Genetic and biological characteristics of the globally circulating H5N8 avian influenza viruses and the protective efficacy offered by the poultry vaccine currently used in China

The H5N8 avian influenza viruses have been widely circulating in wild birds and are responsible for the loss of over 33 million domestic poultry in Europe, Russia, Middle East, and Asia since January 2020. To monitor the invasion and spread of the H5N8 virus in China, we performed active surveillance by analyzing 317 wild bird samples and swab samples collected from 41,172 poultry all over the country. We isolated 22 H5N8 viruses from wild birds and 14 H5N8 viruses from waterfowls. Genetic analysis indicated that the 36 viruses formed two different genotypes: one genotype viruses were widely detected from different wild birds and domestic waterfowls; the other genotype was isolated from a whopper swan. We further revealed the origin and spatiotemporal spread of these two distinct H5N8 virus genotypes in 2020 and 2021. Animal studies indicated that the H5N8 isolates are highly pathogenic to chickens, mildly pathogenic in ducks, but have distinct pathotypes in mice. Moreover, we found that vaccinated poultry in China could be completely protected against H5N8 virus challenge. Given that the H5N8 viruses are likely to continue to spread in wild birds, vaccination of poultry is highly recommended in high-risk countries to prevent H5N8 avian influenza.

Encapsulation of Cochleates Derived from Salmonella Infantis with Biopolymers to Develop a Potential Oral Poultry Vaccine

The aim of this study was to develop and characterize Salmonellaenterica serovar Infantis (S. Infantis) cochleates protected by encapsulation technology as a potential vaccine and to determine its safety in pullets. Cochleates were encapsulated by two technologies, spray drying and ionotropic gelation at different concentrations (0–15% v/v), and were characterized by physicochemical properties, protein content and Fourier Transform Infrared Spectroscopy (FTIR). The cochleates were white liquid suspensions with tubular shapes and a protein content of 1.0–2.1 mg/mL. After encapsulation by spray drying, microparticles ranged in size from 10.4–16.9 µm, were spherical in shape, and the protein content was 0.7–1.8 mg/g. After encapsulation by ionotropic gelation, beads ranged in size from 1620–1950 µm and were spherical in shape with a protein content of 1.0–2.5 mg/g. FTIR analysis indicated that both encapsulation processes were efficient. The cochleates encapsulated by ionotropic gelation were then tested for safety in pullets. No ill effect on the health of animals was observed upon physical or postmortem examination. In conclusion, this study was the first step in developing a potential oral S. Infantis vaccine safe for poultry using a novel cochleate encapsulation technology. Future studies are needed to determine the effectiveness of the vaccine.

Multivalent poultry vaccine development using Protein Glycan Coupling Technology

Background Poultry is the world's most popular animal-based food and global production has tripled in the past 20 years alone. Low-cost vaccines that can be combined to protect poultry against multiple infections are a current global imperative. Glycoconjugate vaccines, which consist of an immunogenic protein covalently coupled to glycan antigens of the targeted pathogen, have a proven track record in human vaccinology, but have yet to be used for livestock due to prohibitively high manufacturing costs. To overcome this, we use Protein Glycan Coupling Technology (PGCT), which enables the production of glycoconjugates in bacterial cells at considerably reduced costs, to generate a candidate glycan-based live vaccine intended to simultaneously protect against Campylobacter jejuni, avian pathogenic Escherichia coli (APEC) and Clostridium perfringens. Campylobacter is the most common cause of food poisoning, whereas colibacillosis and necrotic enteritis are widespread and devastating infectious diseases in poultry. Results We demonstrate the functional transfer of C. jejuni protein glycosylation (pgl) locus into the genome of APEC χ7122 serotype O78:H9. The integration caused mild attenuation of the χ7122 strain following oral inoculation of chickens without impairing its ability to colonise the respiratory tract. We exploit the χ7122 pgl integrant as bacterial vectors delivering a glycoprotein decorated with the C. jejuni heptasaccharide glycan antigen. To this end we engineered χ7122 pgl to express glycosylated NetB toxoid from C. perfringens and tested its ability to reduce caecal colonisation of chickens by C. jejuni and protect against intra-air sac challenge with the homologous APEC strain. Conclusions We generated a candidate glycan-based multivalent live vaccine with the potential to induce protection against key avian and zoonotic pathogens (C. jejuni, APEC, C. perfringens). The live vaccine failed to significantly reduce Campylobacter colonisation under the conditions tested but was protective against homologous APEC challenge. Nevertheless, we present a strategy towards the production of low-cost “live-attenuated multivalent vaccine factories” with the ability to express glycoconjugates in poultry.

