Identification, sequencing and molecular analysis of Chp4, a novel chlamydiaphage of Chlamydophila abortus belonging to the family Microviridae

Abstract

Members of the familyMicroviridaehave been identified in a number of chlamydial species infecting humans (phage CPAR39 inChlamydophila pneumoniae), other mammals (φCPG1 inChlamydophila caviae, Chp2 inChlamydophila abortusand Chp3 inChlamydophila pecorum) and birds (Chp1 inChlamydophila psittaci). This study describes the identification and genome sequencing of Chp4, an icosahedral, 4530 bp, ssDNA phage inC. abortus. Chp4 is predicted to contain eight ORFs, six of which could be assigned putative functions based on sequence similarity to characterized bacteriophage. Gene order and content were highly conserved amongst chlamydiaphage, with the highest sequence variability occurring in the IN5 and INS variable regions of the VP1 major coat protein, which has been associated with host cell recognition and binding. Phylogenetic analysis of VP1 indicated that Chp4 is a member of theChlamydiamicrovirus, and is most closely related to phage φCPG1 and CPAR39.