Sequence and Phylogenetic Study of Two Fowlpox Virus Isolates Obtained from Layer Chickens and Red Mite (Dermanyssus gallinae) in 2016

This study was conducted to characterize two fowlpox viruses isolated in Iran and study their phylogenic relationship.

The aim of this study was to determine the identity of two pox viruses recovered from a tissue sample with typical lesions of fowl pox and red mites from a laying farm. Fowl pox in poultry industry causes significant economic losses associated with decreased egg production, reduced growth, blindness and increased mortality. The pox virus, by direct or indirect contact, may also be transmitted through vectors such as mites and fleas. Dermanyssus gallinae also known as the poultry red mite is the most important blood feeder ectoparasite affecting poultry, in particular, laying hens. In addition to its significant economic losses, it is considered as a potential vector for a number of important avian pathogens.

Both isolates were inoculated to chorioallantoic membrane (CAM) of embryonated chicken eggs, detected by specific PCR for pox virus 4b gene and characterized by sequencing and phylogentic analysis.

Both isolates developed pock lesions in CAM of embryonated eggs. A 578 bp fragment of the poxvirus 4b gene was amplified in both isolates by PCR. The sequence analyses revealed that the two isolates were 100% identical and placed in the same branch. The nucleotide sequence of these two isolates showed a similarity of 73 to 100% to the other selected avian pox sequences available in the GenBank.

These results confirmed that Dermanyssus gallinae are considered to be an important vector for the spread of fowl pox virus in the flocks. Therefore, controlling the red mites in poultry farms will not only inhibit problems such as blood feeding, decreased production and reduced growth rate, it can reduce the transmission of diseases and pathogenic agents in the farms.