Efficacy and safety of extended duration letermovir prophylaxis in recipients of haematopoietic stem-cell transplantation at risk of cytomegalovirus infection: a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

In a pivotal phase 3 trial of cytomegalovirus prophylaxis with letermovir for up to 100 days after allogeneic haematopoietic stem-cell transplantation (HSCT), 12% of participants developed clinically significant cytomegalovirus infection after letermovir was discontinued. We aimed to evaluate the efficacy and safety of extending the duration of letermovir prophylaxis for clinically significant cytomegalovirus infection from 100 days to 200 days following HSCT.

METHODS

We conducted a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial at 32 sites in six countries (France, Germany, Italy, Japan, the UK, and the USA). Cytomegalovirus‑seropositive HSCT recipients (aged ≥18 years) who had received letermovir prophylaxis for up to 100 days following HSCT and who remained at high risk of late clinically significant cytomegalovirus infection (with no previous history of clinically significant cytomegalovirus infection, defined as initiation of pre-emptive therapy for documented cytomegalovirus viraemia, onset of cytomegalovirus end-organ disease, or both) were eligible. Participants were randomly assigned (2:1) to receive either an additional 100 days (ie, a total of 200 days; letermovir group) of oral or intravenous letermovir 480 mg once daily, adjusted to 240 mg once daily for participants on cyclosporin A, or 100 days of a placebo comparator for letermovir (ie, a total of 100 days of letermovir; placebo group), following HSCT. Randomisation was done using a central interactive response technology system, stratified by study centre and haploidentical donor (yes or no). Participants, investigators, and sponsor personnel were masked to the treatment allocation. The primary efficacy endpoint was the proportion of participants from randomisation to week 28 (200 days after HSCT) with clinically significant cytomegalovirus infection, analysed using the full analysis set population (ie, those who received at least one dose of study intervention). Safety was analysed in all participants as treated (ie, those who received at least one dose according to the study intervention they were assigned to). This study is registered with ClinicalTrials.gov, NCT03930615, and is complete.

FINDINGS

Between June 21, 2019, and March 16, 2022, 255 patients were screened for eligibility and 220 (86%) were randomly assigned (145 [66%] in the letermovir group and 75 [34%] in the placebo group). Between randomisation and week 28, four (3%) of 144 participants in the letermovir group and 14 (19%) of 74 in the placebo group developed clinically significant cytomegalovirus infection (treatment difference -16·1% [95% CI -25·8 to -6·5]; p=0·0005). The most common adverse events among participants in the letermovir group versus the placebo group were graft-versus-host disease (43 [30%] vs 23 [31%]), diarrhoea (17 [12%] vs nine [12%]), nausea (16 [11%] vs 13 [18%]), pyrexia (13 [9%] vs nine [12%]), and decreased appetite (six [4%] vs nine [12%]). The most frequently reported serious adverse events were recurrent acute myeloid leukaemia (six [4%] vs none) and pneumonia (three [2%] vs two [3%]). No deaths were considered to be drug-related by the investigator.

INTERPRETATION

Extending the duration of letermovir prophylaxis to 200 days following HSCT is efficacious and safe in reducing the incidence of late clinically significant cytomegalovirus infection in patients at risk.

FUNDING

Merck Sharp & Dohme LLC.

Maribavir: Mechanism of action, clinical, and translational science

Maribavir is an oral benzimidazole riboside for treatment of post-transplant cytomegalovirus (CMV) infection/disease that is refractory to prior antiviral treatment (with or without resistance). Through competitive inhibition of adenosine triphosphate, maribavir prevents the phosphorylation actions of UL97 to inhibit CMV DNA replication, encapsidation, and nuclear egress. Maribavir is active against CMV strains with viral DNA polymerase mutations that confer resistance to other CMV antivirals. After oral administration, maribavir is rapidly and highly absorbed (fraction absorbed >90%). The approved dose of 400 mg twice daily (b.i.d.) achieves a steady-state area under the curve per dosing interval of 128 h*μg/mL and trough concentration of 4.90 μg/mL (13.0 μM). Maribavir is highly bound to human plasma proteins (98%) with a small apparent volume of distribution of 27.3 L. Maribavir is primarily cleared by hepatic CYP3A4 metabolism; its major metabolite, VP44669 (pharmacologically inactive), is excreted in the urine and feces. There is no clinically relevant impact on maribavir pharmacokinetics by age, sex, race/ethnicity, body weight, transplant type, or hepatic/renal impairment status. In phase II dose-ranging studies, maribavir showed similar rates of CMV viral clearance across 400, 800, or 1200 mg b.i.d. groups, ranging from 62.5-70% in study 202 (NCT01611974) and 74-83% in study 203 (EudraCT 2010-024247-32). In the phase III SOLSTICE trial (NCT02931539), maribavir 400 mg b.i.d. demonstrated superior CMV viremia clearance at week 8 versus investigator-assigned treatments, with lower treatment discontinuation rates. Dysgeusia, nausea, vomiting, and diarrhea were commonly experienced adverse events among patients treated with maribavir in clinical trials.

Ocrelizumab-induced colitis and cytomegalovirus infection and their disadvantageous interaction with underlying multiple sclerosis

Ocrelizumab is a humanized monoclonal antibody against the B-lymphocyte antigen CD20 and the only approved treatment option in primary progressive multiple sclerosis. Herpesvirus-related infections like cytomegalovirus (CMV) infections are common in patients receiving ocrelizumab, whereas gastrointestinal side effects with inflammatory bowel disease (IBD) like esophagitis or colitis are very rare. This case report describes the challenging clinical, endoscopic, and histologic features of an ocrelizumab-induced colitis overlapping with CMV infection and their disadvantageous interaction with the underlying multiple sclerosis.

Effects of Induction Therapy on Graft Functions in Terms of Immunologic Risk

BACKGROUND

Advances in immunosuppressive therapies and surgical techniques have led to a significant reduction in the incidence of rejection within 1 year after kidney transplantation. Immunologic risk is an important factor affecting graft functions and guiding the clinician in the selection of induction therapy. The aim of this study was to investigate graft functions based on serum creatinine levels, Chronic Kidney Disease Epidemiology Collaboration (CKD- EPI) and proteinuria levels, frequency of leukopenia, cytomegalovirus (CMV) and BK virus polymerase chain reaction (PCR) positivity in patients with low and high immunologic risk.

MATERIAL AND METHODS

This retrospective study included 80 renal recipients. Recipients were divided into 2 groups: patients at low immunologic risk who received basiliximab only and those with high immunologic risk who received low-dose (1.5 mg/kg for 3 days) antithymocyte globulin and basiliximab.

RESULTS

No significant differences were observed between the 2 risk groups in terms of first, third, sixth, and 12th-month creatinine levels, CKD-EPI, proteinuria levels, leukopenia frequency, and CMV and BK virus PCR positivity.

