Human herpesvirus type 7 in Hodgkin's disease

Changing patterns in the Epstein-Barr virus (EBV)and Hodgkin lymphoma association in Tunisia

We compared the features of the Epstein-Barr virus (EBV) and Hodgkin lymphoma (HL) association in Tunisia in two periods of time, 1991-2001 (111 cases) and 2002-2012 (122 cases). The investigation of the EBV status by EBER in situ hybridization showed a significant decrease in the prevalence of EBV-positive HL from 69.3 % for the period 1991-2001 to 40.1 % for the 2002-2012 period (p = 0.00001). EBV positivity has decreased in all age groups but was more pronounced among young patients, in the 15-24-year age group (46.1 vs 10.3 %, p = 0.003), in the 25-34-year age group (56.2 vs 25 %, p = 0.04), and among children (88.4 vs 59.2 %, p = 0.01). This decrease in EBV-positive HL over time contrasted with a remarkable increase in EBV-negative HL in young adults aged 15-34 years (51.2 vs 83 %; p = 0.001), especially among women (59.1 vs 91.2 %; p = 0.01). The decrease in EBV-positive HL over time concerns particularly the nodular sclerosis histological subtype (69.2 vs 31.6 %, p = 0.000001). These results indicate that the epidemiology of HL and its association with EBV are changing over time, with a trend toward a Western profile, and point toward the emergence of other environmental causative factors, especially among young women, which remain to be identified.

Prevalence of herpesviruses at onset of idiopathic nephrotic syndrome

BACKGROUND

Idiopathic nephrotic syndrome (INS) is likely a primary immune disorder, but viruses might also be involved in the mechanisms of the disease. Here, we investigate the link between herpesvirus infection and the first manifestation of INS in children.

METHODS

A prospective, multicentre, and population-based case-control study called NEPHROVIR included 164 patients, aged 6 months to 15 years old, newly diagnosed with INS, and 233 controls matched for gender, age, and period of sample. The analysis was done on 124 patients and 196 controls. Epstein-Barr virus (EBV), cytomegalovirus (CMV), human herpesvirus-6 (HHV-6), and human herpesvirus-7 (HHV-7) DNA prevalence at diagnosis were assessed from whole peripheral blood samples, as well as EBV and CMV viral load and seroprevalence.

RESULTS

EBV DNA was significantly more prevalent in cases than in controls (50.8 vs 29.1 %; OR = 2.6; p = 0.0002), with no difference in viral load. A significant difference was also found for CMV (11.3 vs 3.6 %; p = 0.02) and HHV-7 (83 vs 72 %; p = 0.02) DNA prevalence between cases and controls. There were significantly more EBV and CMV recent infections or reactivations based on VCA-IgM and CMV IgM in cases than controls, while there were no differences in IgG seroprevalence.

CONCLUSION

The prevalence of positive EBV DNA detection and recent infection or reactivation is higher in children at onset of INS compared to a population matched for age, gender, and time of sampling.

Polymorphisms in the Interleukin-10 and Interferon Gamma Genes in Hodgkin Lymphoma

Genetic factors are known to be important in the development of Hodgkin lymphoma (HL). Interleukin-10 (IL-10) secretion by both malignant and reactive cells is thought to be important in the pathogenesis of HL especially Epstein-Barr virus (EBV) positive cases. Polymorphisms of the IL-10 gene have been reported to be associated with susceptibility to EBV infection. The cytotoxic response to EBV is determined by a Th1 biased immune response which is characterised by interferon gamma (IFNgamma) secretion. We therefore investigated polymorphisms in the IL-10 (-1082 G/A and -592 C/A) and IFNgamma (intron 1 CA repeat) genes as predisposing factors in the development 147 cases of HL. A difference of borderline statistical significance was demonstrated for the IFNgamma gene polymorphism but significance was lost when analysis was restricted to the common genotypes. No significant differences in the distributions of genotypes were found for the IL-10 gene polymorphisms. IL-10 and IFNgamma levels were also measured on 26 patients with HL. No statistically significant differences were detected when the results were analysed by genotype. We found little evidence IL-10 and IFNgamma genotypes predispose to the development of HL or influence the inflammatory host response.

