Department of Veterinary Medicine

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Author: search.filters.author.Paldurai, Anandan

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    Development of a recombinant Newcastle disease virus-vectored vaccine for infectious bronchitis virus variant strains circulating in Egypt
    (Springer Nature, 2019-02-11) Abozeid, Hassanein H.; Paldurai, Anandan; Varghese, Berin P.; Khattar, Sunil K.; Afifi, Manal A.; Zouelfakkar, Sahar; El-Deeb, Ayman H.; El-Kady, Magdy F.; Samal, Siba K.
    Infectious bronchitis virus (IBV) causes a major disease problem for the poultry industry worldwide. The currently used live-attenuated vaccines have the tendency to mutate and/or recombine with circulating field strains resulting in the emergence of vaccine-derived variant viruses. In order to circumvent these issues, and to develop a vaccine that is more relevant to Egypt and its neighboring countries, a recombinant avirulent Newcastle disease virus (rNDV) strain LaSota was constructed to express the codon-optimized S glycoprotein of the Egyptian IBV variant strain IBV/Ck/EG/CU/4/2014 belonging to GI-23 lineage, that is prevalent in Egypt and in the Middle East. A wild type and two modified versions of the IBV S protein were expressed individually by rNDV. A high level of S protein expression was detected in vitro by Western blot and immunofluorescence analyses. All rNDV-vectored IBV vaccine candidates were genetically stable, slightly attenuated and showed growth patterns comparable to that of parental rLaSota virus. Single-dose vaccination of 1-day-old SPF White Leghorn chicks with the rNDVs expressing IBV S protein provided significant protection against clinical disease after IBV challenge but did not show reduction in tracheal viral shedding. Single-dose vaccination also provided complete protection against virulent NDV challenge. However, prime-boost vaccination using rNDV expressing the wild type IBV S protein provided better protection, after IBV challenge, against clinical signs and significantly reduced tracheal viral shedding. These results indicate that the NDV-vectored IBV vaccines are promising bivalent vaccine candidates to control both infectious bronchitis and Newcastle disease in Egypt.
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    Sequence analysis of fusion protein gene of Newcastle disease virus isolated from outbreaks in Egypt during 2006
    (2011-05-18) Mohamed, Mahmoud HA; Kumar, Sachin; Paldurai, Anandan; Samal, Siba K
    Background: Newcastle disease virus represents APMV-1 and is the most characterized among all APMV types. The F protein cleavage site sequence is a well-characterized determinant of NDV pathogenicity in chickens. In this study, the sequences of fusion protein (F) gene of three Newcastle disease virus (NDV) strains isolated from outbreak in chickens in the Al-Sharkia province of Egypt in 2006 were determined. Findings: The viral genomic RNAs were extracted from the infective allantoic fluid and F gene is amplified using primer sets designed from the available sequences of NDV strains from GenBank. The pathogenicity of NDV strains was determined by three internationally recognized tests mean death time, intracerebral pathogenicity index, and intravenous pathogenicity index. The phylogenetic analysis showed that the Egypt isolates are closely related with the genotype II of class II NDV strains. Conclusions: The sequences of the F genes of the 2006 Egypt isolates are closely related to that of the 2005 Egypt isolate from the same province suggesting that these strains are probably circulating in the vaccinated bird population in Egypt until development of an outbreak.
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    DETERMINATION OF GENETIC FACTORS INVOLVED IN THE VIRULENCE OF NEWCASTLE DISEASE VIRUS
    (2012) Paldurai, Anandan; SAMAL, SIBA K; Veterinary Medical Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Newcastle disease is economically the most important disease of poultry. The causative agent Newcastle disease virus (NDV) is a large, enveloped virus containing single stranded non-segmented negative-sense RNA genome. The genome of NDV contains six genes in the order of 3'Leader-N-P-M-F-HN-L-5'Trailer. NDV has at least three different genome size categories: 15,186, 15,192 and 15,198 nucleotides (nt) in length. The virulence of NDV is considered to be contributed by multiple genes. The importance of genome lengths and the roles of individual genes in virulence of NDV in its natural host, chickens, have not been determined. In this study, the effects of naturally occurring nucleotide insertions in NDV genome and roles of individual genes in the virulence of NDV in chickens were determined. To achieve this goal, reverse genetic systems for two strains of NDV were established for a highly virulent strain Texas GB (GBT) and a moderately virulent strain Beaudette C (BC). Both GBT and BC are isolated from chickens and belong to genotype II of class II NDV strains and have the genome length of 15,186 nt. The 6- and 12-nt insertions in the backbones of rBC and rGBT showed little attenuation in virus replication and in pathogenicity of the parental recombinant viruses. The reciprocal swap between NDV strains BC and GBT for the genes, nucleocapsid protein (N), phosphoprotein (P), matrix protein (M), fusion protein (F), hemagglutinin-neuraminidase protein (HN) and large polymerase (L) protein genes, showed that F protein gene is most important for NDV virulence, followed by the L protein gene. M, HN, N and P genes appeared not to affect the pathotypes of their parental recombinant viruses in chickens. The observations of the present study paves the way for future directions: to use the naturally occurring insertion site in the coding region of the phosphoprotein gene for insertion of potential marker sequences; to determine the amino acid residues important in fusion protein and polymerase protein for replication and pathogenesis of NDV.