EPSTEIN-BARR VIRUS AND CYTOMEGALOVIRUS-TWO HERPES VIRUSES WITH ORAL MANIFESTATIONS

INTRODUCTION: Epstein-Barr virus (EBV) and cytomegalovirus (CMV) are herpesviruses, which account for the majority of oral viral infections. Herpes simplex virus, varicellazoster virus, and Epstein-Barr virus infections nearly always result from reactivation of latent virus, while cytomegalovirus infections, besides presenting as reactivated disease, are almost as likely to present as a primary infection in susceptible hosts [1]. Herpesviruses are common in persons infected with the human immunodeficiency virus (HIV) [2]. The diseases or medical treatments that have cytostatic or cytotoxic effects also increase the risk of viral infections [1]. The general characteristic of CMV and EBV is presented in tabl. 1.

of oral viral infections.Herpes simplex virus, varicellazoster virus, and Epstein-Barr virus infections nearly always result from reactivation of latent virus, while cytomegalovirus infections, besides presenting as reactivated disease, are almost as likely to present as a primary infection in susceptible hosts [1].Herpesviruses are common in persons infected with the human immunodeficiency virus (HIV) [2].The diseases or medical treatments that have cytostatic or cytotoxic effects also increase the risk of viral infections [1].
The general characteristic of CMV and EBV is presented in tabl. 1.

Cytomegalovirus
Cytomegalovirus is responsible for a significant percentage of asymptomatic viral infections worldwide.During childhood, many people acquire primary infection with cytomegalovirus and if they later become immunosuppressed, such as occurs with human immunodeficiency virus (HIV), CMV is likely to become reactivated (4).For the medical doctors and dentists is important that between 11 and 24% of children attending day-care centers have CMV in their saliva [3].
Although virtually any cell or organ may be infected [8].Severe disease caused by CMV have been reported -CMV retinitis, gastritis, colitis, pneumonia, encephalitis and hepatitis [4].After hematopoietic stem cell transplantation cytomegalovirus is the most common cause of pneumonia within the first 120 days [3].There is a date that CMV within endothelial cells may contribute to vascular inflammation, vascular occlusion, and end-organ damage [3].

Epstein-Barr virus
EBV infection is transmitted from person to person by contact with infectious body fluids (saliva, breast milk etc).Oral contact with infectious saliva is the most common route of transmission.The active virus reproduces and enters the person's saliva, a process known as "shedding" [7] In EBV two peaks of infection are seen: the first in very young preschool children aged 1 -6and the second in adolescents and young adults aged 14 -20 [3].
In primary infection, EBV infects B cells and can cause mucocutaneous manifestations in infectious mononucleosis (IM) or acute EBV-associated syndromes such as Gianotti-Crosti syndrome and hemophagocytic syndrome [3, 5, 9].There are two different types of chronic active Epstein-Barr virus (CAEBV) infection: chronic EBV (CEBV) having persistent infectious mononucleosis -like illness with relatively good prognosis, and severe CAEBV (SCAEBV) infection that has rather severe manifestations and generally poor prognosis (10).Latent EBV infection may result in diseases such as hydroa vacciniforme, hypersensitivity to mosquito bites, and lymphoproliferative disorders such as plasmablastic lymphoma, oral hairy leukoplakia, and post-transplant lymphoproliferative disorders, particularly in immunocompromised patients.Latent EBV infection has also been implicated in Burkitt lymphoma, Hodgkin lymphoma, nasopharyngeal carcinoma, and Kikuchi histocytic necrotizing lymphadenitis [5,10].
Like all herpesviruses, EBV establishes a life-long, persistent infection of its host [7] and in the majority of humans without causing disease [5].JA Thomas, et coworkers published that in the literature are reports of EBV infection in normal T cells and neoplastic T-cell diseases.Generally EBV is held to infect B cells and epithelial cells [11].
In Table 2 are present the clinical findings of Cytomegalovirus infection and infectious mononucleosis concerning the general health.In Table 3

Uncommon sites of infections in immunocompetent individuals include EBV
• hairy leukoplakia Hairy leukoplakia is the second most common HIVassociated oral mucosal lesion and usually is localisated on the lateral borders of the tongue.The typical clinical appearance is vertical white folds oriented as a palisade along the borders of the tongue [3].
• nasopharyngeal carcinoma Preliminary investigations suggest that the presence of EBV genomes in neck metastases from an occult primary may be diagnostic and predictive of nasopharyngeal carcinoma [18].

