared to the seroprevalence rates in this age class in other field trials in Germany may be attributed to the new vaccination scheme. Factors that may be responsible for the decreased herd immunity after the fourth or sixth immunisation period are discussed.
Collapse
|
143
|
Piriou L, Chevallier S, Hutet E, Charley B, Le Potier MF, Albina E. Humoral and cell-mediated immune responses of d/d histocompatible pigs against classical swine fever (CSF) virus. Vet Res 2003; 34:389-404. [PMID: 12911856 DOI: 10.1051/vetres:2003013] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
A better understanding of cell-mediated immune responses to classical swine fever virus (CSFV) is essential for the future development of improved vaccines. We analyzed the generation of cell-mediated and humoral immune responses in d/d histocompatible pigs following CSFV infection or vaccination. Viral infection induced high T cell responses with high primary and secondary CTL activity correlated with high IFN-gamma production, whereas vaccination with a live vaccine followed by infection mainly induced neutralizing antibody but low cell-mediated responses. Moreover, high IgG1 response was associated with high IFN-gamma response following infection whereas a weak IFN-gamma response was related to a good IgG2 response but a low IgG1 production. These data could reflect Th1/Th2-like balance of immune responses depending upon immunization protocols, which has not yet been described in the pig. T-cell responses to CSFV were evidenced by CSFV-specific CD25 upregulation on CD4-CD8+, but not on CD4+CD8- cells, which further illustrated the importance of CTL responses after infection. Our results indicated that generation of cell-mediated immune responses was much higher following intranasal/oral CSFV infection than after intramuscular vaccination, which implies that the capacity of new CSFV vaccines to induce higher T-cell responses should be considered.
Collapse
|
144
|
Terzić S, Sver L, Valpotić I, Jemersić L, Lojkić M, Miletić Z, Orsolić N, Forsek J. Proportions and phenotypic expression of peripheral blood leucocytes in pigs vaccinated with an attenuated C strain and a subunit E2 vaccine against classical swine fever. JOURNAL OF VETERINARY MEDICINE. B, INFECTIOUS DISEASES AND VETERINARY PUBLIC HEALTH 2003; 50:166-71. [PMID: 12916689 DOI: 10.1046/j.1439-0450.2003.00652.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The influence of an attenuated classical swine fever virus C strain vaccine and a subunit E2 vaccine against classical swine fever on the peripheral blood leucocyte proportion and phenotypic expression in 12-week-old pigs was studied. The C strain was amplified in minipig kidney cell culture and final product contained 10(4 +/- 0.15) TCID50/ml, while the subunit vaccine contained 32 microg per dose of gp E2. Haematological findings showed that the vaccines did not cause leucopenia or lymphocytopenia and the number of neutrophils and eosinophils during the observation period was within physiological range. The results of the proportion of CD4a+, CD5a+, CD8a+, wCD21+, CD45RA+, CD45RC+ , non-T non-B, SWC3a+ and CD11b+ cells were gained by single-colour flow cytometry. At the end of the trial a significantly increase of percentage of CD4+, CD5a+, CD8+, wCD21+ cells has been found in pigs that received the subunit vaccine and the percentage of CD4+, CD5a+, CD8+, CD45RA+ and CD45RC+ cells was higher in pigs that received the attenuated vaccine. Twenty-eight days after vaccination the percentage of CD4+, CD45RA+ and CD45RC+ was significantly higher in pigs vaccinated with the C strain than in pigs vaccinated with the subunit vaccine. In contrary, the percentage of the wCD21- cells was higher in pigs that received the subunit vaccine. Statistically higher values of SWC3a+ and lower values of CD11b+ cells was observed in pigs that received the attenuated vaccine than in pigs vaccinated with the subunit vaccine. Taken altogether, our results showed that the subunit vaccine produced a better stimulation of B cells and CD11b+ monocytes/macrophages /granulocytes/NK cells, whereas the attenuated vaccine induced a higher response of Th cells, naive/memory cells and macrophages/neutrophils. Thus, both vaccines were able to influence the porcine immune system, by activating different subsets of the immune effector/accessory cells.
