Asymptomatic Viremia Research Articles

Cytomegalovirus Infection in a Seroendemic Renal Transplant Population: A Longitudinal Study of Virological Markers

Background/Aims: The detection of viremia by polymerase chain reaction (PCR) in cytomegalovirus (CMV) infection in renal allograft recipients has been shown to have a predictive value for disease. However, its diagnostic utility in a population with high background seropositivity has not been defined. This prospective study was undertaken to assess the relationship of CMV DNAemia, and/or IgM seropositivity to CMV disease in a seroendemic transplant population. Methods: Consecutive patients undergoing renal transplantation between August 1997 and February 1998 were enrolled. Blood was sampled before transplantation from the donors and recipients for CMV serology and nested PCR for CMV DNA, and after transplantation from the recipients only at monthly intervals until 6 months. Patients were observed for the development of any CMV-like illness during follow-up. CMV DNA was quantitated using limiting dilution PCR on samples obtained from symptomatic patients at the time of illness and from asymptomatic patients at the end of their 6-month follow-up. Results: A total of 57 recipient-donor pairs were recruited. Immunosuppression was cyclosporine-based in 55 of 57 (95.6%). The CMV serologic status was D+R+ in 55 of 57 and D+R– in 2 of 57 pairs. PCR positivity indicating viremia increased from 5% before transplantation to 95% at 6 months after transplantation. Similarly IgM positivity reached 80% at 3 months and thereafter; positivity for any marker was 100% by 6 months. Viremia was sustained in over half the patients. The incidence of CMV-attributable disease peaked at 3 months, and was predominantly mild and self-limiting. Tissue-invasive disease appeared later in 4 patients (7%). Asymptomatic viremia was seen in 60–70% of patients at each sampling point. The positive predictive value (PPV) of PCR positivity for disease was 35–40%, and the negative predictive value (NPV), 90–100%. However, the high NPV was of use only in the early post-transplant period, negativity for markers declining rapidly with time. Quantitative assay showed significantly higher levels of CMV DNA in symptomatic patients (p = 0.01). A cutoff of 0.001 µg had a specificity of 95% and a PPV of 92.3% for symptomatic CMV disease. Conclusion: Qualitative tests to detect CMV DNAemia and IgM, although useful markers of viremia and active infection, have limited utility for the diagnosis of disease in a seroendemic transplant population. Quantitation of CMV DNAemia may play an important role in diagnosis in such a setting.

Response of asymptomatic cytomegalovirus viraemia to oral ganciclovir 3 g/day or 6 g/day in HIV‐infected patients

Reactivation of cytomegalovirus (CMV) following immunosuppression may result in the development of CMV disease and is associated with an increased risk of death. CMV viraemia detected by the polymerase chain reaction (PCR) precedes CMV disease in HIV-infected patients and identifies individuals at high risk of disease. Pre-emptive ganciclovir (GCV) therapy in patients who have evidence of CMV viraemia is effective in preventing disease. An open study was conducted to assess the response of CMV viraemia to oral GCV at a dose of 3 or 6 g/day for 28 days. HIV RNA was measured to determine if CMV inhibition affected HIV viral load. Fourteen patients were studied, three of whom entered both phases of the study. None of the patients had evidence of CMV disease at the time of entry into the trial; two patients developed CMV retinitis after completion of the trial. Oral GCV at both 3 and 6 g/day caused a decrease in CMV viral load in individual patients. However, a rebound in CMV viral load occurred in patients receiving the 3-g/day dose. None of the patients receiving oral GCV 3 g/day became PCR negative after 21 days compared with six of eight patients receiving 6 g/day. Five of eight patients (63%) receiving GCV 6 g/day were concurrently taking protease inhibitors compared with two of nine (22%) receiving 3 g/day. Ten patients remained PCR negative throughout follow up. No change was found in HIV viral load during receipt of GCV at either dose. Thus, oral GCV is effective in reducing CMV viral load, but a dose of 3 g/day is insufficiently potent for pre-emptive therapy. J. Med. Virol. 59:323–328, 1999. © 1999 Wiley-Liss, Inc.