IM
In the majority of cases of IM lymphadenopathy is present and the cervical lymph nodes are most commonly involved, but generalized lymphadenopathy may occur [12].Swelling of anterior and posterior cervical lymph nodes plus axillary, epitrochlear, mediastinal, and mesenteric nodes) or auricular adenopathy, marked adenopathy, or inguinal adenopathy are described [12].
Other manifestation of IM can be salivary gland enlargement.Several viruses have been associated with acute nonsuppurative salivary gland enlargement.The viruses responsible for the majority of virally induced salivary gland enlargement are paramyxovirus, cytomegalovirus HIV, and hepatitis C virus.Echoviruses, Epstein-Barr virus, parainfluenza virus, and choriomeningitis virus infections have been linked to occasional reports of nonsuppurative salivary gland enlargement [3].

CMV
The effects of human CMV on cellular functions which may be associated with the malignant phenotype include the expression of oncogenes and transcriptional activation of growth factors and interleukin synthesis [19].
In another study M. Melnick et coworkers discus the association of CMV and variety of malignancies, including brain, breast, lung, colon, and prostate.The authors concluded that CMV is an important component of tumorigenesis (20).
In oral cavity CMV may be present as a single large necrotic painful ulcer and less often as multiple ulcers, present for weeks or months at any site may be involved (3).Up to one-third of such ulcers are coinfected with other viruses of the herpes family, especially herpes simplex virus and varizella zoster virus (VZV) [3, 15,21].There have been occasional reports of mandibular osteomyelitis and tooth exfoliation associated with CMV and VZV infection [3].Some authors reported CMV oral lesions in HIV infected patients and emphasize that CMV mucosal ulceration may be the initial manifestation of AIDS [13,16,17,22].
The infection of CMV affects also the composition of the saliva: IgG, and albumin were higher in patients, but total protein were lower [23].

CONCLUSION:
The clinical manifestations of these viruses are similar and most commonly affected liver, spleen and lymph node.In the oral cavity the viral sins are unspecific and uncommon.
The dentist first can recognize the oral manifestations of the underlying disease, taking in a part that the number of immunocompromised population will get increase.

Tabl. 1 .
The main characteristic of EBV and CMV [1, 3, 4, 5, 6, 7] Cytomegalovirus b-herpesvirus HHV -5 body fluids (breast milk, saliva, urine, respiratory secretions) sexual contact blood transfusion during delivery organ transplant 60-70% of the adult population has been exposed Manifestation of CMV are more evident in immunocompromised population , such as organ transplant patients and who have AIDS Once exposed to CMV, this virus establishes latency within the connective tissue cells, such as the endothelium of blood vessels, mononuclear cells, white blood cells, and epithelial cells Primary infection may be asymptomatic or cause an infectious mononucleosis like disease Epstein-Barr virus HHV -4 body fluids (saliva, breast milk, respiratory secretions) sexual contact blood transfusion or by sharing food, drinks or eating utensils with an infected person 80 -90% of the adult population have been infected by the virus (35-40 years) It is frequently seen in individuals infected with the human immunodeficiency virus (HIV) and less often in other immunosuppressed individuals When the virus is dormant, it is hiding in an inactive form in B lymphocytes -"latent" state EBV can lead to: infection mononucleosis oral hairy leukoplakia plasmablastic lymphoma Burkitt lymphoma Hodgkin lymphoma nasopharyngeal carcinoma Kikuchi histocytic necrotizing lymphadenitis