The sulcular epithelium as a reservoir for herpes simplex virus in man. J Periodontol ; Detection of herpesviruses and periodontal pathogens in subgingival plaque of patients with chronic periodontitis, generalized aggressive periodontitis, or gingivitis. Prevalence of some herpesviruses in gingival crevicular fluid. J Clin Virol ; Effect of periodontal mechanical treatment on herpesviruses in gingival crevicular fluid of patients with chronic periodontitis. Armitage GC. Development of a classification system for periodontal diseases and conditions. Ann Periodontol ; Silness J, Loe H.
Periodontal disease in pregnancy. Correlation between oral hygiene and periodontal condtion. Acta Odontol Scand ; Loe H, Silness J. Prevalence and severity.
Gingival sulcus bleeding — A leading symptom in initial gingivitis. Helv Odontol Acta ; Prevalence of human cytomegalovirus and Epstein-Barr virus in subgingival plaque at peri-implantitis, mucositis and healthy sites. A pilot study. Int J Oral Maxillofac Surg ; Identification of herpesviruses types 1 to 8 and human papillomavirus in acute apical abscesses. J Endod ; Herpesviruses in chronic and aggressive periodontitis patients in an Indian population.
J Oral Sci ; Contreras A, Slots J. Typing of herpes simplex virus from human periodontium.
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A Cladogram depicting relationships among viruses in the order Herpesvirales , based on the conserved regions of the terminase gene. The Bayesian maximum-likelihood tree was rooted by using bacteriophages T4 and RB Alloherpesviridae viruses infect fish and amphibians. The common ancestor of this family is thought to have diverged from the common ancestor of the family Herpesviridae herpesviruses that infect reptiles, birds, and mammals 6.
According to phylogenetic analysis of specific genes, the family Alloherpesviridae seems to be subdivided into 2 clades 6 Figure 2 , panel B. The first clade comprises anguillid and cyprinid herpesviruses, which possess the largest genomes in the order Herpesvirales — kb. The second clade comprises ictalurid, salmonid, acipenserid, and ranid herpesviruses, which have smaller DNA genomes — kb.
Herpesvirus acts with the cytoskeleton and promotes cancer progression
Figure 3. Electron micrograph image of cyprinid herpesvirus 3 virion. Adapted with permission from Mettenleiter et al. The CyHV-3 structure is typical of viruses of the order Herpesvirales. An icosahedral capsid contains the genome, which consists of a single, linear, double-stranded DNA molecule. The capsid is covered by a proteinaceous matrix called the tegument, which is surrounded by a lipid envelope derived from host cell trans-golgi membrane 7 Figure 3.
The envelope contains viral glycoproteins 3. The diameter of the entire CyHV-3 particle is — nm 3 , 8. The genome of CyHV-3 is a kb, linear, double-stranded DNA molecule consisting of a large central portion flanked by two kb repeat regions, called the left and right repeats 9. The genome size is similar to that of CyHV-1 but larger than that of other members of the order Herpesvirales, which are generally — kb.
Chemokine Subversion by Human Herpesviruses
These 8 ORFs are consequently present as 2 copies in the genome 9. CyHV-3 encodes several genes that could be involved in immune evasion processes, such as ORF16, which codes for a potential G-protein coupled receptor; ORF, which codes for an IL homolog; and ORF12, which codes for a tumor necrosis factor receptor homolog. Within the family Alloherpesviridae , anguillid herpesvirus 1 is the closest relative of CyHV-3 that has been sequenced Each of these viruses possesses 40 ORFs exhibiting similarity.
Six ORFs encode proteins with closest relatives in virus families such as Poxviridae and Iridoviridae 9. Neither thymidylate kinase nor B22R has been identified previously in a member of the order Herpesvirales. Despite their distant geographic origins, these strains exhibit high sequence identity. Low diversity of sequences among strains seems to be a characteristic of the CyHV-3 species.
Despite this low diversity, molecular markers enabling discrimination among 9 genotypes 7 from Europe and 2 from Asia have been identified Because CyHV-3 possesses the largest genome among members of the order Herpesvirales, it provides a model for mutagenesis of large DNA viruses. Recently, the CyHV-3 genome was cloned as a stable and infectious bacterial artificial chromosome, which could be used to produce CyHV-3 recombinants The structural proteome of CyHV-3 was recently characterized by using liquid chromatography tandem mass spectrometry A total of 40 structural proteins, comprising 3 capsid, 13 envelope, 2 tegument, and 22 unclassified proteins, were described.
CyHV-3 is widely cultivated in cell lines derived from koi fin, C. Other cell lines have been tested, but few have been found to be permissive for CyHV-3 infection Table 1.
The CyHV-3 replication cycle was recently studied by use of electron microscopy 7. Its morphologic stages suggested that it replicates in a manner similar to that of members of the family Herpesviridae. Capsids leave the nucleus by budding at the inner nuclear membrane, resulting in formation of primary enveloped virions in the perinuclear space.
The primary envelope then fuses with the outer leaflet of the nuclear membrane, thereby releasing nucleocapsids into the cytoplasm. Final envelopment occurs by budding into trans-golgi vesicles. Because CyHV-3 glycoproteins have little or no similarity with those of members of the family Herpesviridae , identification of the CyHV-3 glycoproteins involved in entry and egress will require further study. Figure 4. Effects of temperature on cyprinid herpesvirus 3 replication in Cyprinus carpio carp brain cells.