Response of asymptomatic cytomegalovirus viraemia to oral ganciclovir 3 g/day or 6 g/day in HIV-infected patients

Reactivation of cytomegalovirus (CMV) following immunosuppression may result in the development of CMV disease and is associated with an increased risk of death. CMV viraemia detected by the polymerase chain reaction (PCR) precedes CMV disease in HIV-infected patients and identifies individuals at high risk of disease. Pre-emptive ganciclovir (GCV) therapy in patients who have evidence of CMV viraemia is effective in preventing disease. An open study was conducted to assess the response of CMV viraemia to oral GCV at a dose of 3 or 6 g/day for 28 days. HIV RNA was measured to determine if CMV inhibition affected HIV viral load. Fourteen patients were studied, three of whom entered both phases of the study. None of the patients had evidence of CMV disease at the time of entry into the trial; two patients developed CMV retinitis after completion of the trial. Oral GCV at both 3 and 6 g/day caused a decrease in CMV viral load in individual patients. However, a rebound in CMV viral load occurred in patients receiving the 3-g/day dose. None of the patients receiving oral GCV 3 g/day became PCR negative after 21 days compared with six of eight patients receiving 6 g/day. Five of eight patients (63%) receiving GCV 6 g/day were concurrently taking protease inhibitors compared with two of nine (22%) receiving 3 g/day. Ten patients remained PCR negative throughout follow up. No change was found in HIV viral load during receipt of GCV at either dose. Thus, oral GCV is effective in reducing CMV viral load, but a dose of 3 g/day is insufficiently potent for pre-emptive therapy.

INCREASED PREOPERATIVE QUASISPECIES DIVERSITY MAY BE PREDICTIVE OF LONG-TERM OUTCOME AFTER ORTHOTOPIC LIVER TRANSPLANTATION FOR HEPATITIS C VIRUS

277 Purpose: Recurrence of hepatitis C virus (HCV), the leading indication for orthotopic liver transplantation (OLT), accounts for a significant proportion of graft dysfunction. At present, predicting recurrence is difficult. Viral factors may be predictive of outcome. Therefore, we correlated HCV amino acid sequence diversity at the first hypervariable region (HVR1) of the second envelope protein (E2) with long-term outcome. Methods: Twenty-four patients with HCV-induced end-stage liver disease who underwent liver transplantation between 10/95 to 12/98 were prospectively evaluated. Recurrence of significant hepatitis was defined by pathology and biochemical parameters. Twelve representative patients underwent detailed pre- and post-operative serum quasispecies analysis by nucleotide sequencing the HVR1 of cloned PCR products. Results: A summary of results is below (mean ± SEM): (Table)TableMean follow up was 612±25 days. All patients had viremia within 2 months after OLT. Biochemical recurrence occurred at 169±55 days. There was no difference between groups in ischemic time, HLA matching, donor and recipient age, HCV quantity, use of CSA or FK506, gender, or CMV status. One death occurred (17%, P=NS) in the recurrent hepatitis group. Eighty-three percent of patients with asymptomatic viremia had a predominant major variant (accounting for >50% of clones) compared to 17% in those with recurrence (P<0.025). In summary, patients with significant recurrent hepatitis had a greater preoperative diversity of HCV quasispecies in the HVR1 that did not persist in the post-operative period. Conclusions: Increased HCV quasispecies diversity may be predictive of recurrent HCV-induced hepatitis after OLT for HCV. This diversity did not persist postoperatively.

Prevention and treatment of cytomegalovirus infection and disease in heart transplant recipients.

Despite advances in prophylaxis and treatment, cytomegalovirus (CMV) infection remains a significant problem in the solid-organ transplant recipient. In addition to the clinical manifestations of CMV infection, there is also the immunosuppressive effect of CMV, which confers increased risk for fungal and other opportunistic infections. In reference to heart transplant recipients, the possible connection between CMV infection and rejection or CMV infection and allograft vasculopathy are areas of active research. Recent diagnostic advances, such as the CMV antigenemia assay and CMV-DNA detection by polymerase chain reaction or direct hybrid capture, have enabled early detection and monitoring of CMV infection and have raised the question of the implications of asymptomatic viremia. A wide variety of prophylactic strategies have been evaluated in heart and other solid-organ transplant recipients, including antiviral agents, globulin preparations, combinations of these therapies, and pre-emptive treatment strategies based on early detection or identification of a high-risk subset of patients. Many of these regimens have demonstrated efficacy in certain groups of patients, but a consensus has yet to emerge in terms of a single preferable strategy. Future advances on the horizon include the development of newer antiviral agents and a vaccine.