Proteomic analysis of chicken bone marrow-derived dendritic cells in response to an inactivated IBV + NDV poultry vaccine

Inactivated poultry vaccines are subject to routine potency testing for batch release, requiring large numbers of animals. The replacement of in vivo tests for cell-based alternatives can be facilitated by the identification of biomarkers for vaccine-induced immune responses. In this study, chicken bone marrow-derived dendritic cells were stimulated with an inactivated vaccine for infectious bronchitis virus and Newcastle disease virus, as well as inactivated infectious bronchitis virus only, and lipopolysaccharides as positive control, or left unstimulated for comparison with the stimulated samples. Next, the cells were lysed and subjected to proteomic analysis. Stimulation with the vaccine resulted in 66 differentially expressed proteins associated with mRNA translation, immune responses, lipid metabolism and the proteasome. For the eight most significantly upregulated proteins, mRNA expression levels were assessed. Markers that showed increased expression at both mRNA and protein levels included PLIN2 and PSMB1. Stimulation with infectious bronchitis virus only resulted in 25 differentially expressed proteins, which were mostly proteins containing Src homology 2 domains. Stimulation with lipopolysaccharides resulted in 118 differentially expressed proteins associated with dendritic cell maturation and antimicrobial activity. This study provides leads to a better understanding of the activation of dendritic cells by an inactivated poultry vaccine, and identified PLIN2 and PSMB1 as potential biomarkers for cell-based potency testing.

Review of Poultry Production and Poultry Vaccine Manufacture in Nepal

Poultry industry is one of the strong pillars of Nepal’s agricultural production system, contributing around 4% in the national gross domestic product (GDP). Nepal is self-reliant in poultry meat and egg production. This sector provides employment to thousands of people and has become a major source of income to rural people. Low investment cost, less manpower requirement, and quick returns attract many investors towards poultry farming and hence the population and productivity of poultry is increasing year after year. Different viral, bacterial, protozoal and fungal diseases, including influenza, fowl typhoid, coccidiosis and mycotoxicosis, cause tremendous economic loss to the poultry sector of Nepal each year. Vaccines can be an effective preventive measure against poultry diseases and Nepal government together with the private sectors produce vaccines against different poultry diseases. Still, poultry vaccine production within the country is not enough and depends on imports from other countries. Considering the continuous growth in the poultry production and constant threat of disease outbreaks, government of Nepal as well as private sectors should invest more on vaccine production within the country. This article explains the current status of poultry production and vaccine development in Nepal.

Genetic and biological properties of H7N9 avian influenza viruses detected after application of the H7N9 poultry vaccine in China

The H7N9 avian influenza virus (AIV) that emerged in China have caused five waves of human infection. Further human cases have been successfully prevented since September 2017 through the use of an H7N9 vaccine in poultry. However, the H7N9 AIV has not been eradicated from poultry in China, and its evolution remains largely unexplored. In this study, we isolated 19 H7N9 AIVs during surveillance and diagnosis from February 2018 to December 2019, and genetic analysis showed that these viruses have formed two different genotypes. Animal studies indicated that the H7N9 viruses are highly lethal to chicken, cause mild infection in ducks, but have distinct pathotypes in mice. The viruses bound to avian-type receptors with high affinity, but gradually lost their ability to bind to human-type receptors. Importantly, we found that H7N9 AIVs isolated in 2019 were antigenically different from the H7N9 vaccine strain that was used for H7N9 influenza control in poultry, and that replication of these viruses cannot, therefore, be completely prevented in vaccinated chickens. We further revealed that two amino acid mutations at positions 135 and 160 in the HA protein added two glycosylation sites and facilitated the escape of the H7N9 viruses from the vaccine-induced immunity. Our study provides important insights into H7N9 virus evolution and control.

