Irmeli Lautenschlager

Chromosomally integrated human herpesvirus 6: questions and answers

Chromosomally integrated human herpesvirus 6 (ciHHV‐6) is a condition in which the complete HHV‐6 genome is integrated into the host germ line genome and is vertically transmitted in a Mendelian manner. The condition is found in less than 1% of controls in the USA and UK, but has been found at a somewhat higher prevalence in transplant recipients and other patient populations in several small studies. HHV‐6 levels in whole blood that exceed 5.5 log10 copies/ml are strongly suggestive of ciHHV‐6. Monitoring DNA load in plasma and serum is unreliable, both for identifying and for monitoring subjects with ciHHV‐6 due to cell lysis and release of cellular DNA. High HHV‐6 DNA loads associated with ciHHV‐6 can lead to erroneous diagnosis of active infection. Transplant recipients with ciHHV‐6 may be at increased risk for bacterial infection and graft rejection. ciHHV‐6 can be induced to a state of active viral replication in vitro. It is not known whether ciHHV‐6 individuals are put at clinical risk by the use of drugs that have been associated with HHV‐6 reactivation in vivo or in vitro. Nonetheless, we urge careful observation when use of such drugs is indicated in individuals known to have ciHHV‐6. Little is known about whether individuals with ciHHV‐6 develop immune tolerance for viral proteins. Further research is needed to determine the role of ciHHV‐6 in disease. Copyright

Cytomegalovirus infection and development of biliary complications after liver transplantation

Background. Cytomegalovirus (CMV) infection is known to cause ulceration and mucosal hemorrhage in the gastrointestinal tract. Gastroduodenal and biliary complications were prospectively evaluated in 100 consecutive liver transplant patients in whom CMV was monitored during the first posttransplant year. Method. Gastroduodenal biopsy specimens were taken from 36 patients by endoscopies and in 28 patients by endoscopic retrograde cholangiopancreatography, and bile duct specimens were taken from three patients who underwent surgical reconstruction because of biliary complication. CMV was demonstrated from blood by the pp65 antigenemia test and from frozen sections of tissue specimens by immunohistochemistry and in situ hybridization. Results. Symptomatic CMV infection, treated with ganciclovir, developed in 49 recipients: 13 (100%) of CMV seropositive donor (D+) seronegative recipient (R−) cases, 29 (45%) D+/R+ cases, and 7 (32%) D−/R+ cases. Duodenal ulcer developed in three and hemorrhagic gastritis in three recipients. CMV antigens were found from the gastroduodenal mucosa in 37 (69%) of the 54 studied recipients. The biliary complication rate was 24%. Preceding or concomitant CMV antigenemia was demonstrated in 75% of patients with a biliary complication (68% in CMV D+/R+ or D−/R+ and 100% in D+/R− recipients). The biliary complication rate was higher among recipients with CMV antigenemia, compared with recipients without (P <0.05). CMV antigenemia, CMV infection, or both in the duodenal mucosa was found in 96% of patients with a biliary complication. In two patients who underwent surgical reconstruction, CMV antigens and DNA were demonstrated in the bile ducts. Conclusions. Liver transplant patients are at risk of developing biliary complications after CMV infection, especially those with primary CMV infection.

Human herpesvirus-6 antigenemia after liver transplantation.

BACKGROUND Human herpesvirus (HHV)-6 has recently been reported in liver transplant patients. It infects and causes dysfunction in hepatic transplants, which provides serious differential diagnostic problems between allograft rejection and viral infection. The diagnosis of posttransplantation HHV-6 infection is usually based on serology or on polymerase chain reaction detection of viral DNA in peripheral blood specimens. However, serology does not tell the exact time of the infection, and detection of viral DNA by polymerase chain reaction may also indicate a latent infection in seropositive patients. Here we report the diagnostic use of frequent monitoring of HHV-6 antigenemia after liver transplantation. METHODS Altogether 622 blood specimens from 51 consecutive adult liver transplant patients were analyzed. The diagnosis was based on demonstration of HHV-6-specific antigens in peripheral blood mononuclear cells using immunoperoxidase staining and monoclonal antibodies and on serology. RESULTS During the first year (7-280 days) after transplantation, HHV-6 infection was diagnosed in 11 (22%) of 51 patients. HHV-6 early antigens, as well as HHV-6 variant B antigens, were detected in all 11 patients. HHV-6 diagnosis was confirmed by serology. The episode of HHV-6 antigenemia usually lasted for several weeks together with mild, if any, clinical signs of the infection. A significant graft dysfunction was associated with HHV-6 antigenemia in 8 of 11 patients, and viral antigens were also detected in the liver biopsy specimens of 3 of these patients. CONCLUSIONS An active HHV-6 infection can be diagnosed from peripheral blood by detection of virus-specific antigens in mononuclear cells. HHV-6 antigenemia correlated with seroresponse.

