Molecular and Immunology Studies of Vaccinated Chickens with Newcastle Disease Virus Genotype II and Genotype VII
Date
2021
Authors
Pandarangga, Putri
Editors
Advisors
Hemmatzadeh, Farmid
McAllister, Milton
McAllister, Milton
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Abstract
Since it was discovered in 1926 in England and Indonesia, Newcastle Disease Virus
(NDV), especially from Genotype VII (GVII), has caused death in chickens that have been
vaccinated using the NDV vaccine Genotype II (GII), known as a heterologous vaccine.
Vaccines from the GVII strain, also known as homologous vaccines, have prevented NDV
outbreaks. Determination of the differences between the two vaccines was done using a
transcriptomic method to determine the response of chickens at the genetic level; with
serology approach and viral loading counting; and differences between the two strains
genetically using whole-genome sequences. Thirty, three-week-old specific-pathogen-free
(SPF) chickens were divided into three groups. The first group was a negative control, the
second group was vaccinated with GIIvacc, and the third group was vaccinated with
GVIIvacc. Treatment groups were immunized with vaccines on day 14 and day 28. Sera were
obtained from all groups on day 28 for the serology tests. On day 42, the spleen was collected
for transcriptomic. Meanwhile, the whole genome sequence samples were obtained from the
NDV outbreak in 2015 in Indonesia, Genotype II strain, and challenge strain to determine
vaccine effectiveness
Spleen transcriptomic showed that GVIIvacc down-regulates the neuroinflammation
pathway but increases the communication activity among neurons as part of the
synaptogenesis pathway. Thus, it is speculated that suppressing the neuroinflammation
pathway is associated with protecting the nervous system in chickens from excess leukocytes
and cytokine activity. Meanwhile, GIIvacc only prevents apoptosis by suppressing PERK/
ATF4/CHOP as part of the unfolded protein response (UPR) pathway. Thus, the use of
GVIIvacc should be considered in countries where GVII strain causes NDV outbreaks. The transcriptomic result aligned with serological and challenged virus test that
homologous vaccine (GVIIvacc) gave better protection by reducing the viral shedding and
had higher protective antibodies than a heterologous vaccine (GIIvacc). In particular, the
Hemagglutination Inhibition (HI) test showed that antibody titers were higher when tested
with homologous antigen. However, the cleavage site of the Fusion (F) protein from GII and
GVII were used as alternative antigens in an ELISA, did not perform well to obtain the
relevant antibody titer. After being challenged with GVII, viral shedding from vaccinated
chickens with GVIIvacc was significantly reduced compared to chickens vaccinated with
GIIvacc. Both chicken groups showed no clinical signs.
The whole-genome sequence and phylogenetic tree results showed that GVII is still
the dominant NDV strain that causes NDV outbreaks in Indonesia. In addition, ITA strains
for testing the vaccine's efficacy belong to GVI. Hence, using GVI as a heterologous strain
from the field as a challenge strain for effective vaccine testing should be considered in
veterinary laboratories, especially in Indonesia. All the results from my research study
suggested that to combat NDV, the vaccine, antigen for antibody titer, and antigen as
challenge strain for effectivity vaccine need to be homologous or coming from the NDV
genotype, which causes an outbreak in the field.
School/Discipline
School of Animal and Veterinary Sciences
Dissertation Note
Thesis (Ph.D.) -- University of Adelaide, School of Animal and Veterinary Sciences, 2021
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