Phylogenetic relationships among herpesviruses (HVs) of mammals, birds, and reptiles have been studied extensively, whereas those among other HVs are relatively unexplored. We have reconstructed the phylogenetic relationships among 13 fish and amphibian HVs using maximum likelihood and Bayesian analyses of amino acid sequences predicted from parts of the DNA polymerase and terminase genes. The relationships among 6 of these viruses were confirmed using the partial DNA polymerase data plus the complete sequences of the terminase, helicase, and triplex protein genes; the position of these viruses among all other sequenced HVs was also investigated using the complete terminase gene. The results established the monophyly of the fish and amphibian HVs (Alloherpesviridae) separate from the HVs of mammals, birds, and reptiles (Herpesviridae) and the single recognized HV of bivalve mollusks (Malacoherpesviridae) in the order Herpesvirales. Two major clades in the family Alloherpesviridae were recognized: one consisting of viruses from cyprinid and anguillid hosts and the other of viruses from ictalurid, salmonid, acipenserid, and ranid hosts. A comparison of virus and host phylogenies suggested that closely related HVs in this family may have coevolved with their hosts, whereas significant codiversification was not apparent for the more distantly related viruses.

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Phylogenetic relationships in the family Alloherpesviridae.

Herpesviruses are host specific pathogens that are widespread among vertebrates. Genome sequence data demonstrate that most herpesviruses of fish and amphibians are grouped together (family Alloherpesviridae) and are distantly related to herpesviruses of reptiles, birds and mammals (family Herpesviridae). Yet, many of the biological processes of members of the order Herpesvirales are similar. Among the conserved characteristics are the virion structure, replication process, the ability to establish long term latency and the manipulation of the host immune response. Many of the similar processes may be due to convergent evolution. This overview of identified herpesviruses of fish discusses the diseases that alloherpesviruses cause, the biology of these viruses and the host-pathogen interactions. Much of our knowledge on the biology of Alloherpesvirdae is derived from research with two species: Ictalurid herpesvirus 1 (channel catfish virus) and Cyprinid herpesvirus 3 (koi herpesvirus).

/pdf/herpesviruses-that-infect-fish-1z44k97cr9.pdf

Herpesviruses that infect fish

Skin tumours of fish are easily recognizable lesions, some of which have been known for centuries. Causes of fish tumour formation are varied and are often proposed to be multifactorial. In more than half of all cases examined by electron rnicroscopy and virological methods, virus or virus-hke particles were found in tumour tissues. So far, oncogenicity has been clearly demonstrated only for herpesviruses isolated from benign tumours. Classification of fish skin tumours, tumour-associated and turnour-inducing viruses, and the possible reasons for seasonal variation in slun tumour prevalence, are revlewed. It is postulated that fundamental principles determne the role of viruses in the induction of skin tumours of fish within a framework of different biological and environmental parameters.

https://www.int-res.com/articles/dao/19/d019p215.pdf

Role of Viruses in the induction of skin tumours and tumour-like proliferations of fish

A seasonal survey of skin tumor prevalence in walleyes (Stizostedion vitreum) was conducted during the ice-free period on Oneida Lake, New York in 1986. During the survey, 1,028 walleyes were collected and examined for the presence of lymphocystis disease, dermal sarcoma, discrete epidermal hyperplasia and diffuse epidermal hyperplasia. Skin growths were high in prevalence in early spring, low in prevalence during the summer, and again high in prevalence in the fall. Lymphocystis disease and dermal sarcoma were more frequently observed than either discrete or diffuse epidermal hyperplasia. Histologically, a moderate to severe inflammatory response was associated with dermal sarcoma in the early spring and late spring but not in the fall. Regardless of the time of year, varying degrees of inflammatory response were seen associated with lymphocystis disease. Samples were inadequate to assess seasonal trends in incidence of discrete and diffuse epidermal hyperplasia.

https://bioone.org/journals/Journal-of-Wildlife-Diseases/volume-24/issue-2/0090-3558-24.2.292/SEASONAL-PREVALENCE-OF-SKIN-TUMORS-FROM-WALLEYE-span-classgenus-speciesSTIZOSTEDION/10.7589/0090-3558-24.2.292.pdf

Seasonal prevalence of skin tumors from walleye (stizostedion vitreum) from oneida lake, new york

New viruses described in finfish from 1988–1992

. A new virus, provisionally named Herpesvirus vitreum, was isolated from hyperplastic epidermal tissue from a walleye, Stizostedion vitreum vitreum (Mitchill), taken in Saskatchewan, Canada. The virus, which was isolated in the walleye ovarian (WO) cell line, was identified as a herpesvirus on the basis of size (190–230 nm), morphology and apparent pattern of replication. The virus, which passes polycarbonate membranes of 200 nm mean pore diameter, was ether-labile. Virus replicated in WC-1 cells at 4 and 15°C, but not at 20°C. Although walleye cell lines (WO, WC-1, We-2) were susceptible to infection at 15°C, non-period cell lines were refractory. Syncytial formation and lysis occurred in susceptible cell lines. Virus was quantified by plaque assay at 13 to 15°C for two weeks. Replication was inhibited by 10-3.0m phosphonoacetate and by 10-5.0m 5-bromodeoxyuridine (BUDR), but addition of excess thymidine reversed the inhibition by BUDR. Viral replication in WO cells, but not in WC-1 cells, was inhibited by the antiherpetic drug acyclovir (10-5.0m). The relationship of the herpesvirus isolate and epithelial neoplasms was not determined.

T. Yamamoto

Papers

Characterization of Herpes virus vitreum isolated from hyperplastic epidermal tissue of walleye, Stizostedion vitreum vitreum (Mitchill)*