Questionable role of human herpesviruses in the pathogenesis of Kikuchi disease

CONTEXT

Kikuchi disease is a self-limiting febrile lymphadenopathy characterized by a patchy area of apoptosis. Kikuchi disease is thought to be caused by a virus, but this has not been clearly demonstrated. Human herpesviruses 6 and 7 (HHV-6 and HHV-7) are lymphotropic viruses that can induce apoptosis in infected lymphocytes. Recently, HHV-8 was reported to be a possible etiologic agent of Kikuchi disease.

OBJECTIVE

To investigate the incidence of HHV-6, HHV-7, and HHV-8 infection in patients with Kikuchi disease.

DESIGN

Seventy archival tissue specimens (from 50 Kikuchi disease cases and 20 control cases) were tested for the presence of HHV-6 and HHV-7 using a nested polymerase chain reaction, and for the presence of HHV-8 using single-step polymerase chain reaction. Immunohistochemistry for HHV-8 expression was carried out in those cases in which HHV-8 was detected using polymerase chain reaction.

RESULTS

Of the 50 cases with Kikuchi disease, 21 (42%) were HHV-6 positive and 32 (64%) were HHV-7 positive. Eight (40%) of the 20 control cases were HHV-6 positive and 9 (45%) were HHV-7 positive. Both HHV-6 and HHV-7 were detected in 15 (30%) of the cases with Kikuchi disease and in 3 (15%) of the control cases. Three (6%) of the 50 cases of Kikuchi disease were HHV-8 positive but revealed no positive cells on immunohistochemical analysis for HHV-8. Human herpesvirus 8 was not expressed in any of the control cases.

CONCLUSIONS

There was no association between the presence of HHV-6 or HHV-7 and Kikuchi disease. Because the HHV-8 genome but not protein was detected in a small proportion of the cases of Kikuchi disease, its potential causative role in this disease should be determined by further studies.

Lack of association of polyomavirus and herpesvirus types 6 and 7 in human lymphomas

BACKGROUND

The association of viruses with several human tumors has been studied for almost 100 years, and it remains a very controversial issue. Due to the fact that the presence of polyomaviruses and herpes viruses reportedly are associated with lymphomas, albeit with striking results and differences between the many studies, the authors undertook a study into the presence of viral sequences of polyomavirus (BK virus, JC virus, and especially simian virus 40 [SV40]) in human lymphomas in an attempt to explain this contradictory association. To complete the study, the presence of different virus types from the herpesviriridae family were analyzed, such as herpesvirus type 6 (HHV6), HHV7, HHV8, and Epstein-Barr virus, in human lymphomas.

METHODS

DNA was isolated from 83 frozen human lymphoma samples, and different polymerase chain reaction techniques were used to find polyomavirus and herpesvirus sequences in these samples. To assess the incidence of the presence of sequences in lymphomas, a parallel analysis was made of 53 samples from normal donor spleen lymphocytes. Positive samples were analyzed for polyomavirus sequences by immunohistochemistry.

RESULTS

Polyomavirus sequences were detected in 9 of 83 lymphomas (11%), and SV40 sequences could be confirmed in only 1 lymphoma. Immunohistochemistry for large-T antigen was negative in all samples. Herpesviruses were detected in 53 of 83 lymphomas (63.9%), were detected more frequently in Hodgkin lymphomas (80%) than in non-Hodgkin lymphomas (58.7%), and were detected in > 60% of normal spleen lymphocytes.

CONCLUSIONS

The current results did not support a clear association of polyomavirus and HHV6 or HHV7 with lymphomas; HHV6 and HHV7 sequences were detected in a similar percentage of normal samples and lymphomas. The lack of significant differences between normal and malignant lymphocytes and the absence of viral protein expression in the tumor cells did not allow the establishment of a clinical correlation between polyomaviruses or HHVs (HHV6, HHV7, HHV8) and lymphomas. Nevertheless, because viral products can be lost during tumor progression, and because host factors can modulate the oncogenic role of some viruses, the hypothetical role of these viruses cannot be discarded completely.