The inflammatory mechanisms of allograft rejection

If one wishes to describe the rejection process in biologicai terms, it may be divided into the following, largely overlapping components: (a) induction of rejection, i.e., how does the alien graft induce the antiallograft immune response, (b) the immune response towards the graft, and (c) the inflammatory response of rejection and regulation of the inflammation by the immune response. Finally one should consider (d) the effector mechanisms in situ, i.e., how do the inflammatory cells, together with the antibody, destroy the graft.

Persistent cytomegalovirus infection in kidney allografts is associated with inferior graft function and survival

The long‐term effects of cytomegalovirus (CMV) infections on kidney allografts are unknown. We examined the impact of persistent intragraft CMV infection on long‐term kidney allograft function and survival. CMV was diagnosed in 82/172 renal transplant recipients by antigenemia test and viral cultures. Biopsies from 48 of 82 patients taken after CMV infection and from 15 patients with no previous CMV infection detected were available for the immunohistochemical demonstration of CMV antigens and DNA hybridization in situ. Five‐year follow‐up data from these 63 patients were analysed. In 17 patients, CMV antigens and/or DNA persisted in the biopsy >2 months after the last positive finding in blood or urine. Patients with persistent intragraft CMV had reduced graft survival (P = 0.041) and Cox regression analysis showed persistent CMV as a risk factor for reduced graft survival (RR: 3.5). Recipients with persistent intragraft CMV had reduced creatinine clearance 1 and 2 years after transplantation (P = 0.007) and in multivariate logistic regression analyses including several potential pre‐ and posttransplant risk factors, persistent CMV was an independent risk factor for lower clearance at 1 and 2 years (OR: 4.4 and 4.9). Our novel findings show that persistent intragraft CMV infection was associated with reduced kidney allograft function and survival.

CMV infection is usually associated with concurrent HHV-6 and HHV-7 antigenemia in liver transplant patients

Human herpesvirus 6 and 7 (HHV-6, HHV-7) have been recently reported in liver transplant patients. HHV-6 may cause fever, neurological disorders and hepatitis. The clinical significance of HHV-7 is less clear. HHV-6 and -7 are closely related to cytomegalovirus (CMV), and interactions between the viruses have also been suggested. In this study, we investigated the post transplant HHV-6 and -7 antigenemia was in relation to symptomatic CMV disease after liver transplantation. Consecutive 34 adult liver allograft recipients transplanted during 1999-2000 were included in the study. CMV infections were diagnosed by the frequent monitoring of pp65-antigenemia and by viral cultures. HHV-6 and -7 were demonstrated, by using immunoperoxidase staining and monoclonal antibodies against the virus specific antigens, in the mononuclear cells from the same blood specimens which were obtained for CMV pp65 monitoring. Altogether 322 blood specimens were analyzed. CMV disease was diagnosed in 12 (35%) patients during the first 3 months (first pp65 positive specimen mean 25 days, range 8-61 days) after transplantation. Concurrent HHV-6 antigenemia was detected in 10/12 (mean 14 days, range 6-22 days) and HHV-7 antigenemia in 9/12 patients (mean 25 days, range 10-89 days) after transplantation. HHV-6 usually appeared slightly before CMV. All CMV infections were successfully treated with ganciclovir and the CMV-antigenemia subsided. HHV-6 and -7 antigenemia also responded to the antiviral treatment, but more slowly than CMV. In conclusion, CMV infection was usually associated with HHV-6 and -7 antigenemia in liver transplant patients. The results support the suggestion that CMV, HHV-6 and -7 may have interactions. The clinical symptoms of CMV infection, may also be linked with HHV-6 or -7.

Effect of cytomegalovirus on an experimental model of chronic renal allograft rejection under triple-drug treatment in the rat.

BACKGROUND Cytomegalovirus (CMV) infection is thought to be a risk factor of chronic rejection. In clinical studies and animal models, mainly concerning graft vasculopathy, CMV has been demonstrated to enhance allograft arteriosclerosis. In this study we have investigated the effect of CMV on the early inflammatory response and graft histology in an experimental model of renal transplantation in a rat strain combination that develops chronic rejection under triple-drug immunosuppression. METHODS Renal transplantations were performed in a rat strain combination of DA-->BN receiving triple-drug treatment (2 mg/kg methylprednisolone, 2 mg/kg azathioprine, 5 mg/kg cyclosporine daily subcutaneously). One group of immunosuppressed animals was infected with rat CMV, the Maastricht strain (10(5) plaque-forming units intraperitoneally), and the other group was left uninfected. As a positive control for alloresponse, one group of recipients received neither immunosuppression nor virus. Syngenic transplantations with triple-drug treatment and CMV were used as negative controls. The grafts were monitored by frequent ultrasound-guided fine-needle aspiration biopsies, and the intragraft inflammation was quantified in detail by the increment method and expressed in corrected increment units (CIU). Graft histology was performed in parallel. RESULTS Nonimmunosuppressed animals developed acute rejection with a high peak of inflammation (7.9+/-3.2 CIU), a typical blast response, and lymphocytosis followed by infiltration of macrophages and necrosis within 7 days. Triple drug-treated animals had a short, mild inflammatory response (3.3+/-1.4 CIU at the peak) in the graft 3-5 days after transplantation but ended up with histological changes characteristic of chronic rejection with vasculopathy and fibrosis 40-60 days later. Triple drug-treated animals with CMV demonstrated a significantly stronger inflammation (4.5+/-1.8 CIU, P<0.01) than those without, and lymphoid activation continued longer and was followed by infiltration of macrophages in the graft. CMV infection of the graft was demonstrated by viral culture and antigen detection. In histology, chronic rejection with intimal thickening of arteries and arterioles and medial necrosis of large arteries was seen at 14 days, ending up with remarkable graft fibrosis within 20 days after transplantation. CONCLUSION CMV prolonged and increased graft inflammation and accelerated chronic rejection of renal allografts under triple-drug treatment.

