Molecular typing of fowl adenoviruses, isolated in Hungary recently, reveals high diversity

Molecular typing of 26 recent fowl adenovirus (FAdV) isolates obtained in Eastern Hungary between 2006 and 2011 was performed. The viruses were isolated on primary chicken embryo liver cell cultures from carcasses of chickens, sent for diagnostic investigation. The isolates were subjected to a PCR to amplify a fragment from the hexon gene. Sequence analysis of the amplicons revealed the presence of all the five FAdV species in the country, among them FAdV-B, which has been barely found in Hungary before. The three strains classified as FAdV-B might represent a novel type within this species, as their nucleotide sequence identity to strain 340 (type FAdV-5) is below the commonly accepted intratype limit. Most of the strains (63%) were classified into species FAdV-E (12 strains) and FAdV-D (7 strains) in the study. Four of the isolates proved to be the mixture of two adenovirus strains belonging to two different FAdV types, in three from these four cases, these two types even belonged to two different species. Analysing the pathological findings bolsters certain established connections between some FAdV types and disease conditions. Gizzard erosion was found in connection with FAdV-1 strains only, and inclusion body hepatitis with FAdV-D and -E strains.