Prevention of cytomegalovirus infection in organ transplant recipients

New Insights into Human Cytomegalovirus pUL52 Structure

Human cytomegalovirus (HCMV) can cause serious diseases in immunocompromised patients. Current antiviral inhibitors all target the viral DNA polymerase. They have adverse effects, and prolonged treatment can select for drug resistance mutations. Thus, new drugs targeting other stages of replication are an urgent need. The terminase complex (pUL56-pUL89-pUL51) is highly specific, has no counterpart in the human organism, and thus represents a target of choice for new antivirals development. This complex is required for DNA processing and packaging. pUL52 was shown to be essential for the cleavage of concatemeric HCMV DNA and crucial for viral replication, but its functional domains are not yet identified. Polymorphism analysis was performed by sequencing UL52 from 61 HCMV naive strains and from 14 HCMV strains from patients treated with letermovir. Using sequence alignment and homology modeling, we identified conserved regions and potential functional motifs within the pUL52 sequence. Recombinant viruses were generated with specific serine or alanine substitutions in these putative patterns. Within conserved regions, we identified residues essential for viral replication probably involved in CXXC-like or zinc finger motifs. These results suggest that they are essential for pUL52 structure/function. Thus, these patterns represent potential targets for the development of new antivirals.

Cytomegalovirus in Indian systemic lupus erythematosus patients: troublemaker or onlooker?

Introduction

cytomegalovirus (CMV) infection has been reported to be associated with onset/exacerbation of systemic lupus erythematosus (SLE). In an attempt to verify this, we studied CMV infection in SLE patients.

Methods

forty-two SLE patients were studied at 3-time points; disease onset/flare, at peak of immunosuppression (at 6 weeks) and at low doses of immunosuppression (at 6 months). We studied healthy blood donors as controls, only once. Clinical assessment and SLE Disease Activity Index scoring were done at each visit. RT-PCR and ELISA were performed to detect CMV viral-load and anti-CMV antibodies (Ab) respectively.

Results

nine of 106 patients had detectable viral-load (145-50,000 copies/ml). Of these nine, three patients had significant viral-load, 6 patients had low viral-loads of doubtful clinical significance. None of the patients developed CMV disease. Six of 42 cases were positive for IgM Abs. All controls were negative for CMV DNA as well as CMV IgM Abs. All samples from patients and controls were positive for CMV IgG Ab indicating widespread prevalence.

Conclusion

significantly, a higher seroprevalence of CMV IgM Abs against CMV observed in SLE patients when compared to controls, indicating possible reactivation due to immune modulation.

[The terminase complex, a relevant target for the treatment of HCMV infection]

Human cytomegalovirus (HCMV) is an important ubiquitous opportunistic pathogen that belongs to the betaherpesviridae. Primary HCMV infection is generally asymptomatic in immunocompetent individuals. In contrast, HCMV infection causes serious disease in immunocompromised patients and is the leading cause of congenital viral infection. Although they are effective, the use of conventional molecules is limited by the emergence of resistance and by their toxicity. New antivirals targeting other replication steps and inducing fewer adverse effects are therefore needed. During HCMV replication, DNA packaging is performed by the terminase complex, which cleaves DNA to package the virus genome into the capsid. With no counterpart in mammalian cells, these terminase proteins are ideal targets for highly specific antivirals. A new terminase inhibitor, letermovir, recently proved effective against HCMV in phase III clinical trials. However, its mechanism of action is unclear and it has no significant activity against other herpesvirus or non-human CMV.

Impact of targeted oral ganciclovir prophylaxis for transplant recipients of livers from cytomegalovirus-seropositive donors

OBJECTIVES

Symptomatic cytomegalovirus (CMV) infection can cause significant morbidity and occasional mortality after liver transplantation. In a previous audit, we showed that donor CMV seropositivity (D+) was a risk factor for symptomatic infection, and we estimated the likely clinical and financial impact of 14 weeks of oral ganciclovir prophylaxis given to recipients of CMV-seropositive organs. In August 2001, we adopted this policy of targeted oral ganciclovir prophylaxis for recipients of CMV-seropositive livers.

METHOD

The additional costs of adopting targeted prophylaxis policy for 1 year, patient and doctor compliance with the new strategy, and its clinical impact were analysed.

