Source: KANSAS STATE UNIV submitted to
DEVELOPMENT AND VALIDATION OF NOVEL DIAGNOSTIC TOOLS FOR RAPID AND EARLY DETECTION OF EMERGING INFECTION FROM ASFV VARIANTS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
ACTIVE
Funding Source
Reporting Frequency
Annual
Accession No.
1028186
Grant No.
2022-67015-36516
Cumulative Award Amt.
$300,000.00
Proposal No.
2021-11304
Multistate No.
(N/A)
Project Start Date
Sep 1, 2022
Project End Date
Feb 28, 2025
Grant Year
2022
Program Code
[A1181]- Tactical Sciences for Agricultural Biosecurity
Project Director
Wang, L.
Recipient Organization
KANSAS STATE UNIV
(N/A)
MANHATTAN,KS 66506
Performing Department
Anatomy & Physiology
Non Technical Summary
Rapid and early detection measures are extremely essential and useful for the prevention and control ofAfrican swine fever (ASF) before a safe and efficacious ASFvaccine is developed and commercially available. In this project, we will develop competitiveenzyme-linked immunosorbent assays(cELISAs) to test early antibodies induced by African swine fever virus (ASFV) infection by using our unique anti-ASFV monoclonal antibodies. We will develop a novel multiplex real-time PCR assays for accurate and reliable detection of emerging ASFV variants. In addition, we will secure clinical samples from field pigs naturally infected with ASFV in current ASF-affected countries to validate the ASF diagnostic tools developed by us and others. Successful completion of this project will reduce the impact of ASF, the highly lethal and contagious transboundary foreign swine disease, on the U.S. swine production system. The research will not only develop novel diagnostic tools for ASF control and prevention, but also position the Biosecurity Research Institute (BRI) at Kansas State University (KSU) as the leading institution in the United States with unique resources for validation of ASF diagnostic assays.
Animal Health Component
90%
Research Effort Categories
Basic
10%
Applied
90%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
31135991040100%
Knowledge Area
311 - Animal Diseases;

Subject Of Investigation
3599 - Swine, general/other;