CONCLUSION

One-year graft survivals did not differ significantly between these 2 treatment modalities. The combined use of low-dose antithymocyte globulin and basiliximab in the induction treatment of patients with high immunologic risk seems promising in terms of graft survival, leukopenia frequency, and CMV and BK virus PCR positivity.

Case Report: Cytomegalovirus Reactivation and Pericarditis Following ChAdOx1 nCoV-19 Vaccination Against SARS-CoV-2

As the coronavirus disease 2019 (COVID-19) pandemic is ongoing and new variants of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) are emerging, there is an urgent need for vaccines to protect individuals at high risk for complications and to potentially control disease outbreaks by herd immunity. Surveillance of rare safety issues related to these vaccines is progressing, since more granular data emerge about adverse events of SARS-CoV-2 vaccines during post-marketing surveillance. Varicella zoster virus (VZV), Epstein-Barr virus (EBV) and cytomegalovirus (CMV) reactivation has already been reported in COVID-19 patients. In addition, adverse events after SARS-CoV-2 mRNA vaccination have also been in the context of varicella zoster virus (VZV) reactivation and directly associated with the mRNA vaccine. We present the first case of CMV reactivation and pericarditis in temporal association with SARS-CoV-2 vaccination, particularly adenovirus-based DNA vector vaccine ChAdOx1 nCoV-19 against SARS-CoV-2. After initiation of antiviral therapy with oral valganciclovir, CMV viremia disappeared and clinical symptoms rapidly improved. Since huge vaccination programs are ongoing worldwide, post-marketing surveillance systems must be in place to assess vaccine safety that is important for the detection of any events. In the context of the hundreds of millions of individuals to be vaccinated against SARS-CoV-2, a potential causal association with CMV reactivation may result in a considerable number of cases with potentially severe complications.

Posttransplant cyclophosphamide is associated with increased cytomegalovirus infection: a CIBMTR analysis

Prior studies suggest increased cytomegalovirus (CMV) infection after haploidentical donor transplantation with posttransplant cyclophosphamide (HaploCy). The role of allograft source and posttransplant cyclophosphamide (PTCy) in CMV infection is unclear. We analyzed the effect of graft source and PTCy on incidence of CMV infection, and effects of serostatus and CMV infection on transplant outcomes. We examined patients reported to the Center for International Blood and Marrow Transplantation Research between 2012 and 2017 who had received HaploCy (n = 757), matched related (Sib) with PTCy (SibCy, n = 403), or Sib with calcineurin inhibitor-based prophylaxis (SibCNI, n = 1605). Cumulative incidences of CMV infection by day 180 were 42%, 37%, and 23%, respectively (P < .001). CMV disease was statistically comparable. CMV infection risk was highest for CMV-seropositive recipients (R+), but significantly higher in PTCy recipients regardless of donor (HaploCy [n = 545]: hazard ratio [HR], 50.3; SibCy [n = 279]: HR, 47.7; SibCNI [n = 1065]: HR, 24.4; P < .001). D+/R- patients also had increased risk for CMV infection. Among R+ or those developing CMV infection, HaploCy had worse overall survival and nonrelapse mortality. Relapse was unaffected by CMV infection or serostatus. PTCy was associated with lower chronic graft-versus-host disease (GVHD) overall, but CMV infection in PTCy recipients was associated with higher chronic GVHD (P = .006). PTCy, regardless of donor, is associated with higher incidence of CMV infection, augmenting the risk of seropositivity. Additionally, CMV infection may negate the chronic GVHD protection of PTCy. This study supports aggressive prevention strategies in all receiving PTCy.

Tacrolimus trough levels higher than 6 ng/mL might not be required after a year in stable kidney transplant recipients

Background

Little is known regarding optimal tacrolimus (TAC) trough levels after 1 year post-transplant in stable kidney transplant recipients (KTRs) who have not experienced renal or cardiovascular outcomes. This study aimed to investigate the effect of 1-year post-transplant TAC trough levels on long-term renal and cardiovascular outcomes and opportunistic infections in stable KTRs.

Methods

KTRs receiving TAC with mycophenolate-based immunosuppression who did not experience renal or cardiovascular outcomes within 1 year post-transplant were enrolled from a multicenter observational cohort study. Renal outcome was defined as a composite of biopsy-proven acute rejection, interstitial fibrosis and tubular atrophy, and death-censored graft loss. Cardiovascular outcome was defined as a composite of de novo cardiomegaly, left ventricular hypertrophy, and cardiovascular events. Opportunistic infections were defined as the occurrence of BK virus or cytomegalovirus infections.

Results

A total of 603 eligible KTRs were divided into the low-level TAC (LL-TAC) and high-level TAC (HL-TAC) groups based on a median TAC level of 5.9 ng/mL (range 1.3–14.3) at 1 year post-transplant. The HL-TAC group had significantly higher TAC trough levels at 2, 3, 4, and 5 years compared with the levels of the LL-TAC group. During the mean follow-up of 63.7 ± 13.0 months, there were 121 renal outcomes and 224 cardiovascular outcomes. In multivariate Cox regression analysis, LL-TAC and HL-TAC were not independent risk factors for renal and cardiovascular outcomes, respectively. No significant differences in the development of opportunistic infections and de novo donor-specific anti-human leukocyte antigen antibodies and renal allograft function were observed between the two groups.

Conclusions

TAC trough levels after 1 year post-transplant remained at a similar level until the fifth year after kidney transplantation and were not directly associated with long-term outcomes in stable Korean KTRs who did not experience renal or cardiovascular outcomes. Therefore, in Asian KTRs with a stable clinical course, TAC trough levels higher than approximately 6 ng/mL might not be required after a year of kidney transplantation.

Cytomegalovirus Hemorrhagic Cystitis in a Malignant Glioma Patient Treated with Temozolomide

Temozolomide, a key drug in the treatment of malignant glioma, can cause profound lymphopenia and various opportunistic infectious diseases. A 79-year-old woman with anaplastic oligodendroglioma developed a fever and gross hematuria after 8 weeks of standard radiotherapy with concomitant temozolomide treatment. A cytomegalovirus (CMV) antigen test for pp65 antigenemia was positive (137 cells per 75,800 leukocytes), and the findings from a urine cytology test were consistent with CMV-induced hemorrhagic cystitis. She was treated with ganciclovir, and her condition improved. CMV monitoring is needed when patients develop symptoms related to opportunistic infections during temozolomide treatment for malignant glioma.

