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Fulltext Vaccines and vaccination against infectious bursal disease of chickens: prospects and challenges

Liew, Pit Sze, Nurulfiza Mat Isa, Omar Abdul Rahman, Aini Ideris, Mohd HAIRBEJO

The Pertanika Journal of Scholarly Research Reviews, 2016;2(2):23-39.
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Infectious bursal disease (IBD), also known as the Gumboro disease, has been a great
concern for poultry industry worldwide. The first outbreak of IBD due to very virulent (vv) IBD virus
(IBDV) infection in Malaysia was reported in 1991. The major economic impact of the disease is high
mortality and poor performance. The virus causes immunosuppression where if the infected chicken
recovered from the acute disease, they become more susceptible to infections of other pathogens and
fail to respond to vaccines. Therefore, prevention is important and vaccination has become the
principal control measure of IBDV infection in chickens. The conventional attenuated live and killed
vaccines are the most commonly used vaccines. With the advancement of knowledge and technology,
new generation of genetically-engineered vaccines like viral vector and immune complex vaccines
have been commercialised. Moreover, hatchery vaccination is becoming a common practise, in
addition to farm vaccination. Currently, the disease is considerably under controlled with the
introduction of vaccination. However, occasional field outbreaks are still commonly reported. The
demand for vaccines that could suit the field situation continues to exist. The endemicity of disease,
presence of challenge in the farm and maternally derived antibody in chicks are affecting the choice
vaccine as well as the vaccine development and vaccination strategies. In this review, advances made
in various vaccines that have been commercialised or under development, and challenges that they
face, are outlined. Furthermore, how the emergence of vvIBDV affect the progress of vaccine
development and influence its vaccination strategy are discussed.
Fulltext Farming of Plant-Based Veterinary Vaccines and Their Applications for Disease Prevention in Animals

Liew PS, Hair-Bejo M

Adv Virol, 2015;2015:936940.
PMID: 26351454 DOI: 10.1155/2015/936940

Plants have been studied for the production of pharmaceutical compounds for more than two decades now. Ever since the plant-made poultry vaccine against Newcastle disease virus made a breakthrough and went all the way to obtain regulatory approval, research to use plants for expression and delivery of vaccine proteins for animals was intensified. Indeed, in view of the high production costs of veterinary vaccines, plants represent attractive biofactories and offer many promising advantages in the production of recombinant vaccine proteins. Furthermore, the possibility of conducting immunogenicity and challenge studies in target animals has greatly exaggerated the progress. Although there are no edible plant-produced animal vaccines in the market, plant-based vaccine technology has great potentials. In this review, development, uses, and advantages of plant-based recombinant protein production in various expression platforms are discussed. In addition, examples of plant-based veterinary vaccines showing strong indication in terms of efficacy in animal disease prevention are also described.
Fulltext Pathogenicity of Salmonella enterica subspecies enterica serovar Enteritidis phage type 1 in one-day-old specific pathogen-free chicks

Ahmad S, Hair-Bejo M, Hussein EA, Awad EA, Saeed MI, Liew PS, et al.

Open Vet J, 2022;12(6):839-850.
PMID: 36650863 DOI: 10.5455/OVJ.2022.v12.i6.8

BACKGROUND: The studies about Salmonella infection in newly hatched chicks were not extensive.
AIM: The objective of this study was to determine the pathogenicity of Salmonella enterica subspecies enterica serovar Enteritidis (SE) phage type (PT) 1 in one-day-old specific pathogen-free (SPF) chicks.
METHODS: Seventy, one-day-old SPF chicks, were divided into SE group (30 chicks), mortality group (10 chicks), both orally inoculated (1.0 ml) with SE PT1 (1 × 108 colony-forming unit per 1.0 ml), and one control group (30 chicks). The chicks were sacrificed at 6 and 12 hours, and days 1, 2, 3, 5, 7, 10, 14, and 21 post-inoculation (pi). Samples were collected for bacterial isolation, histological examination, and ultrastructural examination.
RESULTS: Starting from day 2 pi, the body weight in the SE group significantly (p < 0.05) decreased. The SE isolation percentages from the liver, spleen, mid-intestinal content, cecal content, cecal tonsil, blood, and cloacal swab were 0.73, 0.77, 0.33, 0.33, 0.36, 0.40, and 0.30, respectively. The isolation percentage in the liver was significantly (p < 0.05) higher than the blood and cloacal swab. The villi heights and crypt depths in the SE group were significantly (p < 0.05) greater and smaller, respectively. Ultrastructurally, erosion and necrosis were observed in the microvilli of the cecal tonsil. The bacteria were engulfed by macrophages at the interepithelial clefts of the M-like M cells.
CONCLUSION: It was concluded that the inoculation of SE PT 1 in one-day-old chicks caused a systemic infection with diarrhea, a decrease in the body weight and villi height in the duodenum, jejunum, and ileum, and high bacterial loading in the liver with mild gross and histological lesions of organs, erosion, and necrosis of microvilli and low mortality. The bacteria entered the body system from the intestinal tract through the interepithelial clefts of the M-like M cells of the cecal tonsil.
Search for antibacterial agents from Malaysian rainforest and tropical plants

Othman M, Genapathy S, Liew PS, Ch'ng QT, Loh HS, Khoo TJ, et al.

Nat Prod Res, 2011 Nov;25(19):1857-64.
PMID: 21838540 DOI: 10.1080/14786419.2010.537274

The world's rainforests hold untold potential for drug discovery. Rainforest plants are thought to contain evolved defensive active metabolites of greater diversity compared to plants from temperate regions. In recent years, the interest and overall output from pharmaceutical companies on novel antibacterial agents has diminished at a time when there is a critical need for them to fight the threat of resistance. In this study, we have investigated the antimicrobial properties of 21 flowering plants from 16 different families against six bacterial strains consisting of two Gram negative and four Gram positive. Using the pour plate disc diffusion technique, almost all extracts from these plants were found to be active against some of the bacterial strains tested. The most interesting and active plants with broad spectrum activities include Duabanga grandiflora, Acalypha wilkesiana and Pseuduvaria macrophylla where the minimum inhibitory concentration, minimum bactericidal concentration and phytochemical analysis were carried out. This is the first report describing the antimicrobial and phytochemical properties of D. grandiflora and P. macrophylla. Our findings support the utilisation of higher plant species in the search for new antimicrobial molecules to combat new emerging infective diseases and the problem of drug resistant pathogens.