Field Of Science
1040 - Molecular biology;
Goals / Objectives
The overall goal of this project is to develop novel diagnostic tests and provide uniqueresources for validation of African swine fever (ASF) diagnostic tools. Objectives of our research efforts include:Collect field clinical samples from pigs naturally infected with ASFV in commercial swine farms in Vietnam and the Philippines.Collect field clinical samples from ASF-free pigs in local farms in the United States.Transfer the collected clinical samples from Vietnam and the Philippines to the United States.Develop, optimize and validate cELISA system using p30 protein as the capture antigen and mAb3007 as the competitive antibody.Express CD2v protein with Baculovirus Expression System and generate anti-CD2v mAbs.Develop, optimize and validate cELISA system using CD2v protein as the capture antigen and anti-CD2v mAb as the competitive antibody.Develop, optimize and validate a reliable multiplex real-time PCR assay for ASFV variants testing.
Project Methods
We will conduct our project through the following ways:1.Secure field clinical samples from pigs naturally infected with ASFV in commercial swine farms in Vietnam and the PhilippinesWe plan to work with our collaborators in Vietnam and the Philippines to secure three types of tissue samples from pigs on commercial farms with ASF outbreaks in the first 6 months of this project: 1) Serum (from 10ml blood of each pig); 2) Dry blood (2x4 spots/pig) on filter paper card (QIAcard FTA Elute Micro, Qiagen); 3) Ear punch biopsy (6 pieces/pig).We plan to collect from at least 300 pigs from each country (80% pigs with clinical symptoms and 20% pigs without clinical symptoms) on swine farms with a new ASF outbreak. All ASF positive pigs will be confirmed by PCR testing.2.Secure field clinical samples from ASF-free pigs in local farms in the United StatesWe will work with local farms in Kansas to secure the known ASF negative field clinical samples including serum (from 10ml blood of each pig), dry blood on filter paper card (2x4 spots/pig), and ear punch biopsy (6 pieces/pig). We plan to collect from at least 100 pigs.All samples will be kept in ice during collection, in -80? freezer for storing and in dry ice during transportations.3. Develop and optimize cELISA system based on p30 and mAb3007Specific research priorities include 1) purify mAb3007 and label it with horseradish peroxidase (HRP); 2) determine optimal concentrations of the coating antigen and HRP-mAbs by systematic checkerboard titrations; 3) select optimal blocking buffer (nonfat powdered milk, fetal bovine serum, bovine serum albumin and other commercial available blocking solutions); 4) determine optimal dilutions of serum samples by testing serial dilutions of positive and negative reference serum samples; 5) determine optimal incubation conditions by comparing signal to noise ratios. 4.Develop and optimize cELISA system based on CD2v and anti-CD2v mAbSpecific research priorities include 1) Express CD2v protein with Baculovirus Expression System; 2) Genreate and identify the anti-CD2v mAbs that are specific to current epidemic strains;3) Purify and label the anti-CD2v mAbs with HRP; 4) establish and optimize the cELISA system.5. Validation of the cELISA systemsAfter successful development and optimization of cELISA systems, an adequate validation is necessary to make the assay suitable for routine use. Specific research priorities include: 1) establish the cut-off value of the cELISA systems by receiver-operating characteristic (ROC) analysis using known-positive (n ≥ 100) and known-negative (n ≥ 100) reference serum samples and field clinical serum samples; 2) validate the sensitivity of the cELISA systems by comparing them with the standard ELISA and IFAT; 3) validate the specificity of the cELISA systems by testing positive sera from pigs exposed to other ASFV isolates (i.e. genotype I and IX ASFV, which are commonly found in endemic countries in Africa), and other common swine pathogens (CSFV, PRRSV and pseudorabies virus) and bovine viral diarrhea virus; 4) validate the inter-assay and intra-assay repeatability for the cELISA systems by testing various field clinical serum samples.6. Develop and optimize the ASFV variants multiplex real-time PCR All available ASFV sequences (GenBank, ASFV sequence database of EU Reference Laboratory and other published sequences) including the ASFV Vietnam strain will be collected and used for primer and probe design to ensure high coverage over ASFVs. The MLV ASFV-ΔCD2vΔI177L and ASFV variants with CD2v/MGF360/MGF505 genes deleted independently or simultaneously which have been generated in our laboratory, and the wildtype ASFVs will be detected in this assay. Sequence alignment, primer and probe design, multiplex RT-PCR system optimizing will be performed as described in our previous publication.7. Validate the ASFV variants multiplex real-time PCR assay Specific research priorities include 1) validate the sensitivity: Ten-fold serial dilutions of ASFVs which were kept in our laboratory including ASFV BA71V (Genotype I), ASFV OURT88/1 and OURT88/3 (Genotype I), ASFV Vietnam (Genotype II), and ASFV Georgia 2007/1(Genotype II) will be made to achieve concentrations from 10^0to 10^5 HAD50/ml and to build the standard curves. The limits of detection will be determined from the lowest concentration that all replications are still generating positive signals; 2) validate the specificity: non-target swine viral isolates which are kept in our laboratory including BVDV, CSFV, PRRSV, PRV, Porcine Epidemic Diarrhea Virus will be used for diagnostic specificity test; 3) validate diagnostic performance on clinical samples: field clinical samples obtained from Task 1 will be used for clinical validation of the novel developed assay; 4) the OIE-recommended real-time PCR assay and commercially available ASFV DNA testing kits from Thermo Fisher Scientific (VetMAX™ African Swine Fever Virus Detection Kit), Indical Bioscience (virotype® ASFV PCR Kit) and IDEXX Laboratories (RealPCR ASFV DNA test) will be evaluated in parallel for comparison of their sensitivity and specificity.8.Statistical analysis and results communicationReproducibility analysis will be performed by calculating the mean value and coefficient of variation of replications of each test.The SigmaPlot software version 11.0 (Systat Software Inc., Chicago, USA) will be used to do the One-way analysis of variance (ANOVA) to determine the statistically significant differences, and will be used to analyze the specificity, sensitivity and degree of agreement. We will share and disseminate research results through publications and presentations in domestic/international meetings and veterinary journals.

Progress 03/01/23 to 02/29/24

Outputs
Target Audience:Researchers, regulators, animal health industries in the U.S. Changes/Problems: We established the mAb3007 based cELISA system. However, the performance of the cELISA system was not as good as we expected during validation with clinical samples (low sensitivity, can only detect theantibodies responses 28 days post vaccination/infection). Thus, we developed a sensitivep30 based ELISA system to replacethe cELISA system. The p30 based ELISA system can detect the specific antibodyresponses 14 days post vaccination/infection. Currently, we are working on validation (specificity) of the p30 based ELISA system with other common swine virus (CSFV, PRRSV, BVDV, PRV) infected serum samples. What opportunities for training and professional development has the project provided? This project provided training and professional development of IBC, IACUC, working in BSL-3 facilities, pig handling, pig bleeding, clinical sample collection from pigs, ELISA, cell culture, and molecular biological techniques for our technicians and students. How have the results been disseminated to communities of interest? We presented our results of using the p30 based ELISA and CD2v based ELISA system to test the antibody responses of ASF live attenuated vaccine immunized pigs in two international meetings: 1) 2023 NAPRRS/NC229: International Conference of Swine Viral Diseases; Chicago, IL; 11/30-12/02/ 2023; Oral presentation "Development of live-attenuated vaccine to protect pigs against the contemporary pandemic African swine fever virus"; 2) 2023 International African Swine Fever Workshop; Beijing, China; 09/17-09/20/2023; Oral presentation "Cellular and humoral immune responses of ASF live attenuated vaccine candidate: KNB-LAV1". What do you plan to do during the next reporting period to accomplish the goals?During the next reporting period, we plan to 1) Receive and put the clinical samples from pigs naturally infected with ASFVs into our long inventory system. 2) Validate the p30 based ELISA and CD2v based ELISA systems with more serum samples; 3) Optimize and validate multiplex real-time PCR assay for direct detection ASFV variants; 4) Share and disseminate research results through publications and presentations in domestic/international meetings and veterinary journals.

