Characterization of the Fibropapilloma-associated Chelonid herpesvirus 5 (ChHV5)

Fibropapillomatosis (FP) of marine turtles is a neoplastic disease associated with infection by an ancient turtle herpesvirus named Chelonid herpesvirus 5 (ChHV5; previously also known as FP-THV or CFPHV).

Unfortunately, serial propagation in cell cultures of ChHV5 has not yet been successful. Therefore, the knowledge about features of basic virology, pathogenesis, and epidemiology are only slowly uncovered.

We have cloned the viral genome as a bacterial artificial chromosome (BAC), from which the viral sequence was determined [1]. Based on these new sequences, we have developed anti-peptide sera, which recognize particular proteins of ChHV5, for example the capsid protein VP26. Using this serum, we have identified small foci of ChHV5 replication on the tumor surface [2]. Moreover, based on rafts consisting of persistently infected fibroblasts, overlaid with uninfected keratinocytes, we established the first in vitro culture for ChHV5 [3]. Using ELISA-based serology, we have shown that ChHV5 is widely distributed and circulates among healthy turtles in the Pacific and in the Atlantic. However, it seems as if tumor-formation is needed for efficient transmission of the virus [4].

Publications

1. Ackermann M, Koriabine M, Hartmann-Fritsch F, de Jong PJ, Lewis TD, Schetle N, et al. The genome of Chelonid herpesvirus 5 harbors atypical genes.
PLoS One. 2012;7(10):e46623.

2. Work TM, Dagenais J, Balazs GH, Schettle N, Ackermann M. Dynamics of Virus Shedding and In Situ Confirmation of Chelonid Herpesvirus 5 in Hawaiian Green Turtles With Fibropapillomatosis.
Vet Pathol. 2015;52(6):1195-201.

3. Work TM, Dagenais J, Weatherby TM, Balazs GH, Ackermann M. In-vitro replication of Chelonid herpesvirus 5 in organotypic skin cultures from Hawaiian green turtles (Chelonia mydas).
J Virol. 2017.

4. Work TM, Dagenais J, Willimann A, Balazs G, Mansfield K, Ackermann M. 2020. Differences in Antibody Responses against Chelonid Alphaherpesvirus 5 (ChHV5) Suggest Differences in Virus Biology in ChHV5-Seropositive Green Turtles from Hawaii and ChHV5-Seropositive Green Turtles from Florida.
J Virol. 2020 Jan 31;94(4):e01658-19.

Cover Illustration: Fibropapillomatose