Luca Ceccherini-Nelli

Torquetenovirus viremia kinetics after autologous stem cell transplantation are predictable and may serve as a surrogate marker of functional immune reconstitution

BACKGROUND It is common experience that retreating patients too early after a course of intensive chemotherapy predisposes to opportunistic infections despite apparently normal lymphocyte levels. OBJECTIVES The extent of replication of persistent viruses that cause no obvious disease (and hence need no treatment) might better define when a patient has recovered from functional immune deficiency. STUDY DESIGN We used real-time polymerase chain reaction to monitor the kinetics of plasma torquetenovirus (TTV) viremia in hematological patients undergoing autologous hematopoietic stem cell transplantation as support to high-dose chemotherapy (HSCT). RESULTS Independently from underlying hematological disease and therapeutic regimen, TTV viremia increased post-HSCT, and this increase paralleled the increase of circulating CD8(+)CD57(+) T lymphocytes, known to represent an indirect marker of functional immune deficiency. Subsequently, within a matter of months, TTV levels returned to baseline values, at a pace that appeared to be constant over time. CONCLUSION Monitoring of TTV viremia represents a unique opportunity to follow functional immune reconstitution in immunosuppressed patients. Also, the size of the TTV viremia increases resulting from immunosuppressive treatments might be of guidance in determining the appropriate time interval before delivery of a next course of therapy.

Simple in vitro methods for titrating Feline Immunodeficiency Virus (FIV) and FIV neutralizing antibodies

The feline immunodeficiency virus (FIV) readily produced syncytia in Crandell feline kidney (CrFK) cells adapted to a medium containing 0.5% fetal calf serum, a variety of growth factors and other supplements. This finding has been exploited to develop simple and sensitive virus titration and neutralization assays. High titre neutralizing antibodies were detected in cats infected naturally and experimentally with FIV, but not in uninfected animals.

Frequency and Distribution of Herpesvirus-like DNA Sequences (KSHV) in Different Stages of Classic Kaposi's Sarcoma and in Normal Tissues from an Italian Population

The frequency and distribution of herpesvirus‐like DNA sequences (KSHV) were investigated by PCR in the pathologic skin lesions of a series of 22 HIV‐negative elderly patients with classic Kaposis sarcoma (KS) from Italy, one of the few regions of the world where classic KS is prevalent. Viral sequences were clearly identifiable in 15 cases, in particular in 2 of 5 patch, in 3 of 6 plaque and in 10 of 11 nodular lesions. Our findings confirm the association of these herpesvirus‐like DNA sequences with KS in unrelated populations, providing evidence of the putative KS‐associated agent in all different histologic lesions of the disease, mainly in the nodular stage. The search for other herpesviruses by PCR showed that Epstein‐Barr virus (EBV) sequences were present in 7 of 22 pathologic skin lesions. In 4 cases, both EBV and KSHV were present. On the contrary, all 22 classic KS specimens were negative for human herpesvirus‐6 sequences. Two of 3 patch and the 1 nodular lesions from AIDS‐related KS patients examined were positive for KSHV but negative for both EBV and HHV‐6 sequences. Furthermore, we evaluated the prevalence of KSHV sequences in the normal population of the same geographical area. Thirteen peripheral blood mononuclear cell samples, 9 salivary gland tissues and 6 saliva samples from healthy subjects were invariably found negative for KSHV, using the same PCR technique. Of interest, 2 of 11 hyperplastic tonsils harboured these herpesvirus‐like sequences, suggesting that, like other herpesviruses, the KS‐associated agent may be harboured in a proportion of normal individuals and tonsils may represent at least one of the possible reservoirs of this putative lymphotropic γ‐herpesvirus in vivo.

Torquetenovirus DNA drives proinflammatory cytokines production and secretion by immune cells via toll-like receptor 9

Active infection with torquetenovirus (TTV) has been associated with an increased severity of diseases in which inflammation plays a particularly important pathogenetic role. Here, we report that cloned DNA of a genogroup 4 TTV (ViPiSAL) is an activator of proinflammatory cytokine production by murine spleen cells and that the effect is mediated via toll-like receptor (TLR)9. The same DNA also increased the levels of proinflammatory cytokines induced by two well-characterized TLR9 stimulants. Finally, in silico analyses of the genomes of ViPiSAL and other TTVs revealed marked differences in the representation of CpG motifs known to be most effective at activating immune cells via TLR9. These findings demonstrate for the first time that at least one TTV isolate has the potential to stimulate and co-stimulate inflammatory responses.

Reactivation of human herpesvirus 6 (HHV-6) infection in patients with connective tissue diseases

BACKGROUND Little is known about the involvement of human herpesviruses 6 and 7 (HHV-6 and HHV-7) in autoimmune connective tissue diseases (ACTD). OBJECTIVE To determine the prevalence of active infection with HHV-6 and HHV-7 in patients with ACTD. STUDY DESIGN The presence and quantity of HHV-6 DNA was determined by quantitative real-time PCR in a cross-sectional study of serum, peripheral blood mononuclear cells, and tissues obtained from 58 ACTD patients and 38 healthy subjects (HS). Specific anti-HHV-6 antibody titer was also measured. RESULTS HHV-6 serum viremia occurred in a significantly higher proportion of ACTD patients compared to HS [26/58 (44.8%) vs. 1/38 (2.6%), p=0.001] with the highest reactivation frequency [7/10 (70%)] observed in patients with scleroderma. Moreover, HHV-6 in serum was associated with ACTD activity (22/38 vs. 4/20, p<0.05). Higher titers of HHV-6 antibodies were found in ACTD patients than in HS, although HHV-6 seroprevalence among patients with ACTD and HS was similar. HHV-7 viremia was not detected in any patients or HS controls. CONCLUSION The frequent reactivation of HHV-6 in scleroderma and other ACTD, especially when active, suggests that HHV-6 may play a role in the pathogenesis of these diseases.