[Thymoma with immunodeficiency/Good syndrome associated with myasthenia gravis]

Good syndrome is a rare condition in which thymoma is associated with hypogammaglobulinemia; it is characterized by repeated respiratory or systemic infections caused by bacteria, viruses, and fungi, as well as with various autoimmune disorders such as pure red cell aplasia. A 65-year-old woman was admitted to our hospital with ptosis and abdominal muscle weakness. Based on the presence of anti-acetylcholine receptor (Ach-R) antibodies, she was diagnosed with myasthenia gravis (MG). At that time, invasive thymoma of Masaoka stage IVa was also detected. Regression of thymoma and clinical remission of MG was achieved by chemotherapy followed by high-dose corticosteroid. However, several months later, the patient started developing repeated bacterial respiratory tract infections, cytomegalovirus infections, and esophageal and systemic candidiasis. Laboratory tests revealed a marked decrease of serum gamma-globulin levels (IgG 586 mg/dl, IgA 32 mg/dl, IgM 29 mg/dl) and severe reduction in the B cells ratio, as well as a decrease in the CD4+CD25+T cell to CD4+CD25-T cell ratio indicative of deregulation of CD4+T cell activation. These results suggested that the patient impaired humoral and cell-mediated immune responses. We continued the treatment with antibiotics and regular immunoglobulin supplementation through intravenous injections. Although autoimmune disorders are often observed in Good syndrome, the association with MG is quite rare. The case report is followed by the review of literature.

Catastrophic gastrointestinal complication of systemic immunosuppression

We present a case of acute upper gastrointestinal haemorrhage in a patient with systemic vasculitis immunosuppressed on cyclophosphamide and prednisolone. The patient presented with a diffuse haemorrhagic oesophagitis and a non-specific duodenitis. Biopsies taken from the oesophagus and duodenum demonstrated infection with herpes simplex virus (HSV) and cytomegalovirus (CMV) respectively. Viral infection of the upper gastrointestinal tract is a recognised complication of immunosuppression and HSV is one of the most common pathogens. CMV on the other hand most commonly causes a colitis or less commonly oesophagitis. CMV enteritis is rare as is the synchronous infection with two viral agents in an immunocompromised patient having being described in a few case series only. Viral infection of the gastrointestinal tract in immunocompromised patients should be treated with systemic anti-viral medication and consideration to withdrawal of the immunosuppressive therapy if possible and appropriate. The authors highlight the need for a high suspicion of viral infection in immunosuppressed patients presenting with upper gastrointestinal bleeding.

[Development of cytomegalovirus antigenemia in 3 patients with B cell lymphoma treated with bendamustine monotherapy]

Bendamustine is one of the new key drugs for patients with indolent lymphoma. Bendamustine, together with rituximab, significantly improves the treatment outcomes of these patients. In addition, previous clinical studies have shown the complication rate of severe infection in bendamustine-containing regimens to be relatively low as compared to those of conventional chemotherapeutic regimens such as CHOP. However, some clinical case reports have raised the possibility that bendamustine may abrogate the immune responses of patients and trigger opportunistic infections including cytomegalovirus reactivation. Herein, we report three indolent lymphoma cases becoming positive on cytomegalovirus antigenemia assay during bendamustine monotherapy. All events occurred after more than three courses of treatment with bendamustine. One patient showed decreased CD4 positive T lymphocytes before the development of cytomegalovirus antigenemia. All three patients were successfully treated with valganciclovir. Although the precise risk is unknown, it should be noted that bendamustine can potentially cause reactivation of/infection with cytomegalovirus and physicians should pay attention to the possibility of this infection during treatment with bendamustine-containing regimens.

Cytomegalovirus esophagitis precipitated with immunosuppression in elderly giant cell arteritis patients

Cytomegalovirus (CMV) infection is generally associated with significant immunosuppression. Cellular immunity is particularly important and corticosteroid treatment increases the risk of CMV infection substantially. Immunocompetence generally decreases with age, older patients are at higher risk for developing CMV disease than are younger patients. CMV infection in the immunocompetent adults is quite rare. Esophagitis is the second most common gastrointestinal manifestation of CMV infection after colitis. Herein, we present three cases of giant cell arteritis who developed CMV esophagitis after various periods of corticosteroid treatment. CMV infection should be included in the differential diagnosis of GI disease in immunocompromised patients, and the clinician should pursue appropriate diagnostic and therapeutic interventions aggressively.

Management of cytomegalovirus infection in a patient with malignant glioma treated with temozolomide and steroids

Temozolomide (TMZ) is the standard chemotherapy treatment for glioblastoma. Lymphocytopenia is reported to be the most frequent and severe adverse effect of TMZ and leads to opportunistic infections. Few cases of TMZ-induced cytomegalovirus (CMV) reactivation have so far been reported, and there are no guidelines regarding the use of chemotherapy after recovery from CMV reactivation. We herein report the case of a 45-year-old man with glioblastoma who developed CMV hepatitis following surgery and chemoradiotherapy with concomitant TMZ and steroids. After successful treatment of the CMV infection with an antiviral agent and recovery from the lymphocytopenia were achieved, the patient resumed maintenance therapy with TMZ under careful monitoring of his lymphocyte count and CMV pp65 antigenemia level.

Case report: severe CMV colitis in a patient with follicular lymphoma after chemotherapy

BACKGROUND

Cytomegalovirus (CMV) can infect immuno-compromised host, especially in HIV and bone marrow transplantation patients. CMV colitis was reported after receiving chemotherapy in a solid tumor and aggressive Non-Hodgkin's lymphoma, but not yet in indolent lymphoma patients.

CASE REPORT

In the present report, a 64-year-old woman was re-admitted with watery diarrhea after eight cycles of chemotherapy for Follicular lymphoma. She had hyponatremia, hypokalemia, and hypocalcemia, which were the consequences of severe diarrhea. After two weeks of continuous diarrhea, she was set for colonoscopy, which showed multiple ulcers along the colon. Pathological results were found to be consistent with CMV colitis. Her diarrhea symptom improved after receiving ganciclovir.

CONCLUSION

CMV colitis could occur in indolent lymphoma patients who receive R-CVP regimen (rituximab, cyclophosphamide, vincristine, and prednisolone). Patients exhibiting severe and prolonged diarrhea should be investigated for definite diagnosis in order to receive proper treatment.

[Clinical study of pulmonary infection in kidney transplantation recipients taking new immunosuppressant]

OBJECTIVE

To explore the etiopathogenesis, therapy and incidence of pulmonary infection in kidney transplantation recipients taking new immunosuppressant.

METHODS

The clinical data from 752 kidney transplant recipients were retrospectively analyzed, who were divided into 3 groups according to the immunosuppressants administered, namely group A (CsA+MMF+Pred, n=226), group B (FK506+MMF+Pred, n=386) and group C (FK506+Rap+Pred, n=140). The incidence and mortality of pulmonary infection were recorded and the analysis of etiopathogenesis, diagnosis and therapy of pulmonary infection were carried out in the 3 groups.

RESULTS

Fifty-three patients acquired post-transplant pulmonary infection. The incidence of pulmonary infection was 7.08% (16/226) in group A, 7.25% (28/386) in group B and 6.43% (9/140) in group C. One patient died in group A and 2 in group B. Among the 53 patients, 24 had simple bacterial infection, 9 had cytomegalovirus infection, 1 had mycotic infection, 17 had combined infection, and 2 had unidentified pathogen infection. Of the pathogenic bacteria detected, 68.35% were Gram-negative.