Collapse
|
145
|
Terzić S, Jemersić L, Lojkić M, Madić J, Grom J, Toplak I, Sver L, Valpotić I. Comparison of antibody values in sera of pigs vaccinated with a subunit or an attenuated vaccine against classical swine fever. Vet Res Commun 2003; 27:329-39. [PMID: 12872833 DOI: 10.1023/a:1024040326550] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Ten pigs, aged 85 days, were vaccinated with a subunit vaccine containing 32 microg of classical swine fever virus glycoprotein E2 (gp E2) (group 1), and a further 10 pigs were vaccinated with a C strain vaccine (10(4+/-0.15) TCID50/ml), produced by amplification in minipig kidney (MPK) cell culture (group 2). Nine non-vaccinated pigs served as a control group (group 3). Serum samples were collected before (day 0) and at 4, 10, 21 and 28 days after vaccination and were analysed by two commercially available enzyme immunoassays and by a neutralizing peroxidase-linked assay (NPLA). At the same times, peripheral blood was taken for determining the total leukocyte count and the body temperature was taken daily. Antibodies were not detected in serum samples collected before vaccination (day 0), and no side-effects that could be connected with vaccination were observed during the trial. Ten days after vaccination 6/10 pigs vaccinated with the subunit vaccine were seropositive. On days 21 and 28, the ratios of serologically positive to vaccinated pigs were 9/10 and 10/10, respectively. Four of the ten pigs that were vaccinated with the C strain vaccine were positive on day 21 and 9/10 on day 28. However, the results of the NPLA showed that only 4/10 pigs had an antibody titre > 1:32 at the end of the trial in both the vaccinated groups, even though the subunit vaccine initiated an earlier and higher level of neutralizing antibodies than the vaccine produced from the C strain. Challenge was performed 28 days after vaccination on four randomly selected pigs from both vaccinated groups. The pigs survived the challenge without showing any clinical signs of classical swine fever (CSF), while two nonvaccinated control pigs died on the 10th and 12th days after infection.
Collapse
|
146
|
Suradhat S, Damrongwatanapokin S. The influence of maternal immunity on the efficacy of a classical swine fever vaccine against classical swine fever virus, genogroup 2.2, infection. Vet Microbiol 2003; 92:187-94. [PMID: 12488082 DOI: 10.1016/s0378-1135(02)00357-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In Thailand, where vaccination is routinely employed, there has been an increased incidence of chronic classical swine fever (CSF) outbreaks during the past decade. The major causative virus has been identified to be the moderate virulence, classical swine fever virus (CSFV) of the genogroup 2.2. An investigation was made into the efficacy of a CSF vaccine against this genogroup 2.2 challenge. Five-week-old pigs, grouped by their level of passive antibody titer were immunized with lapinized Chinese-strain CSF vaccine and challenged with CSFV genogroup 2.2, 13 days after vaccination. The group containing passive titers of lower than 64 at the time of immunization, had significantly higher number of CSFV-specific IFN-gamma secreting cells and was completely protected against the challenge. Interestingly, both cellular and antibody responses were inhibited in the pigs with the higher passive titer. Furthermore, following challenge, CSFV could be isolated from 50% of the pigs in this group. It was demonstrated that the CSF vaccine could induce complete protection in pigs, provided that the maternal derived titer at the time of vaccination was lower than 64. The result implied that an increase in CSFV outbreaks might be due to the inappropriate timing of vaccination as well as the nature of the CSFV genogroup 2.2.
Collapse
|
147
|
Suradhat S, Thanawongnuwech R, Poovorawan Y. Upregulation of IL-10 gene expression in porcine peripheral blood mononuclear cells by porcine reproductive and respiratory syndrome virus. J Gen Virol 2003; 84:453-459. [PMID: 12560579 DOI: 10.1099/vir.0.18698-0] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Several lines of evidence suggest that porcine reproductive and respiratory syndrome virus (PRRSV) may have immunomodulatory effects on the host immune system. To determine the effect of PRRSV on cytokine production, a multiplex PCR was established. This allowed a semi-quantitative analysis of IFN-gamma, IL-2, IL-4, IL-10 and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene expression levels from porcine peripheral blood mononuclear cells (PBMCs). These results showed that both live and inactivated PRRSV predominantly upregulated IL-10 gene expression in porcine PBMCs. In addition, when PBMCs from pigs immunized previously with classical swine fever virus (CSFV) vaccine were cultivated with the recall antigen, CSFV, in the presence of PRRSV, significant upregulation of IL-10 gene expression and reduction of IFN-gamma gene expression were observed. These findings indicated that the presence of PRRSV in the culture could affect recall antigen response. This study implies that the induction of IL-10 production may be one of the strategies used by PRRSV to modulate host immune responses.
