A Novel Recombinant Newcastle Disease Virus Vectored DIVA Vaccine against Peste des Petits Ruminants in Goats

Immune response after oral immunization of goats and foxes with an NDV vectored rabies vaccine candidate

Vaccination of the reservoir species is a key component in the global fight against rabies. For wildlife reservoir species and hard to reach spillover species (e. g. ruminant farm animals), oral vaccination is the only solution. In search for a novel potent and safe oral rabies vaccine, we generated a recombinant vector virus based on lentogenic Newcastle disease virus (NDV) strain Clone 30 that expresses the glycoprotein G of rabies virus (RABV) vaccine strain SAD L16 (rNDV_GRABV). Transgene expression and virus replication was verified in avian and mammalian cells. To test immunogenicity and viral shedding, in a proof-of-concept study six goats and foxes, representing herbivore and carnivore species susceptible to rabies, each received a single dose of rNDV_GRABV (108.5 TCID50/animal) by direct oral application. For comparison, three animals received the similar dose of the empty viral vector (rNDV). All animals remained clinically inconspicuous during the trial. Viral RNA could be isolated from oral and nasal swabs until four (goats) or seven days (foxes) post vaccination, while infectious NDV could not be re-isolated. After four weeks, three out of six rNDV_GRABV vaccinated foxes developed RABV binding and virus neutralizing antibodies. Five out of six rNDV_GRABV vaccinated goats displayed RABV G specific antibodies either detected by ELISA or RFFIT. Additionally, NDV and RABV specific T cell activity was demonstrated in some of the vaccinated animals by detecting antigen specific interferon γ secretion in lymphocytes isolated from pharyngeal lymph nodes. In conclusion, the NDV vectored rabies vaccine rNDV_GRABV was safe and immunogenic after a single oral application in goats and foxes, and highlight the potential of NDV as vector for oral vaccines in mammals.

Negative-Strand RNA Virus-Vectored Vaccines

Vectored RNA vaccines offer a variety of possibilities to engineer targeted vaccines. They are cost-effective and safe, but replication competent, activating the humoral as well as the cellular immune system.This chapter focuses on RNA vaccines derived from negative-strand RNA viruses from the order Mononegavirales with special attention to Newcastle disease virus-based vaccines and their generation. It shall provide an overview on the advantages and disadvantages of certain vector platforms as well as their scopes of application, including an additional section on experimental COVID-19 vaccines.

Construction of Recombinant Rabies Virus Vectors Expressing H or F Protein of Peste des Petits Ruminants Virus

Simple Summary

Peste des petits ruminants (PPR) is one of the most contagious and fatal diseases of small ruminants. In this study, two recombinant viruses rSRV9-H and rSRV9-F, which express the envelope glycoprotein H (hemagglutinin protein) or F (fusion protein) protein, respectively, were successfully generated with a rabies virus as vector. The constructed viruses had good proliferative activity and stability and provided potential bivalent inactivated vaccine candidate strains for the prevention of PPR and livestock rabies.

Abstract

Peste des petits ruminants (PPR) is one of the most contagious and fatal diseases of small ruminants in the world and is classified as a category A epidemic disease. It is the target of a global eradication campaign led by the Office International des Epizooties (OIE) and Food and Agriculture Organization of the United Nations (FAO). The PPR live attenuated vaccine is currently the most widely used and approved vaccine, but the use of this vaccine interferes with the serological testing of the PPR elimination program, and there is a potential safety risk. Viral vector vaccines are one of the most promising methods to solve this dilemma. In this study, the full-length infectious clone plasmid of rabies virus (RABV), pD-SRV9-PM-LASV, was used as the backbone, and the envelope glycoprotein H (hemagglutinin protein) or F (fusion protein) gene of PPRV was inserted into the backbone plasmid to construct the infectious clones pD-SRV9-PM-PPRV-H and pD-SRV9-PM-PPRV-F, which express the PPRV H and PPRV F genes, respectively. The correct construction of these infectious clones was verified after sequencing and double digestion. The infectious clones were transfected with a helper plasmid into BSR/T7 cells, and recombinant viruses were successfully rescued by direct immunofluorescence, indirect immunofluorescence, Western blotting, and transmission electron microscopy and named rSRV9-H and rSRV9-F. The results of growth kinetics studies indicated that the inserted gene did not affect virus proliferation. Stability studies revealed that the inserted target gene was stably expressed in recombinant RABV for at least 15 generations. In this study, the recombinant viruses rSRV9-H and rSRV9-F were successfully rescued. The constructed viruses had good proliferative activity and stability and provided potential bivalent inactivated vaccine candidate strains for the prevention of PPR and livestock rabies.