CONCLUSION

Gram-negative bacteria are most likely responsible for pulmonary infection after kidney transplantation, which most possibly occurs within 6 months after kidney transplantation. Early diagnosis and early treatment are critical for decreasing the mortality of severe pneumonia and for improving the survival rate of the patients and grafts.

Rituximab-related viral infections in lymphoma patients

Recently, a human/mouse chimeric monoclonal antibody, rituximab, has been successfully used to treat cases of B-cell non-Hodgkin's lymphoma and some autoimmune diseases. However, several viral infections related to rituximab have been reported in the literature, but were not well characterized. To further investigate this topic, relevant English language studies were identified through Medline. There were 64 previously reported cases of serious viral infection after rituximab treatment. The median age of the cases was 61 years (range: 21 - 79). The median time period from the start of rituximab treatment to viral infection diagnosis was 5.0 months (range: 1 - 20). The most frequently experienced viral infections were hepatitis B virus (HBV) (39.1%, n = 25), cytomegalovirus infection (CMV) (23.4%, n = 15), varicella-zoster virus (VZV) (9.4%, n = 6), and others (28.1%, n = 18). Of the patients with HBV infections, 13 (52.0%) died due to hepatic failure. Among the 39 cases that had viral infections other than HBV, 13 died due to these specific infections. In this study, about 50% of the rituximab-related HBV infections resulted in death, whereas this was the case in only 33% of the cases with other infections. Close monitoring for viral infection, particularly HBV and CMV, in patients treated with rituximab should be recommended.

Cytomegalovirus reactivation after low-dose steroid treatment for hemolytic anemia in a patient with primary Epstein-Barr virus infection

Cytomegalovirus reactivation is a well described event occurring after intensive therapeutic suppression of the immune function in patients with latent infection. Treatment protocols for suppression of the immune response often include high-dose steroids. However, it is not known whether even a low-dose steroid treatment can reactivate latent cytomegalovirus in otherwise healthy persons. We documented cytomegalovirus reactivation after low-dose steroid treatment for autoimmune hemolytic anemia as a complication of Epstein-Barr virus mononucleosis in an immunocompetent 21-year-old man.

Regular virologic surveillance showed very frequent cytomegalovirus reactivation in patients treated with alemtuzumab

Ten patients with refractory lymphomas or autoimmune cytopenias were treated with alemtuzumab, and monitored prospectively for cytomegalovirus (CMV) reactivation by antigenemia and polymerase chain reaction. All patients showed virologic CMV reactivation. Two patients developed pneumonitis and hepatitis respectively, necessitating alemtuzumab withdrawal. Eight patients were asymptomatic, and with pre-emptive anti-CMV treatment, alemtuzumab therapy was uninterrupted. All patients ultimately achieved virologic remission. The frequent CMV reactivation was due to a high background seropositivity rate for CMV, severely immunocompromized patients, a sensitive detection method, and the diligence of surveillance. Frequent monitoring for and early treatment of CMV reactivation is necessary during alemtuzumab therapy.

Limited predictive value of real-time quantitative PCR cytomegalovirus monitoring in the blood. Fatal CMV pneumonia in an autologous stem cell transplant recipient previously treated with alemtuzumab

BACKGROUND

Patients treated with alemtuzumab are at very high risk for cytomegalovirus (CMV) reactivation. Also, in those who develop reactivation short time before stem cell transplantation the risk of fatal complications is extremely high.

CASE REPORT

We describe a 21-year-old patient with anaplastic large T-cell lymphoma who developed CMV reactivation after alemtuzumab treatment and received high-dose chemotherapy with autologous stein cell transplantation for progressive disease and severe bone marrow aplasia. Blood samples of the patient were tested regularly for CMV reactivation with real-time quantitative PCR. Even though it is considered the most sensitive available method it did not allow us to predict in advance development of fatal CMV pneumonia in this patient.

CONCLUSIONS

The case report illustrates limitations of prognostic value of quantitative real-time PCR CMV assessment in blood samples.

Distinct EBV and CMV reactivation patterns following antibody-based immunosuppressive regimens in patients with severe aplastic anemia

The natural history of EBV and CMV reactivation and the potential for serious complications following antibody-based immunosuppressive treatment for bone marrow failure syndromes in the absence of transplantation is not known. We monitored blood for EBV and CMV reactivation by polymerase chain reaction (PCR) weekly in 78 consecutive patients (total of 99 immunosuppressive courses) with aplastic anemia. Four regimens were studied: (1) HC, horse ATG/cyclosporine; (2) HCS, horse ATG/CsA/sirolimus; (3) RC, rabbit ATG/CsA; and (4) CP, alemtuzumab. There were no cases of EBV or CMV disease, but EBV reactivation occurred in 82 (87%) of 94 and CMV reactivation in 19 (33%) of 57 seropositive patients after starting immunosuppression. The median peak EBV copies were higher in the RC group when compared with HC, HCS, and alemtuzumab (P < .001). The median duration of PCR positivity for EBV was higher in the RC group compared with HC, HCS, and alemtuzumab (P = .001). Subclinical reactivation of both EBV and CMV is common and nearly always self-limited in patients with bone marrow failure receiving immunosuppression; different regimens are associated with different intensity of immunosuppression as measured by viral load and lymphocyte count; and viral reactivation patterns differ according to immunosuppressive regimens.

Does mycophenolate mofetil increase the risk of cytomegalovirus infection in solid organ transplant recipients?: A mini-review

Mycophenolate mofetil (MMF) is currently used for prophylaxis of acute rejection in solid organ transplantation. There have been diverging reports regarding an association between MMF and the risk of cytomegalovirus (CMV) infection. We reviewed the main published studies in an attempt to clarify the association between the use of MMF and the risk, frequency and severity of CMV infections. In a search of the Medline database with the terms "mycophenolate" and "cytomegalovir*", 42 articles were found to be relevant; among these, 29 articles were thoroughly analyzed. The first studies on MMF in renal transplantation already showed a tendency towards an association between this drug and the occurrence of CMV disease. Further studies were designed specifically to study this association; with the conclusion that an immunosuppressive regimen containing MMF increases the likelihood of CMV disease. Most studies were performed with kidney transplant recipients. We conclude that the use of MMF apparently increases the incidence of CMV disease in renal transplant patients; however, further studies are needed to confirm this association.

Does mycophenolate mofetil increase the incidence of cytomegalovirus disease compared with azathioprine after cadaveric kidney transplantation?

