Genomic Characterization and Tissue Tropism of a Potentially Novel Mupapillomavirus Isolated from the Anal Canal

B. J. KOCJAN; L. HOSNJAK; D. CHOUHY; A. A. GIRI; M. POLJAK

Congreso; American Society for Microbiology 115th General Meeting; 2015

Background: Human papillomaviruses (HPVs) represent a large family of DNA viruses, etiologically linked with various neoplasms of the skin and mucosa, taxonomically classified into genera, species and types. Mupapillomavirus (Mu-PV) genus currently consists of only two HPV types: HPV1 and HPV63 identified in 1980 and 1993, respectively, both associated with sporadic cases of skin warts. In this study, a potentially novel Mu-PV type, designated as FJ947082, was fully cloned, sequenced and genetically characterized. The tissue predilection of a novel type was assessed on a collection of skin, mucosal and mucocutaneous clinical samples. Methods: Partial FJ947082 L1-gene sequence, closely related to Mu-PVs, was initially obtained from a skin swab sample using CUT primers. Complete viral genome was amplified from an anal swab sample of a 36-year old male patient with HPV53-positive anal warts using inverse long-range PCR, cloned into a plasmid vector, and sequenced by primer walking. A quantitative FJ947082 type-specific real-time PCR was developed and used to determine the prevalence of a novel HPV type in 100 tissue specimens of skin warts, 95 swabs of the anal canal (mainly from patients with anal warts), and 100 swabs of clinically normal oral mucosa. Phylogenetic evaluation, performed using a maximum-likelihood algorithm, was based on the entire L1 gene sequence of FJ947082 and all currently officially recognized HPV types. Results: Novel Mu-PV genome comprises 7,227-bp (G+C content of 37.8%), and contains five early (E1, E2, E4, E6 and E7) and two late genes (L1 and L2), and the non-coding regulatory region between L1 and E6 ORFs. Phylogenetic analysis confirmed that FJ947082 clusters to the Mu-PV genus. With an L1 nucleotide sequence identity of 66.3% and 66.7% to HPV1 and HPV63, respectively, FJ947082 is classified as a new type in a new Mu-PV species Mu-3. Using real-time PCR, novel HPV was detected in 6/100 skin warts, 3/95 anal canal samples, and in none of the oral cavity samples. Conclusion: With full characterization of a third member of Mu-PV genus we expand the current knowledge of genetic diversity and tissue tropism of this PV genus. The potential clinical importance of a novel Mu-PV type is under investigation.