Molecular characterization of fowl adenovirus isolate of Malaysia attenuated in chicken embryo liver cells and its pathogenicity and immunogenicity in chickens

Abstract

Fowl adenovirus (FAdV) is the causative agent of inclusion body hepatitis (IBH) in chickens with significant economic losses due to high mortality and poor production. It was objectives of the study to attenuate and determine the molecular characteristic of FAdV isolate (UPM1137) of Malaysia passages in primary chicken embryo liver (CEL) cells. The cytopathic effect (CPE) was recorded and the present of the virus was detected by polymerase chain reaction (PCR). Nucleotide and amino acid changes were determined and a phylogenetic tree was constructed. The pathogenicity and immunogenicity of the virus at passage 35 (CEL35) with virus titre of 106.7TCID50/mL was determined in day old specific pathogen free (SPF) chicks via oral or subcutaneous route of inoculation. The study demonstrated that the FAdV isolate was successfully propagated and attenuated in CEL cells up to 35th consecutive passages (CEL35) with delayed of CPE formation within 48 to 72 post inoculation (pi) from CEL20 onwards. The virus caused typical CPE with basophilic intranuclear inclusion bodies, refractile and clumping of cells. The virus is belong to serotype 8b with substitution of amino acid at position 44, 133 and 185 in L1 loop of hexon gene and in knob of fiber gene at position 348 and 360 at CEL35. It is non-pathogenic, but immunogenic in SPF chickens. It was concluded that the FAdV isolate was successfully attenuated in CEL cells with molecular changes in major capsid proteins which affect its infectivity in cell culture and SPF chickens.

Isolation and Molecular Characterization of Fowl Adenoviruses Associated with Inclusion Body Hepatitis-hydropericardium Syndrome in Broiler Chickens in Egypt

“…In addition, FAdV virus isolation was carried out using primary CEL and cytopathic effects were noticed after 24 hours of virus inoculation in the form of cell rounding and small focal cells' areas detachment from the surface. Similar CPE in CEL of FAdVs was previously described by (Soumyalekshmi et al, 2014;Mohamed Sohaimi et al, 2019).…”

“…Recently, outbreaks of IBH-HPS have hit several countries over the globe such as Japan (Nakamura et al, 2011), Malaysia (Mohamed Sohaimi et al, 2019), China (Li et al, 2018), India (Raj et al, 2018;Suohu et al, 2021) Spain (Oliver-Ferrando et al, 2017), Iran (Morshed et al, 2017), South Africa (Maartens et al, 2014) and Saudi Arabia (Hemida and Alhammadi 2017). The disease mortalities reach 5-10% and may surge to 30% if it is co-infected with other immunosuppressive agents, such as Chicken infectious anemia virus CIAV and Infectious bursal disease virus (IBDV) (McFerran and Smyth, 2000).…”

Historical Investigation of Fowl Adenovirus Outbreaks in South Korea from 2007 to 2021: A Comprehensive Review

“…For instance, molecular characterization and phylogenetic studies of recent FAdV isolates from clinical cases in Malaysia revealed FAdV-8b as the predominant serotype behind IBH outbreaks among commercial broilers, similar to South Korea [48]. Interestingly, Malaysia does not have a history of FAdV outbreaks caused by serotypes other than FAdV-8b, which may be attributable to Malaysia being a self-sufficient producer that does not rely on international trade for poultry products, thus limiting the introduction of other serotypes [87][88][89]. That is, the Malaysian FAdV-8b cases may be ascribable to the "carry-over" or dissemination of viruses by wild birds; this may also apply to the Korean FAdV-8b cases that surged, although these assumptions require further corroboration.…”

Transcriptome Analysis of Genes Responding to Infection of Leghorn Male Hepatocellular Cells With Fowl Adenovirus Serotype 4

“…FAdV-4 is the primary pathogen of HHS, which has an immunosuppressive potential ( 51 , 52 ). Previous studies have shown that apoptosis and inflammatory signaling activation are potent inducers of immunosuppressive mechanisms ( 4 , 53 ).…”