Although most of the published papers had not found increase in the incidence of CMV disease in kidney transplant recipients treated with mycophenolate mofetil (MMF), we had feeling from everyday practice that after its introduction number of patients with CMV disease has increased. To test this hypothesis, we performed retrospective analysis of our database, comparing the incidence of CMV disease in patients treated with azathioprine (AZA) and patients treated with MMF. CMV disease was defined as CMV antigenemia (positive CMV pp65 determined by ELISA test) plus any of the following: decrease leucocytes or platelets, increased transaminases, increase in serum creatinine. The azathioprine treated group (AZA group) included 280 patients (132 female) treated for 17,672 months with AZA + Cyclosporine A (CyA) + steroid, or AZA + steroid, while the MMF group included 219 patients (112 female) treated for 5079 months with MMF + CyA + steroid, or MMF + steroid. There was no difference in acute rejection episodes between the AZA and the MMF group. The AZA group had 51 CMV disease episodes (1 episode per 346.5 treatment months), and the MMF group experienced 43 episodes (1 per 118.1 months) (P < .01). Mean onset of CMV disease was 32.65 +/- 47.69 (SD) months after transplantation in the AZA group, and 3.72 +/- 4.43 in the MMF group. There was no difference between two treatment groups regarding the donor-recipient CMV status mismatch. Despite having the increased incidence of CMV disease, MMF group had less severe disease compared to AZA group with decrease in leukocyte count in 11.6% vs 15.7% of episodes, decrease in platelet count in 20.9% vs 21.6%, elevation of transaminases in 18.6% vs 29.4% respectively, and finally increase in serum creatinine greater than 20% in 51.2% in MMF vs 74.5% in AZA group. Five patients from the AZA group experienced CMV pneumonitis with the mortality rate of 80%. Only one patient from the MMF group had CMV pneumonitis, and he survived. According to our results, patients treated with MMF have increased risk for development of CMV disease. However, the disease course is less severe, and less frequently accompanied with deterioration of renal function in comparison to the AZA group.

Severe cytomegalovirus enterocolitis after standard chemotherapy for non-Hodgkin's lymphoma

Reports of cytomegalovirus (CMV) colitis mainly concern patients with immunocompromisation resulting from, among others, HIV infection, allogeneic bone marrow transplantation and solid organ transplantation. CMV colitis rarely occurs during standard chemotherapy for non-Hodgkin's lymphoma (NHL). An unusual case of CMV enterocolitis in a 62-year-old patient is reported. After a first course of salvage chemotherapy for NHL, diffuse erosions and sloughing mucosa were seen throughout the large bowel. The final diagnosis was based on histological findings. Although ganciclovir and foscarnet are effective for CMV viremia, their use in the treatment of severe diarrhea in our patient did not result in improvement for one week, whereas concomitant use of octreotide led to rapid improvement. Octreotide may therefore be an effective agent for severe colitis.

Risk for cytomegalovirus infection following reduced intensity allogeneic stem cell transplantation

Preliminary data suggest a faster immune recovery following non-myeloablative stem cell transplantation because of the persistence of recipient T cells, but the real impact on post-transplant infectious complications remains unknown. We retrospectively analysed the incidence of cytomegalovirus (CMV) infection in twenty patients following reduced intensity conditioning with busulfan/fludarabine+/-thiotepa and post-transplant immunosuppression with cyclosporine A/mycophenolate mofetil. Results were compared with 20 patients receiving myeloablative transplants during the same time period and who were matched for CMV risk group and for donor origin. The cumulative incidence of CMV infection following reduced intensity vs. myeloablative transplants was 60.4% vs. 40.0%, respectively (p value 0.1, log rank test). The risk for CMV infection in both cohorts was increased after in vivo T cell depletion with antithymocyte globulin (75% and 60%, respectively). Acute GVHD preceded the diagnosis of CMV infection by a median of 25 (range, 9-61) days following reduced intensity transplants and a median of 14 (range, 10-34) days in myeloablative transplants. Recurrent CMV infections were observed only in patients receiving reduced intensity transplants. Using multivariate analysis only reduced intensity transplantation and in vivo T cell depletion had a significant impact on the risk of CMV infection. In our series the incidence for CMV infection following reduced intensity transplants seems to be increased as compared with risk-matched myeloablative transplants. When adding anti-T cell antibodies to the conditioning regimen, the risk for CMV infection increases by up to 75%. Thorough studies of the risk of post-transplant viral infection are necessary to optimize surveillance as well as pre-emptive and/or prophylactic treatment strategies in the non-myeloablative transplantation setting.

Cytomegalovirus-specific CD4+ and CD8+ T-cells follow a similar reconstitution pattern after allogeneic stem cell transplantation

Cytomegalovirus (CMV) is a common herpes virus that can cause significant morbidity and mortality in immunocompromised individuals, particularly those undergoing allogeneic stem cell transplantation (SCT) for hematological malignancies. Recent studies have examined the kinetics of CMV-specific CD8+ T-cell reconstitution after SCT transplantation and have found virus-specific cytotoxic T-lymphocyte regeneration to be dependent on CMV serologic status and CMV reactivation events. However, the reconstitution kinetics of CMV-specific CD4+ T-cells under these same circumstances were not addressed. In this study, we used HLA class I peptide tetramer for CMV pp65 and cytokine flow cytometry to follow the reconstitution of both CD4+ and CD8+ CMV-specific T-cells after allogeneic SCT. We found that following SCT in which both donors and recipients are CMV seropositive, virus-specific CD4+ T-helper cells show the same reconstitution kinetics as CD8+ cytotoxic T-cells. Following CMV reactivation, a synchronous but temporary increase in both CD4+ and CD8+ CMV-specific lymphocytes occurs. The pattern repeats itself after subsequent episodes of CMV reactivation. These data imply that both CD4+ and CD8+ lymphocytes are necessary for an efficient immune response to CMV and suggest that CD4+ and CD8+ CMV-specific T-cells are required for the complete restoration of CMV immunity. These findings may have important implications in the development of CMV-specific adoptive immunotherapy strategies.

Anti-CD40 therapy extends renal allograft survival in rhesus macaques

BACKGROUND

Organ transplant recipients currently require lifetime immunosuppressive therapy, with its accompanying side effects. Biological agents that block T-cell costimulatory pathways are important components of strategies being developed to induce transplantation tolerance. The aim of this study was to test the effect of a novel chimeric anti-human CD40 monoclonal antibody (Chi 220), either alone or in combination with CTLA4-Ig, on the survival of renal allografts in a nonhuman primate model.

METHODS

Captive-bred adolescent male rhesus monkeys (Macaca mulatta) (4-10 kg) were used as recipients and donors. Four treatment protocols were tested: Chi220 monotherapy, CTLA4-Ig monotherapy, Chi220 combined with CTLA4-Ig, and H106 (anti-CD40L) combined with CTLA4-Ig. Control animals received human albumin. Recipients were followed for survival, renal allograft function as determined by measurement of serum blood urea nitrogen (BUN) and creatinine, chemistries (sodium, potassium, chloride, and bicarbonate), complete blood cell count (CBC) with differential, and the development of donor-specific alloantibody.