These results suggest that CyHV-3 can persist asymptomatically for long periods in the fish body when the temperature prevents virus replication; bursts of new infection occur after exposure to permissive temperatures. In , the first mass deaths of common and koi carp were reported in Israel and the United States 3.
However, analyses of samples from archives determined that the virus had been in wild common carp since in the United Kingdom Worldwide, CyHV-3 has caused severe financial and economic losses in the koi and common carp culture industries. Common and koi carp are the only species known to be affected by CyHV-3 infection Numerous fish species, cyprinid and noncyprinid, were tested for their ability to carry CyHV-3 asymptomatically and to spread it to unexposed carp 21 — 23 Table 2.
Cohabitation experiments suggest that goldfish, grass carp, and tench can carry CyHV-3 asymptomatically and spread it to unexposed common carp. Hybrids koi—goldfish and koi—crucian carp die of CyHV-3 infection CyHV-3 affects carp of all ages, but younger fish 1—3 months, 2. Recently, the susceptibility of young carp to CyHV-3 infection was analyzed by experimental infection Figure 5. Skin of carp as a portal of entry for cyprinid herpesvirus 3.
A schematic representation of the system used to restrict viral inoculation to the fish skin is shown on the Several researchers have postulated that the gills might be the portal of entry for CyHV-3 17 , 26 — 28 ; however, this hypothesis was recently refuted Bioluminescent imaging and an original system for performing percutaneous infection restricted to the posterior part of the fish showed that the skin covering the fin and body mediated entry of CyHV-3 into carp 29 Figure 5. This study, together with an earlier study of the portal of entry of a rhabdovirus infectious hematopoietic necrosis virus in salmonids 30 , suggests that the skin of teleost fish represents an efficient portal of entry for certain viruses.
The skin of teleost fish is a stratified squamous epithelium that, unlike its mammalian counterpart, is living and capable of mitotic division at all levels, even the outermost squamous layer. The scales are dermal structures. More extensive studies are needed to demonstrate that the skin is the only portal of entry of CyHV-3 into carp.
After initial replication in the epidermis 29 , the virus is postulated to spread rapidly in infected fish, as indicated by detection of CyHV-3 DNA in fish tissues As early as 24 hours postinfection, CyHV-3 DNA was recovered from almost all internal tissues including liver, kidney, gut, spleen, and brain 27 , where viral replication occurs at later stages of infection and causes lesions. One hypothesis regarding the rapid and systemic dissemination indicated by PCR is that CyHV-3 secondarily infects blood cells. Virus replication in organs such as the gills, skin, and gut at the later stages of infection represents sources of viral excretion into the environment.
Gilad et al. All members of the family Herpesviridae exhibit 2 distinct life-cycle phases: lytic replication and latency. Latency is characterized by maintenance of the viral genome as a nonintegrated episome and expression of a limited number of viral genes and microRNAs. At the time of reactivation, latency is replaced by lytic replication. Latency has not been demonstrated conclusively in members of the family Alloherpesviridae.
However, some evidence supports existence of a latent phase. Furthermore, the virus persisted in a wild population of common carp for at least 2 years after the initial outbreak Finally, St-Hilaire et al. Whether the observations described above reflect latent infection, as described for the family Herpesviridae , or some type of chronic infection, remains to be determined. Similarly, the carp organs that support this latent or chronic infection still need to be identified.
Horizontal transmission of CyHV-3 in feces 26 and secretion of viral particles into water 21 have been demonstrated. The skin of carp acts as the portal of entry of CyHV-3 and the site of early replication The early replication of the virus at the portal of entry could contribute not only to the spread of the virus within infected fish but also to the spread of the virus throughout the fish population.
As early as 2—3 dpi, infected fish rubbed against other fish or against objects. Latent virus is usually detected in lymphoid organs. The lymphocryptoviruses or gamma-1 herpesviruses include EBV HHV4 and related viruses of Old World primates such as chimpanzees Herpesvirus pan , orangutans Herpesvirus orangutan and gorillas Herpesvirus gorilla.
These viruses share tropism for B lymphocytes, a genomic architecture of group B or C and similar gene organization. In contrast, there is little nucleotide sequence homology or antigenic cross-reactivity between the lymphocryptoviruses and the rhadinoviruses or gamma-2 herpesviruses. The genus is exemplified by the herpes viruses of primates, such as the ateles virus of spider monkeys and the saimiri virus of squirrel monkeys and some viruses of horses equid herpesvirus 2; Telford et al.
The recently described human Kaposi's sarcoma-associated herpesvirus KSHV or HHV8 has been classified in this genus owing to its close similarity to the saimiri virus. The rhadinoviruses have a group B genome. The current classification of herpesviruses, which is based mainly on biological properties, does not help in defining evolutionary relatedness.
The distinction between the alpha, beta and gamma subfamilies has been somewhat blurred by more detailed molecular studies and by the discovery of new viruses that co-express the structural features of one subfamily and at least some biological properties of another. Good examples are HHV6 and HHV7, which are classified as betaherpesviruses on the basis of their genetic homology to human CMV although their primary T-cell tropism is a typical feature of gammaherpesviruses Berneman et al.
The rapid accumulation of DNA sequences provides increased opportunities to study molecular evolution and phylogenetic relationships.