Summary
The Pigeon circovirus (PiCV) which contains a circular single
stranded DNA (approximately 2 kb) belongs to the genus Circovirusand the family Circoviridae . PiCV infections in pigeons
(Columba livia ) have been reported worldwide. Nowadays, pigeon
racing is becoming increasingly popular and considered to be a national
sport in China, and even, the greatest competitions of racing pigeons
are stake place in China. However, there is no epidemiologic data on
PiCV infections among racing pigeons in China. To trace the prevalence,
genetic variation and evolution of PiCV in sick and healthy racing
pigeons, 622 samples were collected from 11 provinces or municipalities
of China from 2016 to 2019. Samples were tested by polymerase chain
reaction. The results showed that the positive rate of PiCV was 19.3%
(120/622) at the sample level; 59.0% (23/39) at the club level,
suggesting that the virus was prevalent in Chinese racing pigeons. A
sequence analysis revealed that the cap genes of the PiCV strains
identified in our study display high genetic diversity and shared
nucleotide homologies of 71.9%–100% and amino acid homologies of
71.7%–100%. 28 and 37 unique amino acid substitutions were observed
among the cap proteins and rep proteins of our PiCV
strains, respectively. Furthermore, two initiation codons (GTG and ATT)
of cap gene were newly found. A cap -gene-based
phylogenetic analysis showed that the strains in this study could be
further divided into six groups (A, B, C, E, G, H and I) and some of our
strains are closely related to worldwide strains from different types of
pigeons. A large number of recombination events (31 events) were also
detected in the PiCV genomes from Chinese racing pigeons. These findings
suggest that PiCV strains circulating in China exhibits higher genetic
diversity.