Impacts
What was accomplished under these goals? 1. Collect field clinical samples from pigs naturally infected with ASFV in commercial swine farms in Vietnam and the Philippines. • Obtained regulatory approvals for IBC and IACUC. • The reagents and materials for collecting field clinical samples have been sent to Vietnam and the Philippines. • Our collaborators have collected field clinical samples from pigs naturally infected with ASFV in local commercial swine farms. Challenges: ASF samples from Our collaborators (Vietnam and the Philippines) were delayed due to cross border transfer regulations. Clinical samples from pigs naturally infected with ASFVs was sent to Plum Island Animal Disease Center (New York) for testing in May, 2023. These samples are cleared for by USDA APHIS and are ready to be transferred to our laboratory at Kansas State University. Currently, we are waiting for the courier to transport the samples from Plum Island to Biosecurity Research Institute at Kansas State University, KS. 2. Collect field clinical samples from ASF-free pigs in local farms in the United States. • Obtained regulatory approvals for IBC and IACUC. • Collected 150 serum samples from 150 ASF-free pigs. • Collected 150 dry blood samples from 150 ASF-free pigs. • Collected 100 ear punch biopsy from 100 ASF-free pigs. 3. Transfer the collected clinical samples from Vietnam and the Philippines to the United States. ASF samples from Our collaborators (Vietnam and the Philippines) were delayed due to cross border transfer regulations. Clinical samples from pigs naturally infected with ASFVs was sent to Plum Island Animal Disease Center (New York) for testing in May, 2023. These samples are cleared for by USDA APHIS and are ready to be transferred to our laboratory at Kansas State University. Currently, we are waiting for the courier to transport the samples from Plum Island to Biosecurity Research Institute at Kansas State University, KS. 4. Develop, optimize and validate cELISA system using p30 protein as the capture antigen and mAb3007 as the competitive antibody. • Expressed and purified p30 protein with Baculovirus Expression System. • Cultured hybridomas which secreting mAb3007 and purified mAb3007 from the culture supernatant. • Horseradish peroxidase (HRP) labeled mAb3007. •Established the HRP-mAb3007 based cELISA system. However, the performance of HRP-mAb3007 based cELISA system was not as good as we expected (low sensitivity, can only detect theantibodies responses 28 days post vaccination/infection). Thus, we developed a sensitive p30 based ELISA to replacethe cELISA. The p30 based ELISA can detect the specific antibodyresponses 14 days post vaccination/infection. Currently, we are working on validation (specificity) of the p30 based normal ELISA with other common swine virus (CSFV, PRRSV, BVDV, PRV) infected serum samples. 5. Express CD2v protein, generate anti-CD2v mAbs, establish and validate the anti-CD2v mAb based cELISA system • Expressed and purified CD2v protein with Baculovirus Expression System. • Expressed and purified CD2v protein with Plant Expression System. • Immunized BALb/c mice with CD2v protein from both systems, and generated a panel of anti-CD2v mAbs (n=5). •Established the anti-CD2v mAb based cELISA system. 6. Develop, optimize and validate a reliable multiplex real-time PCR assay for ASFV variants testing. • Established sequence databases of I177L gene, CD2v gene and MGF gene which collected all available ASFV sequences from GenBank, ASFV sequences in our lab and other published sequences. • Completed sequence alignments, primer and probe design. • Prepared the standard template plasmids: pUC57-I177L, pUC57-CD2v and pUC57-MGF. • Orderedand received the commercially available multiplex reagents: iQ Multiplex Powermix from Bio-Rad; QIAGEN Multiplex PCR Kit from Qiagen; Platinum™ Multiplex PCR Master Mix from ThermoFisher, Multiplex PCR 5X Master Mix from New England Biolabs, andPath-ID Multiplex One-Step RTPCR Kit (Applied Biosystems/Life Technologies). Next step: Compare the performance of different multiplex reagents with designed primers and probes and optimize the ASFV variants multiplex real-time PCR system. Validate (diagnostic specificity and sensitivity) the ASFV variants multiplex real-time PCR system with clinical samples.