RESULTS

Treatment with Chi220 for 14 days prolonged renal allograft survival (MST 38.5 vs. 7 days in untreated controls). Notably, simultaneous blockade of the CD28/B7 pathway did not further augment graft survival but did suppress the development of donor-specific antibodies, an effect not achieved with Chi220 alone, despite peripheral B cell depletion. Finally, treatment with Chi220 suppressed the primary immune response to cytomegalovirus, resulting in severe systemic manifestations.

CONCLUSIONS

Blockade of the CD40 pathway with anti-CD40 mAb is immunosuppressive in a large animal, preclinical renal transplant model. The potential effect of this therapy on viral immune responses will be important to consider for the design of safe clinical trials.

High incidence of cytomegalovirus infection after nonmyeloablative stem cell transplantation: potential role of Campath-1H in delaying immune reconstitution

Nonmyeloablative conditioning is increasingly used for transplantation in a wide range of diseases, but little is known about its impact on the incidence of infections and immune reconstitution. We examined the pattern and outcome of cytomegalovirus (CMV) infections monitored by polymerase chain reaction-based assays and treated preemptively in 101 patients following nonmyeloablative conditioning containing in vivo Campath-1H. Fifty-one patients (50%) had a CMV infection at a median of 27 days after transplantation with a probability of 84.8% in patients at risk of CMV infection. The probability of recurrence of CMV infection before and after 100 days was 53.6% and 46.6%, respectively, and was more common in unrelated donor transplant recipients. All 3 patients who developed CMV disease died of this complication. The 2 patients with late CMV disease had grade III to IV graft-versus-host-disease (GVHD), which occurred de novo in only 4% of patients and in another 10% following donor lymphocyte infusions. The median time to CD4(+) T-cell count more than 200/microL was 9 months in the 48 patients studied. The probabilities of overall survival and nonrelapse mortality at 18 months were 65% and 27.8%, respectively, with no significant difference in survival between CMV-infected and -uninfected patients. The use of Campath-1H appeared to be associated with a low incidence of GVHD but a high incidence of CMV infections and prolonged immune paresis.

Increased risk of complicated CMV infection with the use of mycophenolate mofetil in allogeneic stem cell transplantation

Mycophenolate mofetil (MMF) is increasingly used for prophylaxis and therapy of GVHD in allogeneic stem cell transplantation. In some recent reports of use of MMF in solid organ transplantation a high incidence of CMV disease has been described. We evaluated the frequency and course of active CMV infection in patients who received MMF compared to those who did not receive MMF after allogeneic stem cell transplantation. We retrospectively analyzed 48 adult patients who consecutively underwent unmanipulated allogeneic bone marrow (n = 15) or peripheral stem cell transplantation (n = 33) from HLA-compatible family donors (n = 30) or unrelated donors (n = 18) from February 1997 to September 2000 at our institution. Only patients who were evaluable for the first 100 days were included in this analysis. Sixteen patients received MMF post transplant (MMF+). CMV-antigenemia was monitored by CMV-pp65 antigen. CMV-antigenemia occurred in 14 patients and was virtually only observed in CMV-IgG+ recipients (13/23, 56%). CMV-IgG+/MMF+ patients developed a higher incidence of CMV-antigenemia (8/9, 89%) compared to the CMV-IgG+/MMF- patients (5/14, 35%; P < 0.05). Moreover, five of six patients with persistent or recurrent CMV-antigenemia received MMF. No patient in either group developed CMV disease or died of CMV-related complications. In multivariate analysis including MMF treatment, unrelated vs related donor, GVHD, CMV-serostatus of the donor and stem cell graft type, only MMF treatment was found to be a significant risk factor for both overall and complicated CMV infection.

No cytomegalovirus-related deaths after non-ablative stem cell allografts

Cytomegalovirus (CMV)-related deaths and data of clinically evident CMV disease were assessed in a group of 47 individuals given allogeneic non-myeloablative hematopoietic stem cell transplants (NST). IgG anti-CMV antibodies were found in 56% of the donors and 76% of the receptors. Prophylactic ganciclovir was given to only 12 of the recipients during 100 days after the graft. There were no CMV-related deaths and clinically overt CMV disease was not found in any individual. The follow up post-transplant period of the patients, ranges between 30 and 810 days (median 242 days), the actuarial median survival (SV) is above 810 days and has not been reached, whereas the 810-days SV is 60%. Eighteen patients (38%) died 30-480 days after the transplant; four failed to engraft and died because of progressive disease; three died as a consequence of graft versus host disease (GVHD), whereas eleven individuals had a relapse of the malignancy and died. It is possible that the reduced bone marrow damage during NST, the prompt recovery of both the hematopoiesis and immune function in this type of allografts and the use of peripheral blood hematopoietic stem cell (HSC) is responsible for the absence of CMV-related deaths and clinical disease despite a high prevalence of CMV infection in these individuals.

Unusual viral infections (progressive multifocal leukoencephalopathy and cytomegalovirus disease) after high-dose chemotherapy with autologous blood stem cell rescue and peritransplantation rituximab

Efforts to reduce relapse of non-Hodgkin lymphoma after autologous transplantation have included ex vivo stem cell selection and/or peritransplantation immunotherapy. The late infectious and immunologic consequences of these maneuvers are not well understood, although an increase in early cytomegaloviral disease after CD34(+) stem cell selection and an alteration in immunoglobulin and T-cell recovery after peritransplantation rituximab has been noted. We report the first 2 cases of progressive multifocal leukoencephalopathy caused by JC papovavirus after autologous peripheral blood stem cell transplantation and a case each of cytomegalovirus retinitis and pneumonitis. All 4 patients experienced significant impairment of CD4 T-cell recovery, placing them at risk for these unusual viral infections. The clustering of cases is concerning because all occurred shortly after the introduction of peritransplantation rituximab into treatment protocols (4 of 62 immunotherapy recipients compared with 0 of 276 without; z = 3.595; P <.001), although a direct association with this CD20 B-cell-directed therapy remains speculative.