An International Multicenter Performance Analysis of Cytomegalovirus Load Tests

A new quantitative polymerase chain reaction assay, COBAS AmpliPrep/COBAS TaqMan CMV Test, was developed using the first World Health Organization cytomegalovirus standard. It demonstrated a high level of interlaboratory agreement and precision compared to quantitative results obtained with tests used by 5 different laboratories.

Human herpesvirus-6 and acute liver failure.

Background. In patients with acute liver failure (ALF) of unknown cause, viral infections are believed to be involved. This study investigates the involvement of human herpesvirus-6 (HHV-6). Methods. Thirty-two patients with ALF who underwent transplantations during a 6-year period were studied for viruses in biopsies from their explanted livers. Non-A to non-E hepatitis (unknown) ALF was the reason for transplantation in 15 patients, and another 17 patients with a known disease from the same time period served as controls. The explanted livers were examined for hepatitis viruses and other possible viral agents. HHV-6 antigens were demonstrated in the livers and blood mononuclear cells by immunoperoxidase staining. Results. Of the 15 patients with ALF of unknown cause, 12 (80%) demonstrated HHV-6 antigens in the liver. Most of these patients (10/12) also demonstrated HHV-6 antigenemia. The predominant histologic finding of HHV-6 infection was moderate to severe portal lymphocytic infiltration. HHV-6 was found in 4 of 17 control patients, and cytomegalovirus was found in 2 of 17 control patients (in the blood and explanted liver). No other viruses were found in the livers of the patients with ALF. Conclusions. HHV-6 was found in most explanted livers of patients with ALF of unknown cause. HHV-6 antigenemia was associated with HHV-6 antigens in the liver. Only a few control patients displayed HHV-6 in the liver. These observations indicate that HHV-6 may be one of the causes of ALF.

Cytomegalovirus infection-enhanced allograft arteriosclerosis is prevented by DHPG prophylaxis in the rat.

BACKGROUND Major risk factors for accelerated allograft arteriosclerosis include humoral and cellular immune response, hyperlipidemia, and viral infections. We demonstrated earlier that rat cytomegalovirus (RCMV) infection doubles smooth muscle cell proliferation and intimal thickening of rat aortic allografts. In this study, the effects of 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG) on RCMV-enhanced rat allograft arteriosclerosis are investigated. METHODS AND RESULTS Aortic allografts from the DA to the WF rat strain were used. The recipients were inoculated with 10(5) plaque-forming units of RCMV 1 day after transplantation. Two groups of RCMV-infected rats were treated with DHPG with an initial dose of 20 mg/kg IP and a maintenance dose of 10 mg/kg IP twice a day for a period of 14 days. In the DHPG prophylaxis group (n = 22), the drug administration started 1 day before infection, and in the DHPG treatment group (n = 17), 7 days after infection. One group of infected rats was left untreated (n = 21). The grafts were removed 7 and 14 days and 1, 3, and 6 months after transplantation. In the DHPG prophylaxis group, no virus could be recovered by plaque assays. In the treatment group, 50% of rats were virus-positive at 1 month and 40% at 3 months. DHPG prophylaxis prevented the infiltration of inflammatory cells and their proliferation in the adventitia of RCMV-infected recipients (P < .01), with a 60% reduction in the interleukin-2 receptor expression (P < .05) and a 30% decrease in major histocompatibility complex class II expression (P = NS). DHPG prophylaxis did not significantly alter the levels of insulin-like growth factor-1, epidermal growth factor, platelet-derived growth factor-BB, transforming growth factor-beta 1, acidic fibroblast growth factor, and basic fibroblast growth factor messages in the allograft vascular wall. Early media necrosis was reduced. Arteriosclerotic alterations and proliferation of smooth muscle cells were both reduced 50% to 70% by DHPG prophylaxis (P < .05 at 3 months). The responses in the DHPG treatment group were quite similar but less impressive and statistically nonsignificant. CONCLUSIONS We consider it likely that DHPG inhibits arteriosclerotic alterations primarily by reducing the infectious virus and thereby the inflammatory response in the allograft vascular wall; another possibility is a direct antiproliferative effect on smooth muscle cell replication. A dose-dependent inhibitory effect of DHPG on smooth muscle cell replication was recorded in an in vitro study.