Publications

  • Type: Journal Articles Status: Published Year Published: 2023 Citation: Wang L., R. Madera, Y. Li, D.P. Gladue, M.V. Borca, M.T. McIntosh, J. Shi. 2023. Development of porcine monoclonal antibodies with in vitro neutralizing activity against Classical Swine Fever virus from C-Strain E2-specific single B cells. Viruses, 15(4):863.
  • Type: Journal Articles Status: Published Year Published: 2023 Citation: Truong Q.L., L. Wang, T.A. Nguyen, T.H. Nguyen, S.D. Tran, A.T. Vu, A.D. Le, V.G. Nguyen, P.T. Hoang, Y.T. Nguyen, T.L. Le, T.N. Van, T. Huynh, H. Lai, R. Madera, Y. Li, J. Shi, L.T. Nguyen. 2023. A cell-adapted live-attenuated vaccine candidate protects pigs against the homologous strain VNUA-ASFV-05L1, a representative strain of the contemporary pandemic African Swine Fever virus. Viruses, 15(10):2089.
  • Type: Journal Articles Status: Published Year Published: 2022 Citation: Wang L., S. Mi, R. Madera, Y. Li, W. Gong, C. Tu, J. Shi. 2022. A novel competitive ELISA for specifically measuring and differentiating immune responses to Classical Swine Fever C-strain vaccine in pigs. Viruses, 14:1544.


Progress 03/01/22 to 02/28/23

Outputs
Target Audience:Researchers, regulators and animal health industries. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project provided training and professional development of IBC, IACUC, working inBSL-3 facilities, pig handling, pig bleeding, clinical sample collection from pigs, ELISA, cell culture, and molecular biological techniques for our technicians andstudents. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?During the next reporting period, we plan to 1) Continue to work with our collaborators to collect and transfer clinical samples from foreign countries to U.S.; 2) establish and validate thecELISA systems; 3) establish and validate multiplex real-time PCR assay for direct detection ASFV variants;4)Share and disseminate research results throughpublications and presentations in domestic/international meetings and veterinary journals.

Impacts
What was accomplished under these goals? •Collect field clinical samples from pigs naturally infected with ASFV in commercial swine farms in Vietnam and the Philippines. 1) Obtained regulatory approvals for IBC and IACUC. 2) The reagents and materials for collecting field clinical samples have been sent to Vietnam and the Philippines. 3) Our collaborators have started to collect field clinical samples from pigs naturally infected with ASFV in local commercial swine farms. •Collect field clinical samples from ASF-free pigs in local farms in the United States. 1) Obtained regulatory approvals for IBC and IACUC. 2) Collected 150 serum samples from 150 ASF-free pigs. 3) Collected 150 dry blood samples from 150 ASF-free pigs. 4) Collected 100 ear punch biopsy from 100 ASF-free pigs. •Transfer the collected clinical samples from Vietnam and the Philippines to the United States. No data to report yet. •Develop, optimize and validate cELISA system using p30 protein as the capture antigen and mAb3007 as the competitive antibody. 1)Expressed and purified p30 protein with Baculovirus Expression System. 2) Cultured hybridomas which secreting mAb3007 and purified mAb3007 from the culture supernatant. 3) Horseradish peroxidase (HRP) labeled mAb3007. •Express CD2v protein with Baculovirus Expression System and generate anti-CD2v mAbs. 1) Expressed and purified CD2v protein with Baculovirus Expression System. 2) Expressed and purified CD2v protein with Plant Expression System. 3) Immunized BALb/c mice with CD2v protein from both systems to generate anti-CD2v mAbs. •Develop, optimize and validate cELISA system using CD2v protein as the capture antigen and anti-CD2v mAb as the competitive antibody. 1) Established CD2v based ELISA system to test anti-CD2v antibodies in pig serum.This CD2v based ELISA system can test the antibodies in pig serum 21 days post of immunization with subunit vaccine.Currently, working on validate the CD2v based ELISA system with more serum samples. • Develop, optimize and validate a reliable multiplex real-time PCR assay for ASFV variants testing. 1) Established sequence databases of I177L gene, CD2v gene and MGF gene which includeall available ASFV sequences from GenBank, ASFV sequences in our lab and other published sequences.Currently working on sequence alignment, primer and probe design.

Publications