Periodic Reporting for period 1 - REPRODIVAC (Next-generation vaccines and diagnostics to prevent livestock reproductive diseases of worldwide impact)
Reporting period: 2022-09-01 to 2024-02-29
Endemic and zoonotic infectious reproductive diseases of livestock cause major economic losses globally and threaten food security and public health. In the pig industry, for instance, annual losses due to porcine reproductive and respiratory syndrome virus (PRRSV) in the USA and Europe alone are estimated to exceed $600 million and €1.5 billion, respectively. REPRODIVAC is developing new and improved vaccines and diagnostic tools required to better control four priority abortifacient diseases: porcine reproductive and respiratory syndrome (caused by PRRSV), Q fever (caused by Coxiella burnetii), ovine enzootic abortion (OEA) (caused by Chlamydia abortus), and porcine brucellosis (caused by Brucella suis). The consortium spans academia and industry with expertise in structural and molecular biology, microbiology, immunology, plant and veterinary sciences, diagnostic test and vaccine development. This enables an interdisciplinary approach to address the target reproductive disorders by: (1) applying reverse and structural vaccinology to select and design vaccine and diagnostic candidate antigens; (2) exploiting relevant protein expression systems for the production of these antigens; (3) producing rationally attenuated and viral vectored vaccines; (4) utilising established animal models for the rational evaluation of candidate vaccines; and (5) developing a suite of molecular and immunological diagnostic tests, including point-of-care tests (PoC) to discriminate vaccinated from infected animals (DIVA). We will develop a broadly protective PRRSV vaccine, and a serological ELISA that will reliably correlate with PRRSV neutralising antibody titres. We will identify protective subunit vaccine candidates for Q fever and validate a companion serological DIVA test. We will further refine an OEA vaccine for commercialisation and pursue a complementary approach towards a DIVA-compatible next-generation subunit vaccine and serological and molecular DIVA/PoC tests. We will develop live attenuated B. suis vaccines and brucellosis diagnostic tests with improved specificity.
The first 18 months of scientific activities have largely focussed on the definition and design of vaccine and diagnostic assay on the basis of (i) the type of immune response conferring protection against the pathogen, (ii) the knowledge of pathogen components (antigens) against which protective and non-protective immune responses are directed and (iii) the structural features of these components:
• First steps have been accomplished towards the identification of PRRSV antigens targeted by virus neutralising immune responses. Pigs were identified with antibodies capable of broadly neutralising PRRSV. A panel of recombinant PRRSV glycoproteins has been constructed to isolate broadly neutralising monoclonal antibodies. To help define virus structures targeted by these antibodies, a high-resolution model of the PRRSV virion by cryo-electron microscopy is being constructed. Recombinant pseudorabies virus vectors expressing PRRSV glycoprotein sequences have been constructed and characterised in vitro.
• Live attenuated vaccine strains of B. suis have been designed and produced by the targeted mutation of genes and antigens have been identified for development of diagnostic assays.
• A protocol has been optimised for the preparation of an antigen formulation based on C. abortus outer membrane protein complex for exploitation by one of the industrial partners.
• Diversified bioinformatics approaches have been adopted to identify candidate antigens for the development of C. abortus and C. burnetii DIVA subunit vaccines and companion DIVA diagnostic assays. Some of the identified antigens have been produced in recombinant form by “traditional” expression systems (i.e. Escherichia coli) or in association with “immunopotentiating” moieties using an “unconventional” expression system (i.e. Nicotiana benthamiana plants) and the scale up is underway to allow in vitro/in vivo testing.
• Polyclonal antibodies have been generated to candidate C. burnetii antigens and an in vitro infection assay developed to test their neutralising capacity.
• A validated workflow for antigen testing has been developed using a candidate C. burnetii antigen as test compound.
• First steps have been accomplished towards the identification of PRRSV antigens targeted by virus neutralising immune responses. Pigs were identified with antibodies capable of broadly neutralising PRRSV. A panel of recombinant PRRSV glycoproteins has been constructed to isolate broadly neutralising monoclonal antibodies. To help define virus structures targeted by these antibodies, a high-resolution model of the PRRSV virion by cryo-electron microscopy is being constructed. Recombinant pseudorabies virus vectors expressing PRRSV glycoprotein sequences have been constructed and characterised in vitro.
• Live attenuated vaccine strains of B. suis have been designed and produced by the targeted mutation of genes and antigens have been identified for development of diagnostic assays.
• A protocol has been optimised for the preparation of an antigen formulation based on C. abortus outer membrane protein complex for exploitation by one of the industrial partners.
• Diversified bioinformatics approaches have been adopted to identify candidate antigens for the development of C. abortus and C. burnetii DIVA subunit vaccines and companion DIVA diagnostic assays. Some of the identified antigens have been produced in recombinant form by “traditional” expression systems (i.e. Escherichia coli) or in association with “immunopotentiating” moieties using an “unconventional” expression system (i.e. Nicotiana benthamiana plants) and the scale up is underway to allow in vitro/in vivo testing.
• Polyclonal antibodies have been generated to candidate C. burnetii antigens and an in vitro infection assay developed to test their neutralising capacity.
• A validated workflow for antigen testing has been developed using a candidate C. burnetii antigen as test compound.
The REPRODIVAC project envisaged vaccines and diagnostics may have the potential to:
• Increase the availability of veterinary medicinal products for animal species (e.g. sheep and goats) traditionally overlooked by pharmaceutical companies due to the small market size.
• Progress the implementation of preventive veterinary medicine programs by improving external and internal biosecurity in farms by: (i) correctly identifying infected animals to avoid transmission to naïve ones; (ii) protecting animals with efficacious vaccines to decrease the probability of becoming sick/dying and transmitting the pathogen; (iii) correctly treating infected animals with suitable medicinal products.
• Improve animal welfare by decreasing the prevalence of the selected diseases at a population level (better control of the disease) and decrease the clinical symptoms by the protection conferred by the vaccines.
• Positively impact human health by reducing and preventing the circulation of the zoonotic pathogens C. abortus, C. burnetii and B. suis, all of which can affect humans and their foetuses to different levels of severity.
• Increase the availability of veterinary medicinal products for animal species (e.g. sheep and goats) traditionally overlooked by pharmaceutical companies due to the small market size.
• Progress the implementation of preventive veterinary medicine programs by improving external and internal biosecurity in farms by: (i) correctly identifying infected animals to avoid transmission to naïve ones; (ii) protecting animals with efficacious vaccines to decrease the probability of becoming sick/dying and transmitting the pathogen; (iii) correctly treating infected animals with suitable medicinal products.
• Improve animal welfare by decreasing the prevalence of the selected diseases at a population level (better control of the disease) and decrease the clinical symptoms by the protection conferred by the vaccines.
• Positively impact human health by reducing and preventing the circulation of the zoonotic pathogens C. abortus, C. burnetii and B. suis, all of which can affect humans and their foetuses to different levels of severity.