Quality assessment of commercially available Newcastle disease vaccine in Lagos State, Nigeria

Newcastle disease (ND) outbreaks occur among vaccinated and non-vaccinated poultry flocks causing varying degrees of economic losses despite vigorous vaccination for the control of the disease. In this study, the qualities of vaccines available for the control of ND in poultry in Lagos State were evaluated. A total of 264 blood samples were collected from poultry flocks of the enrolled farmers and 80vials of ND vaccines were obtained from nine poultry vaccine retailers patronized by the enrolled farmers. Twenty-five vials of ND vaccines were also collected from five importers that were patronized by the poultry vaccine retailers. Five vials each of the different ND vaccines were purchased from each retailers or importers and were used as representative samples of the different ND vaccines available for sale at the time of sampling. These were subjected to both physical and serological testing using Haemagglutination test (HA), Haemagglutination–inhibition test (HI) and Enzyme?linked immunosorbent assay (ELISA). Coefficient of variance of solubility among all the vaccines ranged from 7.06% to 378.89%. Vaccines obtained from retailers had meanHA titres of between 0.2 log and 11 log , while for the imported vaccines the mean HA titre 2 2 was between 6 log₂and 10.8log₂. Two hundred and sixty-four sera were tested for ND antibody, out of which 240 (90.91%) and 262 (99.24%) were positive for the presence of protective HI and ELISA ND antibodies respectively. From this study, lower coefficient of variance of solubility was observed in vaccines from importers than those from retailerswhich could indicate that vaccines are probably better stored by importers than the retailers. There should be proactive government monitoring agency at all levels of vaccine protocols.

Characterization of Newcastle Disease Virus in Southeast Asia and East Asia: Fusion Protein Gene

The aim of this study was to generate the bioinformatics analysis of the circulating NDVs in Southeast Asia, East Asia, and the vaccine virus strains through a database of isolates stored in GenBank® (National Center for Biotechnology Information, USA). The used isolates were AJ629062.1 (La Sota), AF309418.1 (B1), EF201805.1 (Mukteswar), KT445901.1 (Komarov), JX524203.1 (V4), AY935499.2 (I-2), KC987036.1 (F), KF767104.1 (Indonesia), KF767105.1 (Indonesia), KF767106.1 (Indonesia), HQ697255.1 (Indonesia), HQ697256.1 (Indonesia), HQ697261.1 (Indonesia), JX012096.2 (Malaysia), GU332646.1 (Vietnam), AF358786.1 (Taiwan), AF358788.1 (China), KT380032.1 (Republic of Korea), and KC503416.1 (Japan). As the results, this study have revealed the data of homology, pathotype, genetic distance, B cell epitope prediction, and molecular phylogenetic analysis of circulating NDVs in Southeast Asia and East Asia and vaccine virus strains. Thus, the results of this study can be used as a reference for vaccine design studies in the applications of poultry vaccine industryReceived: 28 August 2019; Accepted: 31 December 2019; Published: 11 January 2020.

Nearly Complete Genome Sequence of a Serotype 1 Fowl Adenovirus Strain Isolated in Jiangsu, China

Here, we report the nearly complete genome sequence of nonpathogenic serotype 1 fowl adenovirus (FAdV) strain JS2017, which was isolated in Jiangsu Province of China. The JS2017 genome is 43,681 bp long. We propose that this virus could serve as a viral vector for future poultry vaccine research.