Viruses and Hodgkin's lymphoma

Hodgkin's lymphoma (HL) is unusual among human malignancies in that the epidemiology suggests an infectious aetiology. The Epstein-Barr virus (EBV) is associated with a proportion of cases and this association is believed to be causal. In these cases the Hodgkin and Reed-Sternberg (HRS) cells express the EBV-encoded proteins LMP1 and LMP2, which can mimic CD40 and the B cell receptor, respectively, and therefore may play a critical role in facilitating the survival of HRS cells. EBV-associated and non-EBV-associated HL cases have different epidemiological features and recent data suggest that delayed exposure to EBV is a risk factor for the development of EBV-associated HL in young adults. We suggest that HL can be divided into four entities on the basis of EBV status and age at presentation, with three groups of EBV-associated cases and a single group of EBV-negative cases. The aetiology of the latter cases is obscure although involvement of an infectious agent(s) is suspected.

Human herpesvirus 7 in dermatology: what role does it play?

Human herpesvirus 7 (HHV-7) was discovered in 1989 as a new member of the beta-herpesvirus subfamily. Primary infection occurs early in life and manifests as exanthema subitum, or other febrile illnesses mimicking measles and rubella. Thus, HHV-7 has to be considered as a causative agent in a variety of macular-papular rashes in children. In addition, HHV-7 was found in some cases of other inflammatory skin disorders, such as psoriasis. There are controversial data on the detection of HHV-7 in pityriasis rosea, but so far there is not enough evidence for a pathogenetic association of HHV-7 with this exanthematic skin disease. Although HHV-7 can be found in some cases of Hodgkin's disease, there are no data supporting a direct causative role in this lymphoma type nor in other nodal or primary cutaneous lymphomas. In various epidemiologic forms of Kaposi's sarcoma, infection of monocytic cells with HHV-7 was demonstrated, which may indirectly influence tumor biology. In the context of immunosuppression, HHV-7 has recently been identified as an emerging pathogen in transplant recipients and may exacerbate graft rejection in renal transplant recipients. The ability of HHV-7 to induce cytokine production in infected cells could make HHV-7 an important pathogenetic co-factor in inflammatory and neoplastic disorders. Moreover, the restricted cellular tropism of HHV-7 may render this virus an interesting vector for gene therapy. Thirteen years after the discovery of HHV-7, there has been considerable progress in characterizing its genetic structure, virus-induced effects on infected host cells and in the development of diagnostic tools. Nevertheless, the role of HHV-7 in various skin diseases and the clinical manifestations of reactivation of HHV-7 infection have still to be defined.

Viruses and Hodgkin disease: no evidence of novel herpesviruses in non-EBV-associated lesions

The Epstein-Barr virus (EBV) is associated with a proportion of cases of Hodgkin disease (HD) and this association is believed to be causal. Epidemiological studies suggest that an infectious agent is involved in the aetiology of young adult HD, however, cases in this age group are less likely to have EBV-associated disease than cases diagnosed in early childhood or older adult years. Molecular studies have failed to find a consistent association between HD and other candidate viruses, and the aetiology of non-EBV-associated cases remains obscure. We looked for evidence of herpesvirus infection in samples of non-EBV-associated HD using a highly sensitive, degenerate PCR assay. Despite exhaustive sequence analysis of PCR products, no novel herpesviruses were identified. These results suggest that it is extremely unlikely that a novel herpesvirus is involved in the pathogenesis of non-EBV-associated HD.