Development and Scalable Production of Newcastle Disease Virus-Vectored Vaccines for Human and Veterinary Use

The COVID-19 pandemic has highlighted the need for efficient vaccine platforms that can rapidly be developed and manufactured on a large scale to immunize the population against emerging viruses. Viral-vectored vaccines are prominent vaccine platforms that have been approved for use against the Ebola virus and SARS-CoV-2. The Newcastle Disease Virus is a promising viral vector, as an avian paramyxovirus that infects poultry but is safe for use in humans and other animals. NDV has been extensively studied not only as an oncolytic virus but also a vector for human and veterinary vaccines, with currently ongoing clinical trials for use against SARS-CoV-2. However, there is a gap in NDV research when it comes to process development and scalable manufacturing, which are critical for future approved vaccines. In this review, we summarize the advantages of NDV as a viral vector, describe the steps and limitations to generating recombinant NDV constructs, review the advances in human and veterinary vaccine candidates in pre-clinical and clinical tests, and elaborate on production in embryonated chicken eggs and cell culture. Mainly, we discuss the existing data on NDV propagation from a process development perspective and provide prospects for the next steps necessary to potentially achieve large-scale NDV-vectored vaccine manufacturing.

Thermostable Vaccines in Veterinary Medicine: State of the Art and Opportunities to Be Seized

The COVID-19 pandemic has highlighted the weakness of the vaccine supply chain, and the lack of thermostable formulations is one of its major limitations. This study presents evidence from peer-reviewed literature on the development of thermostable vaccines for veterinary use. A systematic review and meta-analysis were performed to evaluate the immunogenicity and/or the efficacy/effectiveness of thermostable vaccines against infectious diseases. The selected studies (n = 78) assessed the vaccine’s heat stability under different temperature conditions and over different periods. Only one study assessed the exposure of the vaccine to freezing temperatures. Two field studies provided robust evidence on the immunogenicity of commercial vaccines stored at temperatures far in excess of the manufacturer’s recommended cold-chain conditions. The drying process was the most-used method to improve the vaccine’s thermostability, along with the use of different stabilizers. The pooled vaccine efficacy was estimated to be high (VE = 69%), highlighting the importance of vaccination in reducing the economic losses due to the disease impact. These findings provide evidence on the needs and benefits of developing a portfolio of heat- and freeze-stable veterinary vaccines to unleash the true potential of immunization as an essential component of improved animal health and welfare, reduce the burden of certain zoonotic events and thus contribute to economic resilience worldwide.

Immunization With Bovine Herpesvirus-4-Based Vector Delivering PPRV-H Protein Protects Sheep From PPRV Challenge

The Morbillivirus peste des petits ruminants virus (PPRV) is the causal agent of a highly contagious disease that mostly affects sheep and goats and produces considerable losses in developing countries. Current PPRV control strategies rely on live-attenuated vaccines, which are not ideal, as they cannot differentiate infected from vaccinated animals (DIVA). Recombinant vector-based vaccines expressing viral subunits can provide an alternative to conventional vaccines, as they can be easily paired with DIVA diagnostic tools. In the present work, we used the bovine herpesvirus-4-based vector (BoHV-4-A) to deliver PPRV hemagglutinin H antigen (BoHV-4-A-PPRV-H-ΔTK). Vaccination with BoHV-4-A-PPRV-H-ΔTK protected sheep from virulent PPRV challenge and prevented virus shedding. Protection correlated with anti-PPRV IgGs, neutralizing antibodies and IFN-γ-producing cells induced by the vaccine. Detection of antibodies exclusively against H-PPRV in animal sera and not against other PPRV viral proteins such as F or N could serve as a DIVA diagnostic test when using BoHV-4-A-PPRV-H-ΔTK as vaccine. Our data indicate that BoHV-4-A-PPRV-H-ΔTK could be a promising new approach for PPRV eradication programs.

A New Look at Vaccine Strategies Against PPRV Focused on Adenoviral Candidates

Peste des petits ruminants virus (PPRV) is a virus that mainly infects goats and sheep causing significant economic loss in Africa and Asia, but also posing a serious threat to Europe, as recent outbreaks in Georgia (2016) and Bulgaria (2018) have been reported. In order to carry out the eradication of PPRV, an objective set for 2030 by the Office International des Epizooties (OIE) and the Food and Agriculture Organization of the United Nations (FAO), close collaboration between governments, pharmaceutical companies, farmers and researchers, among others, is needed. Today, more than ever, as seen in the response to the SARS-CoV2 pandemic that we are currently experiencing, these goals are feasible. We summarize in this review the current vaccination approaches against PPRV in the field, discussing their advantages and shortfalls, as well as the development and generation of new vaccination strategies, focusing on the potential use of adenovirus as vaccine platform against PPRV and more broadly against other ruminant pathogens.

Long term immunity against Peste Des Petits Ruminants mediated by a recombinant Newcastle disease virus vaccine

Peste des Petits Ruminants (PPR) is a highly contagious and often fatal disease of sheep and goats. Conventional live vaccines have been successfully used in endemic countries however, there are not completely safe and not allowing differentiation between vaccinated and infected animals (DIVA). In this study, a recombinant Newcastle disease virus (NDV) expressing the hemagglutinin of PPRV (NDV-PPRVH) was evaluated on small ruminants by serology response in sheep and goats, experimental infection in goats and immunity duration in sheep. The NDV-PPRVH vaccine injected twice at 28 days' interval, provided full protection against challenge with a virulent PPR strain in the most sensitive species and induced significant neutralizing antibodies. Immunological response in goats was slightly higher than sheep and the vaccine injected at 10^8.0 50 % egg infective dose/mL allowed anti-PPRV antibodies that lasted at least 12 months as shown by antibody response monitoring in sheep. The NDV vector presented a limited replication in the host and vaccinated animals remained negative when tested by cELISA based on PPRV nucleoprotein allowing DIVA. This recombinant vaccine appears to be a promising candidate in a free at risk countries and may be an important component of the global strategy for PPR eradication.