A Sequential Histologic and Immunohistochemical Study of Duck Hepatitis B Virus Infection in Pekin Ducks

Twenty-nine Pekin ducks were inoculated with duck hepatitis B virus (DHBV), DHBV-free serum, or saline at 1 day of age. Congenitally DHBV-infected ducks were also studied. Ducks were killed periodically during a 92-week study and examined histologically and immunohistochemically to assess liver and extrahepatic inflammation and to detect and characterize DHBV core antigen tissue distribution. DHBV infection produced an asymptomatic but persistent DHBV viremia in all ducks associated with a mild to moderate transient hepatic inflammation apparent at 3 to 6 weeks post-inoculation and waning afterwards. DHBV core antigen was detected in hepatocyte cytoplasm at 1 week post-inoculation, and by 3 weeks post-inoculation scattered pancreatic acinar and islet cells also contained viral antigen. Small numbers of mononuclear cells in the splenic white pulp also contained viral antigen. Viral antigen persisted in all of these tissues throughout the duration of the experiment. No inflammation or tissue injury was detected in any of the extrahepatic tissues during the course of DHBV infection. One DHBV-injected duck developed a hepatocellular carcinoma at 88 weeks of age. Isolated patches of neoplastic hepatocytes contained cytoplasmic DHBV core antigen. The results of this study indicate that DHBV, like mammalian hepadnavirus, is capable of producing a persistent infection of the liver and several extrahepatic tissues and suggest that persistent infection may be associated with the development of hepatocellular carcinoma.

Experimental Transmission and Pathogenesis of Immunodeficiency Syndrome in Cats

We describe the identification, experimental transmission, and pathogenesis of a naturally occurring powerfully immunosuppressive isolate of feline leukemia virus (designated here as FeLV-FAIDS) which induces fatal acquired immunodeficiency syndrome (AIDS) in 100% (25 of 25) of persistently viremic experimentally infected specific pathogen-free (SPF) cats after predictable survival periods ranging from less than 3 months (acute immunodeficiency syndrome) to greater than one year (chronic immunodeficiency syndrome), depending on the age of the cat at time of virus exposure. The pathogenesis of FeLV-FAIDS-induced feline immunodeficiency disease is characterized by: a prodromal period of largely asymptomatic viremia; progressive weight loss, lymphoid hyperplasia associated with viral replication in lymphoid follicles, lymphoid depletion associated with extinction of viral replication in lymphoid follicles, intractable diarrhea associated with necrosis of intestinal crypt epithelium, lymphopenia, suppressed lymphocyte blastogenesis, impaired cutaneous allograft rejection, hypogammaglobulinemia, and opportunistic infections such as bacterial respiratory disease and necrotizing stomatitis. The clinical onset of immunodeficiency syndrome correlates with the replication of a specific FeLV-FAIDS viral variant, detected principally as unintegrated viral DNA, in bone marrow, lymphoid tissues, and intestine. Two of seven cats with chronic immunodeficiency disease that survived greater than 1 year after inoculation developed lymphoma affecting the marrow, intestine, spleen, and mesenteric nodes. Experimentally induced feline immunodeficiency syndrome, therefore, is a rapid and consistent in vivo model for prospective studies of the viral genetic determinants, pathogenesis, prevention, and therapy of retrovirus-induced immunodeficiency disease.

Experimental transmission and pathogenesis of immunodeficiency syndrome in cats

We describe the identification, experimental transmission, and pathogenesis of a naturally occurring powerfully immunosuppressive isolate of feline leukemia virus (designated here as FeLV-FAIDS) which induces fatal acquired immunodeficiency syndrome (AIDS) in 100% (25 of 25) of persistently viremic experimentally infected specific pathogen- free (SPF) cats after predictable survival periods ranging from less than 3 months (acute immunodeficiency syndrome) to greater than one year (chronic immunodeficiency syndrome), depending on the age of the cat at time of virus exposure. The pathogenesis of FeLV-FAIDS-induced feline immunodeficiency disease is characterized by: a prodromal period of largely asymptomatic viremia; progressive weight loss, lymphoid hyperplasia associated with viral replication in lymphoid follicles, lymphoid depletion associated with extinction of viral replication in lymphoid follicles, intractable diarrhea associated with necrosis of intestinal crypt epithelium, lymphopenia, suppressed lymphocyte blastogenesis, impaired cutaneous allograft rejection, hypogammaglobulinemia, and opportunistic infections such as bacterial respiratory disease and necrotizing stomatitis. The clinical onset of immunodeficiency syndrome correlates with the replication of a specific FeLV-FAIDS viral variant, detected principally as unintegrated viral DNA, in bone marrow, lymphoid tissues, and intestine. Two of seven cats with chronic immunodeficiency disease that survived greater than 1 year after inoculation developed lymphoma affecting the marrow, intestine, spleen, and mesenteric nodes. Experimentally induced feline immunodeficiency syndrome, therefore, is a rapid and consistent in vivo model for prospective studies of the viral genetic determinants, pathogenesis, prevention, and therapy of retrovirus-induced immunodeficiency disease.