Immune reactivity of human sera to the glycoprotein B of human herpesvirus 7

The glycoprotein B (gB) is highly conserved among distinct human herpesvirus 7 (HHV-7) strains. Similarly to other herpesvirus glycoproteins, gB has been assumed to induce a specific human immune response. However, it did not appear as an immunodominant protein in conventional immunoblot assays. Recombinant gB, obtained from either Escherichia coli or baculovirus expression systems, did react specifically with HHV-7-seropositive sera, and the main corresponding epitopes were located in its N-terminal part. A 24-amino-acid peptide, corresponding to a predicted hydrophilicity peak and presenting no extensive homology with other betaherpesvirus glycoproteins, was selected in this region at positions 129 to 152 of the gB sequence. When tested by enzyme-linked immunosorbent assay (ELISA), this peptide specifically reacted with HHV-7-seropositive sera. This reactivity was significantly inhibited by the preincubation of sera with the peptide itself, lysates of gB-expressing cells, or lysates of HHV-7-infected cells. The reactivity was not significantly modified when sera were preincubated with lysates of either human cytomegalovirus (HCMV)- or HHV-6-infected cells. In cross-sectional studies including both children and adults, 49 out of 61 serum samples (80%) were found to be positive by HHV-7 ELISA, independent of their reactivity to HCMV. A longitudinal serological study of 17 children during the first 4 years of life showed that the level of ELISA-detected antibodies significantly decreased within a few weeks after birth and then increased in the following months, likely reflecting, respectively, the loss of maternal antibodies and the occurrence of seroconversion. These results demonstrate that gB peptide ELISA might be a useful tool for the serological study of HHV-7 infection.

Lymphomatoid papulosis and human herpesviruses--A PCR-based evaluation for the presence of human herpesvirus 6, 7 and 8 related herpesviruses

BACKGROUND

Lymphomatoid papulosis (LyP) is a chronic, recurrent lymphoproliferative disorder of the skin that belongs to the group of primary cutaneous CD30-positive T-cell lymphomas. Ultrastructural and clinical features of LyP suggest that it has a viral etiology. Human herpesviruses have been proposed as causative cofactors for LyP because of their oncogenic potential and their association with other lymphomas.

METHODS

LyP skin lesions and a LyP-derived cell line were examined for the presence of the recently discovered oncogenic human herpesvirus 8 (HHV-8) and the two T-lymphotropic human herpesviruses 6 and 7 (HHV-6 and HHV-7) by nested polymerase chain reaction (PCR) using virus-specific oligonucleotide primers. Furthermore, a recently described method involving degenerate PCR primers was applied to detect highly conserved DNA sequences shared by a variety of herpesviruses, especially oncogenic gamma-herpesviruses, in an attempt to identify a yet undiscovered herpesvirus associated with LyP.

RESULTS

HHV-6 and 8 could not be found in 26 archival and 11 snap-frozen LyP lesions and a LyP tumor cell line. HHV-7 DNA sequences were detected in 14% (5 of 37) of LyP samples. HHV-6 was found in 23% (3 of 13) and HHV-7 in 8% (1 of 13) of normal skin samples from healthy individuals, respectively. Using degenerate PCR primers to amplify the highly conserved polymerase region of herpesviruses, no DNA sequences related to human herpesviruses could be detected.

CONCLUSIONS

LyP is not associated with HHV-6, HHV-7 and HHV-8. In addition, the studies using degenerate PCR primers do not indicate the presence of a previously undescribed human herpesvirus in LyP.

Detection of Epstein-Barr virus and human herpesvirus 7 and 8 genomes in primary cutaneous T- and B-cell lymphomas

BACKGROUND

Several studies have investigated the possible involvement of viral agents, particularly herpesviruses, in primary cutaneous lymphoma (PCL).

OBJECTIVES

Our aim was to screen for the presence of human herpesvirus 7 (HHV-7) and 8 (HHV-8) genomes in samples of PCL, and to determine if their presence was independent of Epstein-Barr virus (EBV).

METHODS

Screening was performed using polymerase chain reaction assay in 64 skin samples from historical lesional tissues with PCL.

RESULTS

Only nine cases showed positivity for HHV-7: four of 29 mycosis fungoides (MF), two of four CD30-positive large-cell cutaneous T-cell lymphoma (CTCL), two of 12 follicle centre cutaneous B-cell lymphoma (CBCL) and one of nine marginal zone CBCL. Fifteen cases tested positive for EBV: seven of 29 MF, two of four pleomorphic small/medium sized CTCL, three of three angiocentric CTCL, one of 12 follicle centre CBCL and two of nine marginal zone CBCL. All cases were uniformly negative for HHV-8. No simultaneous positivity was found for EBV and HHV-7. Controls tested negative for all viruses.