Collapse
|
148
|
Choi C, Chae C. Detection of classical swine fever virus in boar semen by reverse transcription-polymerase chain reaction. J Vet Diagn Invest 2003; 15:35-41. [PMID: 12580293 DOI: 10.1177/104063870301500108] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
A seminested reverse transcription-polymerase chain reaction (RT-PCR) was developed for the detection of classical swine fever virus (CSFV) in semen. Five boars were inoculated intranasally with CSFV isolate propagated in PK15 cells. Two boars inoculated with the supernatant of noninfected PK15 cells were kept as controls. Semen and serum samples were collected twice weekly for 63 days postinoculation (dpi). Samples were tested for the presence of antibodies to CSFV by an enzyme-linked immunosorbent assay and for the presence of CSFV nucleic acid by seminested RT-PCR. Antibodies to CSFV could be detected as early as 7 dpi in 1 boar, and all 5 infected boars were found positive by 14 dpi. CSFV from boar semen was infrequently identified by virus isolation compared with seminested RT-PCR. CSFV nucleic acid was detected in semen by seminested RT-PCR as early as 7 dpi in 3 infected boars and persistently thereafter in all 5 infected boars until 63 dpi. When separated fractions of CSFV-contaminated semen were analyzed by the seminested RT-PCR, the CSFV nucleic acid was detected mainly in seminal fluid and occasionally in nonsperm cells. CSFV antigen was also detected in nonsperm cells from semen smear by immunohistochemistry. Thus, infection via semen, specially through CSFV-infected seminal fluid, seems to be a major route of transmission of CSFV.
Collapse
|
149
|
Choi C, Chae C. Detection of classical swine fever virus in the ovaries of experimentally infected sows. J Comp Pathol 2003; 128:60-6. [PMID: 12531688 DOI: 10.1053/jcpa.2002.0607] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Six sows were infected intranasally with a Korean isolate of classical swine fever virus (CSFV). The distribution of virus in ovarian tissues was then assessed for 21 days by in-situ hybridization and immunohistochemistry. CSFV was detected in the ovaries between 7 and 21 days post-inoculation (dpi) by both methods, but the labelling was particularly intense and widespread at 7 dpi. CSFV nucleic acid and antigen were located almost exclusively within the cytoplasm of cells shown by haematoxylin and eosin staining to be macrophages, which were numerous in atretic follicles. Small numbers of CSFV nucleic acid-positive cells with distinctly round morphology and oval nuclei, resembling monocytes, were also observed in the blood vessels of sows at 7 and 14 dpi. CSFV nucleic acid and antigen were not observed in primordial, primary or secondary follicles from infected sows at 7, 14 or 21 dpi. The results suggest that CSFV replicates in circulating peripheral monocytes and gains access to ovarian tissues from the bloodstream, and that this contributes to the distribution of CSFV in macrophages throughout the atretic follicles.
Collapse
|
150
|
Moennig V, Floegel-Niesmann G, Greiser-Wilke I. Clinical signs and epidemiology of classical swine fever: a review of new knowledge. Vet J 2003; 165:11-20. [PMID: 12618065 DOI: 10.1016/s1090-0233(02)00112-0] [Citation(s) in RCA: 242] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Although classical swine fever (CSF) has been well known for decades and epidemics still occur, clinical diagnosis continues to cause problems for veterinary practitioners. This is due to the extensive differential diagnosis, further complicated by the emergence of new diseases such as porcine reproductive and respiratory syndrome (PRRS) and porcine dermatitis and nephropathy syndrome (PDNS). In addition, acute, chronic and prenatal courses of CSF have to be distinguished. As a cause of considerable economical losses within the EU, control of CSF requires knowledge of the primary outbreaks and spread of the disease. Genetic typing of CSF virus isolates has proved to be a potent method of supporting epidemiological investigations. Phylogenetic analysis of CSF virus strains and isolates originating from different continents has allowed three genetic groups and several subgroups within these groups to be distinguished. Whereas isolates belonging to group 3 seem to occur solely in Asia, all CSF virus isolates of the 1990s isolated in the EU belonged to one of the subgroups within group 2 (2.1, 2.2, or 2.3) and were clearly distinct from former CSF reference viruses, which belong to group 1. Within the EU, different strategies are followed for the eradication of CSF in domestic pigs and in wild boar. While a strict non-vaccination policy is followed for domestic pigs, eradication of the disease in wild boar is more complex, and oral immunisation together with special hunting strategies have been applied. Recently, marker vaccines with a companion discriminatory test designed to allow differentiation between vaccinated animals and animals having recovered from field virus infection have been developed. Preliminary studies indicated that the discriminatory tests had a reduced sensitivity and specificity. Further improvements are therefore necessary before marker vaccines can be considered for emergency use in EU Member States. Prevention of CSF remains the main objective within the EU.
Collapse
|