Location: Foreign Animal Disease Research2013 Annual Report
1a. Objectives (from AD-416):
The objective of this collaborative agreement is to gain a better understanding of specific immune response to Foot-and-Mouth Disease Virus (FMDV) infection and vaccination and to identify the genetic basis of animals with high and low responder phenotypes. The objectives are: 1. to describe the early steps of the specific immune response against FMDV infection, 2. to describe the immune response elicited by inactivated FMDV vaccination, and 3. to determine the heritability of the response to FMDV vaccination in cattle populations.
1b. Approach (from AD-416):
1. The early steps of specific immune response against FMDV infection will be done through infection by aerosol inoculation delivery route and subsequent virus detection of respiratory tissues through immunostaining and real-time RT-PCR will be done. Replication sites will be correlated to anti-FMDV antibody-producing cells and studied. 2. The immune response elicited by inactivated FMDV vaccination will be studied. Cells responsible for antibody production will be determined through ELISpot assay and analyzed for protective response elicted by inactivated FMDV vaccines. These cells will genotyped with the aim of correlating host genotype with host resistance/recovery after experimental infection or induction of protection post vaccination. Results obtained from in vivo experiments will then be compared to in vitro responses. 3. The heritability of response to FMDV vaccination will be conducted studies of vaccinated bovine populations in Argentina with known pedigree. Estimates of heritability will be calculated to assess host genetic influence to FMDV vaccination response. These estimates will be used to assess merit of further efforts to identify bovine strains purported to demonstrate enhanced levels of innate resistance to FMDV. This will determine if selection for host resistance is possible and if significant gentetic differentiation is possible to identify.
3. Progress Report:
The aim of this project is to better understand the specific immune response to foot and mouth disease virus (FDMV) infection and vaccination and to identify the genetic basis of animals with high and low responder phenotypes. The project focuses on two main objectives: 1) To describe the early steps of the specific immune response against the FMDV infection in naïve and vaccinated cattle and; 2) To determine the heritability of the response to FMDV vaccination in cattle populations. Studies were completed for objective 1 inclusive of (1) the assaying the seroneutralizing activity of the FMDV-specific antibodies found at systemic level, (2) conducted studies of viremia in the serum samples of the vaccinated-infected animals, and (3) the establishment of a FMDV-specific B-cell memory assay. Results of these studies indicate that the FMDV-specific antibody secreting cells (ASC) could be detected in lymph nodes from respiratory tract since 7 days after intramuscular administration of a high-payload FMDV-inactivated oil vaccine. Also, presence of vaccine-induced FMDV-specific memory B-cells was evidenced in these tissues after oronasal challenge performed in these vaccinated cattle at 30 days post vaccination (dpv). In objective 2, the heterogeneity in the antibody response of cattle primo-vaccinated against FMD were quantified and its association with the genetic background in Holstein and Jersey sires was studied. A total of 377 FMDV seronegative calves, 122 and 255 calves from 16 and 15 Holstein and Jersey sires, respectively, were included in the study. Samples were taken the day prior to primo-vaccination and 45 dpv. Animals received commercial tetravalent FMD single-emulsion oil vaccines formulated with inactivated FMDV. Total FMDV-specific antibody responses were studied against 3 viral strains included in the vaccine and antibody titers were determined. Three linear hierarchical mixed regression models, one foreach strain, were formulated based on the dependent variables. Results of these studies indicate that breed may have a significant effect in the humoral immune response elicited after immunization with high-potency commercial FMD vaccines. Progeny of sires of Jersey breed developed a humoral response 45days post-primo vaccination which was significantly lower than Holstein sires’ offspring. No differences were found for calves derived from sires within the same breed. Analyses were carried out independently for three vaccine strains included in the formulation and results were similar in all cases. The significant accomplishments include; 1. The development of FMDV-specific ASC and interferon gamma – ELISpot assays to characterize local adaptive humoral responses induced in the bovine respiratory tract after FMDV infection. No previous references to these assays were described in the literature. 2. A detailed description of actual local responses elicited at early times after experimental oronasal FMDV-infection in naïve and vaccinated cattle using both techniques mentioned above. 3. A description of the presence of memory B-cells in the respiratory tract lymph nodes after intramuscular immunization with high-potency commercial FMD vaccines. 4. Results indicating that no differences were detected in the systemic antibody response induced at 45 dpv by high-potency commercial FMD vaccines among calves derived from sires of the same breed. The mean antibody titers differed only for calves from different breeds (Jersey vs. Holstein). No technologies have been transferred during this period. Publications for FY 2013 include: Early adaptive immune responses in the respiratory tract of foot and mouth disease-infected cattle. J. Pega, D. Bucafusco, S. Di Giacomo, JM. Schammas, D. Malacari, A. Capozzo, J. Arzt, C. Pérez-Beascoechea, E. Maradei, LL. Rodríguez, MV. Borca, M. Pérez-Filgueira. 2013, J Virol 87: 2489-95. Heterogeneity in the antibody response to foot-and-mouth disease primo vaccinated calves. S. Di Giacomo (*); B. Brito (*); A. M. Perez; D. Bucafusco; J. Pega; L. Rodríguez; M. Borca and M. Pérez-Filgueira. 2013, Transboundary and Emerging Diseases (in press). 2012 Meeting of the European Commission for the Control of Foot-and-Mouth Disease (EuFMD) “Appliance of science in the progressive control of FMD” held in Jerez de la Frontera, Spain, Octuber 29 -31, 2012 (“Adaptative immune responses in the respiratory tract of FMD-vaccinated cattle after oronasal infection” J. Pega, S. Di Giacomo, D. Bucafusco, J. Schammas, D. Malacari, G. Stafforini, A. Capozzo, LL. Rodríguez, MV. Borca, M. Pérez-Filgueira).