The next-generation coronavirus diagnostic techniques with particular emphasis on the SARS-CoV-2

The potential zoonotic coronaviruses (SARS-CoV, MERS-CoV, and SARS-CoV-2) are of global health concerns. Early diagnosis is the milestone in their mitigation, control, and eradication. Many diagnostic techniques are showing great success and have many advantages, such as the rapid turnover of the results, high accuracy, and high specificity and sensitivity. However, some of these techniques have several pitfalls if samples were not collected, processed, and transported in the standard ways and if these techniques were not practiced with extreme caution and precision. This may lead to false-negative/positive results. This may affect the downstream management of the affected cases. These techniques require regular fine-tuning, upgrading, and optimization. The continuous evolution of new strains and viruses belong to the coronaviruses is hampering the success of many classical techniques. There are urgent needs for next generations of coronaviruses diagnostic assays that overcome these pitfalls. This new generation of diagnostic tests should be able to do simultaneous, multiplex, and high-throughput detection of various coronavirus in one reaction. Furthermore, the development of novel assays and techniques that enable the in situ detection of the virus on the environmental samples, especially air, water, and surfaces, should be given considerable attention in the future. These approaches will have a substantial positive impact on the mitigation and eradication of coronaviruses, including the current SARS-CoV-2 pandemic.

Progress towards Eradication of Peste des Petits Ruminants through Vaccination

Peste des petits ruminants (PPR) is a transboundary viral disease that threatens more than 1.74 billion goats and sheep in approximately 70 countries globally. In 2015, the international community set the goal of eradicating PPR by 2030, and, since then, Food and Agriculture Organization of the United Nations (FAO) and World Organization for Animal Health (OIE) have jointly developed and implemented the Global Control and Eradication Strategy for PPR. Here, data from the United Nations Food and Agriculture Organization Statistical Database (FAOSTAT), the OIE World Animal Health Information System (WAHIS), Regional Roadmap Meetings, and countries' responses to PPR Monitoring and Assessment Tool (PMAT) questionnaires were analyzed to inform on current progress towards PPR eradication. OIE recorded the use of over 333 million doses of vaccine in 12 countries from 2015 to 2018, 41.8% of which were used in Asia and 58.2% in Africa. Between 2015 and 2019, a total of 12,757 PPR outbreaks were reported to OIE: 75.1% in Asia, 24.8% in Africa, and 0.1% in Europe. The number of global outbreaks in 2019 fell to 1218, compared with 3688 in 2015. Analysis of vaccine use and PPR outbreaks in countries indicates that disease control strategies, particularly vaccination campaigns and vaccine distribution strategies, still require scientific evaluation. It is imperative that vaccination is undertaken based on the epidemiology of the disease in a region and is coordinated between neighboring countries to restrict transboundary movements. Strengthening surveillance and post-vaccination sero-monitoring at the national level is also essential. The PPR vaccine stock/bank established by FAO, OIE, and other partners have improved the quality assurance and supply of vaccines. However, to achieve PPR eradication, filling the funding gap for vaccination campaigns and other program activities will be critical.

Recombinant Technologies to Improve Ruminant Production Systems: The Past, Present and Future

The use of recombinant technologies has been proposed as an alternative to improve livestock production systems for more than 25 years. However, its effects on animal health and performance have not been described. Thus, understanding the use of recombinant technology could help to improve public acceptance. The objective of this review is to describe the effects of recombinant technologies and proteins on the performance, health status, and rumen fermentation of meat and milk ruminants. The heterologous expression and purification of proteins mainly include eukaryotic and prokaryotic systems like Escherichia coli and Pichia pastoris. Recombinant hormones have been commercially available since 1992, their effects remarkably improving both the reproductive and productive performance of animals. More recently the use of recombinant antigens and immune cells have proven to be effective in increasing meat and milk production in ruminant production systems. Likewise, the use of recombinant vaccines could help to reduce drug resistance developed by parasites and improve animal health. Recombinant enzymes and probiotics could help to enhance rumen fermentation and animal efficiency. Likewise, the use of recombinant technologies has been extended to the food industry as a strategy to enhance the organoleptic properties of animal-food sources, reduce food waste and mitigate the environmental impact. Despite these promising results, many of these recombinant technologies are still highly experimental. Thus, the feasibility of these technologies should be carefully addressed before implementation. Alternatively, the use of transgenic animals and the development of genome editing technology has expanded the frontiers in science and research. However, their use and implementation depend on complex policies and regulations that are still under development.