CONCLUSIONS

The findings indicate that EBV, HHV-7 and HHV-8 seem not to be involved in the pathogenesis of PCL.

Human herpesviruses in primary ocular lymphoma

Several human lymphotropic herpesviruses have been found in certain lymphoproliferative disorders and implicated as possible etiologic factors or as modulating elements of the diseases. To assess a possible association of the human herpesviruses with lymphomas arising from mucosa-associated lymphoid tissue (MALT), we evaluated the presence of four human herpesviruses, Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), HHV-7, and HHV-8, in the biopsied specimens from 14 patients with primary ocular MALT lymphomas. EBV DNA sequences were detected in four specimens by polymerase chain reaction (PCR), and four cases were positive for HHV-6 DNA. In situ hybridization showed that three and two of 14 cases were positive for EBV mRNA and HHV-6 DNA, respectively. Neither HHV-7 nor HHV-8 sequences could be detected by PCR. These findings would stimulate further investigation as to the involvement of these lymphotropic viruses in the pathogenesis of a subset of low-grade primary ocular lymphomas.

Preferential associations of alleles of three distinct genes argue for the existence of two prototype variants of human herpesvirus 7

We had previously described six distinct alleles of the glycoprotein B (gB) gene of human herpesvirus 7 (HHV-7). The genetic changes corresponding to these alleles did not affect gB gene transcription or translation in in vitro assays. The study of distinct HHV-7-positive human samples showed preferential associations of some gB alleles with some alleles of two other genes, distantly located on the HHV-7 genome, coding for the phosphoprotein p100 (p100) and the major capsid protein (MCP). Two allele combinations, corresponding to 44 and 31% of the samples studied, respectively, were interpreted as the genetic signatures of two major prototype HHV-7 variants.

Human herpesvirus 7

Human herpesvirus 7, reported in 1990 is a lymphotropic member of the betaherpesvirus subfamily of herpesviruses. The virus is highly seroprevalent, primary infection usually occurs during childhood, and it has been associated with cases of exanthem subitum, pityriasis rosea, neurological manifestations and transplant complications. The latter two may warrant antiviral intervention, in vitro studies have shown that HHV-7 is susceptible to several nucleoside phosphonate compounds. In vitro, the virus has approximately a 5 day growth cycle in cultured lymphocytes; in vivo, latency is established in peripheral blood T-cells and a persistent infection is established in salivary gland tissue from which infectious virus is constitutively shed in saliva. The HHV-7 genome is approximately 145 kb and encodes at least 84 different proteins. Studies characterising HHV-7 gene products and the required interactions between viral and cellular genes necessary for virus replication, persistence and latency are in their infancy. HHV-7 infection has a variety of effects on host cells including upregulation of interleukin 15 and down-modulation of the cell surface molecule CD4; the latter serves as the cellular membrane receptor for HHV-7. Since HIV also infects T-cells via the CD4 molecule, the interactions of these viruses within T-cells during the course of AIDS are important areas of investigation.

Hodgkin's disease and non-Hodgkin's lymphoma

The development of new classification schemes and prognostic analyses for lymphomas has helped to identify patients at high risk for relapse who may benefit from intensification of primary therapy. Conventional salvage therapy for relapsed follicular or low-grade lymphomas now includes monoclonal antibody therapy. The combination of chemotherapy and monoclonal antibody therapy may improve outcomes for patients with advanced-stage aggressive non-Hodgkin's lymphomas. Confirmatory randomized trials are now in progress. Therapy for Hodgkin's disease continues to evolve toward the most efficacious programs, which also minimize the long-term probability of toxicity. The combination of high-dose chemotherapy and stem cell transplantation is probably the most effective therapy for patients with relapsed or refractory Hodgkin's disease.