Orthotopic liver transplantation using low-dose tacrolimus and sirolimus

Although sirolimus (SRL) binds the immunophilin FK506-binding protein-12 (FKBP-12) with greater avidity than tacrolimus (TAC), animal studies have shown that SRL and TAC act synergistically to prevent rejection. Dose-related toxicity is more often the cause of TAC discontinuation than rejection. We hypothesized that SRL would allow for a substantial reduction in the concomitant dose of TAC after liver transplantation to levels less than the threshold for toxicity. A series of 56 liver transplant recipients were administered a combination of SRL and TAC (target trough levels, 7 and 5 ng/mL, respectively). Planned weaning of steroids commenced after 3 months. Pharmacokinetic (PK) studies were undertaken. Patient and graft survival were 52 patients (93%) and 51 grafts (91%), with a follow-up of 23 months (range, 6 to 35 months). One episode (1.8%) of hepatic artery thrombosis was seen. The rate of acute cellular rejection was 14%. No extra treatment was administered in 3 of 8 patients, and the other 5 episodes responded to a single course of steroids. Cytomegalovirus infection occurred in 4 patients (7%). Renal function, glucose control, and lipid metabolism are near normal in 47 patients (84%) without additional medication. Steroid elimination is completed in 51 patients (91%). Bioavailability of SRL and TAC varied between transplant recipients, but trough levels strongly correlated with the area under the curve (r(2) = 0.82 and r(2) = 0.84, respectively). Simultaneous administration did not affect the PK profile of the drugs at this dose. The ratio of trough level to daily dose correlated between SRL and TAC. The synergistic effect seen in animal models also occurs in clinical liver transplant recipients on SRL-TAC combination immunosuppression. A low-dose combination of SRL and TAC should be compared with conventional immunosuppression in a multicenter, randomized, controlled trial.

Valacyclovir for the prevention of cytomegalovirus infection after allogeneic stem cell transplantation: a single institution retrospective cohort analysis

A retrospective single center study was performed to evaluate the safety and efficacy of valacyclovir for prevention of cytomegalovirus (CMV) infection (reactivation) after allogeneic stem cell transplantation (SCT). We compared a group of 31 patients at risk for CMV reactivation (donor, recipient or both seropositive for CMV) who received valacyclovir at an oral dose of 1 g three times a day for CMV prophylaxis with a matched cohort of 31 patients who did not receive the drug or any other form of CMV prophylaxis. Valacyclovir was used as primary prophylaxis in 12 patients and as secondary prophylaxis (after a prior CMV reactivation was effectively treated with either ganciclovir or foscarnet and without CMV antigenemia at the start of valacyclovir) in the remaining 19 patients. The two treatment groups were well matched for the donor-recipient CMV serological status and other pre-transplant characteristics. CMV reactivation was detected by blood antigenemia testing using a commercially available immunofluorescence assay for CMV lower matrix protein pp65 in circulating leukocytes. For primary prophylaxis, 3/12 patients who received valacyclovir reactivated CMV compared to 24/31 patients in the control group (P < 0.001). For secondary prophylaxis, 5/19 valacyclovir patients reactivated compared to 16/24 control patients (P < 0.05). Valacyclovir was well tolerated except for infrequent and mild gastrointestinal side-effects. There was no difference in the incidence of CMV disease in the two groups. Prophylaxis with valacyclovir appears to be safe and efficacious in preventing both primary and secondary CMV reactivation in at-risk patients after allogeneic SCT. Larger prospective randomized studies will be required to confirm these observations.

Fatal upper and lower gastrointestinal cytomegalovirus disease following autologous peripheral blood stem cell transplantation

Although the life-threatening cytomegalovirus (CMV) disease is a well known complication following allogeneic hematopoietic stem cell transplantation (HSCT), it has been considered infrequent after autologous peripheral blood stem cell transplantation (PBSCT). On the other hand, the massive involvement of the gastrointestinal (GI) tract as the primary site of fatal CMV disease is particularly rare after autologous PBSCT. We present the case of a woman who suffered from CMV disease after high-dose busulphan/melphalan/thiotepa (BuMelTT) and autologous PBSCT. The primary site of infection was the GI tract, which was extensively affected. During the fifth week post-transplant the patient started with epigastralgia, diarrhea, fever, GI bleeding, and thrombocytopenia, and she died on day +52. Another case of fatal CMV disease among the few patients treated with BuMelTT has been recently reported, which suggests that the immunodeficiency associated with that regimen can be as intense as that occurring after allogeneic BMT.

Cytomegalovirus Infection and Abdominal Pain with Mycophenolate Mofetil

Mycophenolate mofetil (MMF) is an immunosuppressive agent that exerts relatively selective antiproliferative effects on T and B lymphocytes. Efficacy has been demonstrated in large-scale randomised studies, but the use of MMF is complicated by gastrointestinal upset and is associated with an increased incidence of tissue-invasive cytomegalovirus (CMV) disease. The gastrointestinal tract is a well recognised site for invasive CMV disease, and it has therefore been hypothesised that the abdominal pain commonly seen with MMF is related to CMV infection. This has only been tested in a single small uncontrolled study, where abdominal pain was associated with the presence of CMV on endoscopic biopsy. In contrast, the toxicity profile in 85 patients with psoriasis who had received relatively high dosages of mycophenolic acid, the active moiety of MMF, for up to 13 years showed that the incidence of gastrointestinal upset fell dramatically over time. We can find little evidence that CMV disease explains the gastrointestinal adverse event profile associated with MMF, and instead support the contention that high local concentrations of MMF have a direct toxic effect on cells of the small intestine. We do not recommend any changes to current policy on CMV prophylaxis in patients receiving MMF, although we recognise that some severe gastrointestinal adverse effects may be CMV-associated. The use of trough plasma concentration monitoring, divided doses and a gradually increasing dosage schedule may be of value in limiting toxicity.

Cytomegalovirus colitis during mycophenolate mofetil therapy for Wegener's granulomatosis

Cytomegalovirus (CMV) infection of the gastrointestinal tract is an increasingly recognized cause of morbidity and mortality during the course of HIV infection and in association with immunosuppressive pharmacotherapy. Mycophenolate mofetil, a novel immunosuppressive drug, is currently used in renal transplant recipients and is under evaluation for a variety of disorders. There is preliminary evidence to suggest that CMV reactivation may be more common during treatment with mycophenolate than with other immunosuppressive drugs. We present the case of a 59-year-old male with Wegener's granulomatosis who received mycophenolate and presented with guaiac-positive diarrhea 8 weeks after recovery from Salmonella brandenburg infection. CMV serology and assays for CMV antigens were entirely negative. Colonoscopy demonstrated pancolitis and examination of the specimens disclosed CMV infection. Ganciclovir was administered and the patient made an uneventful recovery. We discuss aspects of gastrointestinal CMV infection with an emphasis on pitfalls in diagnosis and the association with mycophenolate mofetil treatment. We also speculate as to the potential role of previous Salmonella infection and proinflammatory cytokines in CMV reactivation. In summary, when using mycophenolate, clinicians should be more aware of CMV reactivation and disease.

The influence of mycophenolate mofetil on the incidence and severity of primary cytomegalovirus infections and disease after renal transplantation

BACKGROUND

Mycophenolate mofetil (MMF) is increasingly used for immunosuppression after renal transplantation (RTx). The aim of our study was to investigate if the use of MMF has resulted in an increase in the frequency and severity of primary cytomegalovirus (CMV) infections.