Possible Role of Human Herpesvirus 6 as a Trigger of Autoimmune Disease

Human herpesvirus 6 (HHV-6) infection is common and has a worldwide distribution. Recently, HHV-6A and HHV-6B have been reclassified into two distinct species based on different biological features (genetic, antigenic, and cell tropism) and disease associations. A role for HHV-6A/B has been proposed in several autoimmune disorders (AD), including multiple sclerosis (MS), autoimmune connective tissue diseases, and Hashimotos thyroiditis. The focus of this review is to discuss the above-mentioned AD associated with HHV-6 and the mechanisms proposed for HHV-6A/B-induced autoimmunity. HHV-6A/B could trigger autoimmunity by exposing high amounts of normally sequestered cell antigens, through lysis of infected cells. Another potential trigger is represented by molecular mimicry, with the synthesis of viral proteins that resemble cellular molecules, as a mechanism of immune escape. The virus could also induce aberrant expression of histocompatibility molecules thereby promoting the presentation of autoantigens. CD46-HHV-6A/B interaction is a new attractive mechanism proposed: HHV-6A/B (especially HHV-6A) could participate in neuroinflammation in the context of MS by promoting inflammatory processes through CD46 binding. Although HHV-6A/B has the ability to trigger all the above-mentioned mechanisms, more studies are required to fully elucidate the possible role of HHV-6A/B as a trigger of AD.

Role of Hematopoietic Cells in the Maintenance of Chronic Human Torquetenovirus Plasma Viremia

ABSTRACT Many aspects of the life cycle of torquetenoviruses (TTVs) are essentially unexplored. In particular, it is still a matter of speculation which cell type(s) replicates the viruses and maintains the generally high viral loads found in the blood of infected hosts. In this study, we sequentially measured the TTV loads in the plasma of four TTV-positive leukemia patients who were strongly myelosuppressed and then transplanted with haploidentical hematopoietic stem cells. The findings provide clear quantitative evidence for an extremely important role of hematopoietic cells in the maintenance of TTV viremia.

Selective reactivation of human herpesvirus 6 in patients with autoimmune connective tissue diseases

Viral infections have been associated with autoimmune connective tissue diseases. To evaluate whether active infection by Epstein–Barr virus (EBV), cytomegalovirus (CMV), human herpesvirus (HHV)‐6, ‐7, ‐8, as well as parvovirus B19 (B19V) occur in patients with autoimmune connective tissue diseases, viral DNA loads were assessed in paired samples of serum and peripheral blood mononuclear cells (PBMCs) of 115 patients affected by different disorders, including systemic sclerosis, systemic, and discoid lupus erythematosus, rheumatoid arthritis, and dermatomyositis. Two additional groups, patients affected by inflammatory diseases (n = 51) and healthy subjects (n = 58) were studied as controls. The titers of anti‐HHV‐6 and anti‐EBV antibodies were also evaluated. Cell‐free HHV‐6 serum viremia was detected in a significantly higher proportion of connective tissue diseases patients compared to controls (P < 0.0002); a significant association between HHV‐6 reactivation and the active disease state was found only for lupus erythematosus (P = 0.021). By contrast, the rate of cell‐free EBV viremia was similar in patients and controls groups. Cell‐free CMV, HHV‐8, and B19V viremia was not detected in any subject. Anti‐HHV‐6 and anti‐EBV early antigen IgG titers were both significantly higher in autoimmune diseases patients as compared to healthy controls, although they were not associated with the presence of viremia. EBV, HHV‐6, ‐7 prevalence and viral load in PBMCs of patients with connective tissue diseases and controls were similar. These data suggest that HHV‐6 may act as a pathogenic factor predisposing patients to the development of autoimmune connective tissue diseases or, conversely, that these disorders may predispose patients to HHV‐6 reactivation. J Med. Virol. 85:1925–1934, 2013.

Hyperbaric oxygen therapy in BKV-associated hemorrhagic cystitis refractory to intravenous and intravesical cidofovir: Case report and review of literature

Hemorrhagic cystitis is a common complication in hematopoietic stem cell transplant recipients. We report here a case of severe BKV-associated hemorrhagic cystitis who did not respond to intravenous cidofovir. Overt hematuria successfully resolved after a few days on hyperbaric oxygen and intravesical instillations of cidofovir, while BK viruria dropped after a few weeks and remained low. We review the literature for therapeutic options in hemorrhagic cystitis and try to explain how hyperbaric oxygen stimulates mucosal repair in the urinary bladder.

Progressive Multifocal Leukoencephalopathy: What’s New?

Progressive multifocal leukoencephalopathy (PML), a severe demyelinating disease that is caused by human JC polyomavirus, was first described as a complication of immune suppression 50 years ago and emerged as a major complication of HIV infection in the 1980s. The prognosis has remained dismal since then, with discouraging results from clinical trials of various therapeutic approaches, including immunomodulation and/or inhibition of viral replication. PML is caused by reactivation of latent JC virus, and serotonergic 5-HT2a receptors have been identified as being critical for viral infection of glial cells. In recent years, immunosuppressive therapeutic antibodies have been associated with an increased incidence rate of PML. Here, the authors review findings on the pathogenesis of PML and the encouraging case reports of novel treatments.