RESULTS

Targeted prophylaxis reduced the incidence of symptomatic CMV infection from 9.5% (in the earlier cohort that did not receive prophylaxis) to 5.8% (P = NS). Symptomatic infection was not observed in CMV-seropositive recipients of CMV-seropositive donor livers (P = 0.06 for comparison of the 2 cohorts), but the incidence of symptomatic infection in the CMV-seronegative recipients of CMV-seropositive organs did not change. However, symptomatic infection appeared to be less severe and was delayed by ganciclovir prophylaxis (median time from transplantation to symptom onset 96 vs. 39 days without prophylaxis). Death attributable to CMV infection was not observed in the cohort that received prophylaxis. The additional cost associated with implementation of the prophylaxis strategy was 108,068 pounds sterlings.

CONCLUSION

Targeted CMV prophylaxis with oral ganciclovir reduces the incidence and severity of symptomatic infection and appears to be a cost-effective means of improving outcome following liver transplantation.

Monitoring for human cytomegalovirus infection in solid organ transplant recipients through antigenemia and glycoprotein N (gN) variants: evidence of correlation and potential prognostic value of gN genotypes

Human cytomegalovirus (HCMV) ORF UL73 encodes the envelope glycoprotein gpUL73-gN, which shows seven genotypes (gN-1, gN-2, gN-3a, gN-3b, gN-4a, gN-4b, gN-4c). The goal of this study was to determine retrospectively the distribution of gN variants in solid organ transplant recipients with HCMV infection and to establish an association with parameters important for monitoring post-transplantation clinical course during a follow-up of up to 2 years. Peripheral blood leukocytes from 40 solid organ transplant recipients were analysed for pp65-antigen by immunofluorescence and gN genotyped by sequencing or RFLP analysis. A correlation between gN genotypes and antigenemia peak was found, showing a highly significant difference between gN-1 and gN-4b variants (P<0.005). In particular, gN-1 seems to be associated with patients developing low level antigenemia (<50 pp65-positive cells/2 x 10(5) PBLs; PPV = 90%), whereas gN-4b predicts significantly higher values (>50 pp65-positive cells/2 x 10(5) PBLs; PPV = 80%). Furthermore, the onset of positive antigenemia is significantly earlier in patients infected with a gN-4b strain, compared with those infected by a gN-1 variant. Reported data further support a role for gN genotypes in HCMV pathogenesis. gN-1 and gN-4b show a significantly different virulence and could serve as early predictors for the progression of HCMV infection in transplant patients.

Prevention, detection, and management of early bacterial and fungal infections in a preclinical cardiac xenotransplantation model that achieves prolonged survival

BACKGROUND

We analyzed bacterial and fungal infectious complications in a cohort of 16 consecutive experiments with the longest surviving cardiac xenografts to date.

METHODS

Transgenic, porcine-to-baboon, heterotopic (abdomen) cardiac xenotransplantation was performed in 16 consecutive experiments, using rapamycin, tacrolimus, corticosteroids, anti-CD20 monoclonal antibody, and an alpha-Gal-PEG polymer, as immunosuppression. Prophylactic anti-microbials included i.v. trimethoprim/sulfamethoxazole, oral ganciclovir/valganciclovir, and oral itraconazole. An episode of bacterial infection was defined as a positive blood and/or wound culture with: leukocytosis, fever >101.5 degrees F, and/or clinical deterioration.

RESULTS

Mean graft survival was 71 +/- 29 days; the longest was 113 days. There were 23 episodes of bacterial infection; 14 resolved with treatment. The mean time to the first episode of infection was 44 +/- 21 days (n=12). Eight of 16 deaths were due to infection: two bacterial-only, two cytomegalovirus (CMV) only, four both bacterial and CMV, and none fungal. The frequency of infection was 1, 2.8, and 1.8 episodes/100 survival days, respectively, for animals whose grafts survived for 30 to 59, 60 to 89, and >90 days. CMV infection (reviewed in detail in a separate communications) was due to baboon CMV, and was associated with low serum levels of ganciclovir.