METHODS

Retrospective study of adult RTx patients who were CMV seronegative and who received a kidney of a CMV seropositive donor in the period 1992-1997 (n=84). Twenty-four of these patients were treated with MMF (in combination with cyclosporin and prednisone; MMF+) and the other 60 were the control group (cyclosporin and prednisone; MMF-). No CMV prophylaxis was given. CMV infection was defined as CMV seroconversion of IgG antibodies. CMV disease was defined as CMV infection and fever in combination with one or more of the following: leukocytopenia, thrombocytopenia, elevated alanine aminotransferase, or histological evidence of tissue invasive disease.

RESULTS

The incidence of primary CMV infections was similar in both groups (MMF+, 75%; MMF-, 63%). CMV disease was more frequent in the MMF+ group than in the MMF- group (67 vs 30%, P<0.05). In the patients with CMV disease, the use of MMF did not affect severity of symptoms, frequency of tissue invasive disease, or frequency or duration of treatment with ganciclovir.

CONCLUSIONS

Addition of MMF to the immunosuppressive therapy after RTx did not result in an increase of primary CMV infections.However, these CMV infections led more often to CMV disease in patients treated with MMF than in those without MMF.

[Myasthenia gravis. Opportunistic cytomegalovirus infection after long-term azathioprine therapy]

Opportunistic infections after long-term treatment with azathioprine (AZA) have not been noted in patients with myasthenia gravis (MG). We report on a 56-year-old woman with generalized MG who presented with cytomegalovirus infection after being treated with AZA for 17 years. The indication for immunosuppressive treatment in MG should be regularly reconfirmed, particularly since at least 50% of patients can discontinue AZA after two to four years without risk of exacerbation.

Cytomegalovirus infection as a complication of OKT3 therapy in kidney transplant recipients

We compared the incidence of clinical CMV illness in 25 renal transplant recipients treated with OKT3 for steroid resistant cellular rejection with 88 renal transplant patients treated only with conventional immunosuppression (cyclosporin A and steroids). Nine (36%) patients in the OKT3 group developed CMV illness compared to (2.3%) amongst those treated conventionally (p < 0.0005). Patients who received OKT3 were divided into four groups according to the CMV antibody status of the donor and recipient. Six of the 9 episodes of CMV infection occurred in patients not previously exposed to CMV, who received a kidney from a CMV positive donor. Three (12%) of the patients treated with OKT3 died of CMV disease. A further 2 patients died of other causes giving an overall mortality in the OKT3 treated group of 20%. We concluded that when OKT3 therapy is used in association with donor/recipient CMV mismatch it is associated with a high CMV morbidity and mortality.

Immunotoxic effects of hexachlorobenzene on the pathogenesis of systemic, pneumonic and hepatic virus infections in the mouse

A quantitative histopathological method has been developed for the evaluation of the effects of hexachlorobenzene (HCB) on the pathogenesis of three virus infections in the mouse. Hexachlorobenzene was selected because a substantial amount of immunotoxicological data already exists with which we could compare our results. To establish the validity of the method a systemic virus infection (mouse cytomegalovirus, MCMV), a pneumonia causing virus (pneumonia virus of mice, PVM) and a hepatitis virus (mouse hepatitis virus, MHV) were used. We have compared the existing data with the actual pathological effects of hexachlorobenzene on virus disease processes, to gain a more realistic idea of the value of the risk assessment to be derived from extrapolating the in-vitro data in particular, to the in-vivo situation. The results show that the data derived from previous studies on the immunotoxicity of HCB were accurate in predicting the exacerbation of the viral hepatitis, especially in immunodeficient athymic 'nude' mice. It is proposed that this histopathological technique could be a useful technique in the evaluation of host resistance changes following exposure to potentially immunotoxic compounds, but caution will have to be exercised in interpretation in relation to human disease.

Therapy of a fatal murine cytomegalovirus infection with thymic humoral factor (THF-gamma 2) treated immune spleen cells

Infection of mice with murine cytomegalovirus (CMV) presents a model for the study of the role of the immune system in the pathogenesis of human CMV. We performed adoptive transfer experiments to evaluate the prospects for enhancing the anti-viral potential of murine CMV immune spleen cells by THF-gamma 2. Adult BALB/c mice resistant to murine CMV become highly susceptible following immunosuppression by cyclophosphamide. Recipient mice were injected with murine CMV and cyclophosphamide concomitantly, and 24 h later adoptive transfers of syngeneic immune spleen cells were performed. We showed that passive transfers of murine CMV immune spleen cells prevented the development of a fatal disease in 38% of the recipient mice. Daily injections of murine CMV immune donor mice with THF-gamma 2 enhanced considerably (93%) the therapeutic potential of virus-specific immune cells. These experiments provide direct evidence for the antiviral capacity of THF-gamma 2 through its immunomodulatory effect on immune T cells.

Altered susceptibility to viral respiratory infection during short-term exposure to nitrogen dioxide

The studies reported here focus on the relation of nitrogen dioxide exposure to susceptibility to viral respiratory infection in a murine model of pneumonia, created by intratracheal inoculation of an endogenous murine pathogen, mouse cytomegalovirus. The purpose of this work is to clarify the potential role of nitrogen dioxide exposure in the pathogenesis of viral infection of the lower respiratory tract. Previous human epidemiologic studies have presented conflicting information about the relationship of nitrogen dioxide to acute, self-limited episodes of respiratory illness, which are characteristic of viral respiratory infection. Some studies have found an association between exposure to elevated ambient levels of nitrogen dioxide and increased occurrence of acute respiratory illness. In one study this association was found to be strongest in children in the first two years of life. However, other epidemiologic studies have failed to observe this relation. To determine if there is scientific evidence for the possible relation of nitrogen dioxide exposure to human respiratory infection, our studies were performed to assess the impact of nitrogen dioxide on respiratory tract susceptibility to initial, or primary, infection, as well as to recurrent infection, or reinfection, with the identical virus. The latter mechanism of viral respiratory infection is of particular interest, since reinfection is a common method for the development of infection of the lower respiratory tract during early childhood. Outbred CD-1 mice were exposed to either air or nitrogen dioxide for six hours a day on two consecutive days prior to inoculation with murine cytomegalovirus, and then were reexposed to the same level of nitrogen dioxide for six hours a day on four consecutive days, beginning the day after viral inoculation. Susceptibility to primary infection was determined by inoculating animals with an amount of virus (10(2) plaque-forming units) that is too small to produce viral infection in the lungs of normal animals. Mice exposed to 5 parts per million (ppm) nitrogen dioxide routinely developed viral replication in the lung and histologic evidence of pneumonitis after inoculation with this amount of virus, whereas air-exposed animals did not. Most importantly, animals exposed to 5 ppm nitrogen dioxide could be infected with a viral inoculum that was 100-fold smaller than that required to consistently produce viral infection in air-exposed mice. Enhanced susceptibility to infection was found after exposure to 5 ppm nitrogen dioxide, but was not observed with exposure to 2.5 or 1 ppm nitrogen dioxide.(ABSTRACT TRUNCATED AT 400 WORDS)