A single gene encoding the fiber is responsible for variations in virulence in the fowl adenoviruses

Abstract

Intertypic recombinant fowl adenoviruses (FAVs) were generated to determine regions of the viral genome involved in virulence. Recombinants were produced with two serotype 8 FAVs, mildly virulent CFA 3 and hypervirulent CFA 40. Restriction endonuclease fragments from the genomes of the two FAVs were used to transfect primary chicken kidney cells. Virulence testing of these recombinants located the region responsible for differences in virulence to an 8.4-kb fragment of the genome located between kb 26.6 and 35.0. According to data available for a serotype 10 FAV that had been partially characterized in the laboratory, this segment of the genome contained three genes of known identity (100K, 33K, and pVIII) and a region between kb 31 and 35 with unknown coding potential (although this information subsequently became available for a serotype 1 FAV, CELO). Therefore, the region between kb 30.5 and 34.5 was sequenced. The results revealed that the unknown region encoded a fiber gene on the right strand and several small open reading frames of unknown identity on the left strand. Further recombinant viruses containing defined exchanges within the 4-kb fragment were constructed, and virulence testing of these viruses indicated that the fiber was responsible for differences in virulence for CFA 40 and CFA 3.

Clinicopathological characterization and genomic sequence differences observed in a highly virulent fowlAviadenovirusserotype 4

“…With regard to the virulence association of fibre-2, previous studies reported that this protein has an effect on the virulence of fowl adenovirus (Pallister et al, 1996). Additionally, aligning fibre-2 amino acid sequences of several FAdVs-4 which induce HHS and apathogenic strains, we noted particular amino acid substitutions between both kinds of strains (Marek et al, 2012).…”

“…Previous studies have shown the important role of fibre-2 in virulence of fowl aviadenoviruses (Pallister et al, 1996). Some authors suggested some amino acids relevant for virulence based on the amino acid comparison of strains which induce HHS and non-virulent strains, positions located at 219 and 380 in the fibre-2 protein of KR5 (Marek et al, 2012).…”

The role of egg drop syndrome virus in acute respiratory disease of goslings

“…Finally, the purification of the virus by ultracentrifugation in a caesium-chloride gradient in earlier studies resulted in a virus stock that had lost its ability to haemagglutinate, even though its infectivity in tissue culture and eggs remained unaltered. The tissue tropism of adenoviruses is primarily determined by epitopes on the fibre protein, the haemagglutinin (Pallister et al, 1996). It is likely, therefore, that changes in the haemagglutination properties might influence pathogenicity, even if in vitro infectivity is retained.…”

A novel monoclonal antibody efficiently blocks the infection of serotype 4 fowl adenovirus by targeting fiber-2

“…Among the structural proteins encoded by adenovirus, the fiber protein plays vital roles in mediating viral infection and determining the antigenicity [ 17 – 19 ]. In contrast to other adenoviruses, FAdV-1, FAdV-4 and FAdV-10 encode two fiber proteins, designated fiber-1 and fiber-2 [ 17 ].…”