CONCLUSION

In a cardiac xenograft model that achieved prolonged (>3 months) survival, bacteremia was common, but usually reversible, and fungal infection was prevented with prophylaxis. The level of immunosuppression required to achieve clinically meaningful xenograft survival is associated with a level of bacterial and fungal infectious complications that is manageable and similar to the early clinical experiences in human transplantation. Further research will determine if the viral infectious complications observed in these experiments can be reduced by optimizing blood levels of anti-viral prophylaxis and monitoring viral polymerase chain reaction levels.

Können CMV-Infekte nach Herztransplantation durch dreimonatige antivirale Prophylaxe reduziert werden? 7 Jahre Erfahrung mit Ganciclovir

BACKGROUND

In the early phase after heart transplantation (HTX) patients are at high risk for infection because of intensified immunosuppression. This retrospective study evaluates the efficacy of a three-month antiviral cytomegalovirus (CMV) prophylaxis.

PATIENTS AND METHODS

133 patients received a three-month combined intravenous and oral CMV prophylaxis with Ganciclovir (Cymevene after HTX between 1997 and April 2003 (group II). They were compared to a historical group consisting of 40 patients, who had undergone HTX between 1995 and 1996 (group I; CMV-prophylaxis: hyperimmune globuline (Cytotect) for the first post-operative month in combination with orally administered aciclovir (Zovirax) for 6 months). Demographic data of organ recipients and donors in both groups were comparable, except for underlying cardiac diseases (p = 0.016). All patients had identical postoperative immunosuppressive regimes.

RESULTS

Group II had a significantly lower mortality rate (GI: 37.5%, GII: 9.8%; p < 0.001); one year survival (p = 0.001) and overall survival (p = 0.001) were significantly better than in group I. Patients of group II had fewer rejection episodes > or = grade II ISHLT requiring treatment (p < 0.001). Group II presented significantly fewer positive CMV blood samples (p = 0.005) and CMV infections (26% versus 47,5% in GI; p = 0.008), and a later onset of infections after HTX than group I (group I with a mean interval of 5.8 weeks after HTX, group II: 24.8 weeks after HTX; p < 0.001).

CONCLUSION

Incidence of CMV infection was significantly lowered under ganciclovir prophylaxis, infections occurred at a later time point after HTX, when patients were immunologically more competent. The proportion of higher grade rejection episodes was markedly reduced and survival was improved.

Comparison of intravenous ganciclovir and cytomegalovirus hyperimmune globulin pre-emptive treatment in cytomegalovirus-positive heart transplant recipients

BACKGROUND

We compared the use of intravenous ganciclovir and cytomegalovirus hyperimmune globulin (CMVIG) as a pre-emptive treatment for cytomegalovirus (CMV)-positive heart transplant recipients.

METHODS

Of 59 CMV-seropositive adult heart transplant recipients enrolled in Group 1, 37 tested positive for pp65 antigen within 12 weeks post-transplantation. These patients were randomized to receive either intravenous ganciclovir (n = 23) or CMVIG (n = 14). Group 2 included 133 CMV-seropositive heart transplant recipients who were not tested for CMV antigenemia and who received no anti-CMV therapy.

RESULTS

CMV disease developed in 0 of 59 patients from Group 1, and in 27 of 133 patients (20%) in Group 2 (p = 0.0001). The incidence of superinfections was lower in Group 1 (0.28 +/- 0.46) than in Group 2 (1.10 +/- 1.33) (p = 0.01). The 2 groups did not differ with regard to incidence of rejection (0.7 +/- 0.9 in Group 1 vs 1.0 +/- 1.2 in Group 2; p = NS), transplant coronary artery disease at 1 year (14% in Group 1 vs 16% in Group 2; p = NS) or post-transplant lymphoproliferative disease (0% in Group 1 vs 2% in Group 2; p = NS). Ganciclovir and CMVIG therapies were associated with similar rates of rejection (0.52 +/- 0.6 with ganciclovir vs 0.50 +/- 0.60 with CMVIG; p = NS), superinfection (0.30 +/- 0.48 with ganciclovir vs 0.25 +/- 0.46 with CMVIG; p = NS), and transplant coronary artery disease at 1 year (13% with ganciclovir vs 14% with CMVIG, p = NS).

CONCLUSIONS

The pre-emptive anti-CMV approach is superior to prophylaxis in CMV-seropositive heart transplant recipients. Both ganciclovir and CMVIG are equally effective.