Cytomegalovirus-specific CD4 and CD8 T cell responses in infants and children.

Congenital cytomegalovirus (CMV) infection is the most common congenital infection causing childhood morbidity. The pathogenetic mechanisms behind long-term sequelae are unclear, but long-standing viremia as a consequence of the inability to convert the virus to a latent state has been suggested to be involved. Whereas primary CMV infection in adults is typically rapidly controlled by the immune system, children have been shown to excrete virus for years. Here, we compare T cell responses in children with congenital CMV infection, children with postnatal CMV infection and adults with symptomatic primary CMV infection. The study groups included 24 children with congenital CMV infection, 19 children with postnatal CMV infection and eight adults with primary CMV infection. Among the infants with congenital CMV infection, 13 were symptomatic. T cell responses were determined by analysis of interferon gamma production after stimulation with CMV antigen. Our results show that whereas adults display high CMV-specific CD4 T cell responses in the initial phase of the infection, children younger than 2 years have low or undetectable responses that appear to increase with time. There were no differences between groups with regard to CD8 T cell function. In conclusion, inadequate CD 4 T cell function seems to be involved in the failure to get immune control of the CMV infection in children younger than 2 years of age with congenital as well as postnatal CMV infection.

Poor outcome of adenovirus infections in adult hematopoietic stem cell transplant patients with sustained adenovirus viremia.

The outcome of adenovirus (ADV) infections in adult hematopoietic stem cell transplant (HSCT) patients remains poorly characterized. We studied 14 adults and 3 children, who had undergone HSCT and had developed ADV viremia. Peak ADV DNA levels were significantly higher in patients with ADV diseases than in those without (P=0.03). All children survived the ADV infections. Among the 14 adult HSCT patients, 11 were treated with cidofovir, 2 with ribavirin, and 1 did not receive antiviral treatment. Six of the 13 (46%) treated patients developed ADV diseases and 3 of them (23%) died of ADV infections. Sustained viremia (≥3 positive polymerase chain reaction assays during follow-up) was detected in all patients who finally died of ADV infections. However, 2 adults having had transient ADV viremia either survived or died of diseases other than ADV infections. Our study indicates that the outcome of adult HSCT patients with sustained ADV viremia may be poor, even for those who have received anti-ADV treatment.

Congenital cytomegalovirus infection: the impact of cerebral cortical malformations.

AIM: Cytomegalovirus has been suggested to have a teratogenous influence during the migration of neural cells from the ventricular zones to the cortex during the gestational period. The aim of this study was to investigate the prevalence of congenital cytomegalovirus infections in a cohort of children with neurological disability and cerebral cortical malformations recognized by neuroimaging. METHODS: Twenty-six children with neurological disability and cerebral cortical malformations were investigated retrospectively for congenital cytomegalovirus infection by analysing the dried blood spot samples for cytomegalovirus deoxynucleic acid using qualitative polymerase chain reaction. RESULTS: CMV DNA in the dried blood spot samples was found in four out of 26 children. Two of these four had severe disabilities with mental retardation, autism, spastic cerebral palsy, epilepsy and deafness. A third child had epilepsy and unilateral cerebral palsy, while the fourth had a mild motor coordination dysfunction and hearing deficit. CONCLUSION: In our study, the number of congenital cytomegalovirus infections in children with cerebral cortical malformations was higher (4/26) than expected with reference to the birth prevalence (0.2-0.5%) of congenital cytomegalovirus infection in Sweden. We thus conclude that congenital cytomegalovirus infection should be considered in children with cortical malformations of unknown origin.

Quantification of adenovirus DNA in unrelated donor hematopoietic stem cell transplant recipients.

BACKGROUND: Adenovirus (AdV) infection is a life threatening condition in immunosuppressed patients. Quantitative AdV assays can improve the clinical management of these patients. OBJECTIVES: To evaluate quantitative measurement of AdV DNA with PCR in blood from hematopoietic stem cell transplant (HSCT) recipients. STUDY DESIGN: Quantitative PCR was used to measure viral DNA levels of AdV in consecutive blood samples from 40 HSCT recipients (27 adults and 13 children) during a 1-year post-engraftment period. All patients received grafts from unrelated donors and were given anti-T-cell antibodies in the conditioning regimen. RESULTS: In the group of 40 patients, six (15%) had detectable AdV DNA in blood for different lengths of time. None of these six patients suffered from severe graft-versus-host disease. In three of the patients a high AdV viral load (>10,000 copies/mL) was detected, one of whom also had high viral load of EBV and CMV and one of EBV only. These three patients died within 2 months after detection of ADV viremia. A low AdV viral load (<500 copies/mL) was detected in three surviving patients and they did not have concomitant high viral load of neither CMV nor EBV. CONCLUSIONS: AdV viremia was present in 15% of the HSCT recipients and a high AdV viral load was associated with fatal outcome. Screening for AdV DNA with quantitative PCR in blood may be of clinical importance in allogeneic HSCT recipients in order to prevent severe clinical virological complications.

Real-time monitoring of cytomegalovirus infections after stem cell transplantation using the TaqMan polymerase chain reaction assays.

BACKGROUND: Real-time monitoring of cytomegalovirus (CMV) infections in transplant patients demands a rapid and high-throughput CMV DNA quantification method. METHODS: TaqMan polymerase chain reaction assays based on CMV immediate early protein exon 4 and glycoprotein B were developed and were compared with a COBAS AMPLICOR CMV MONITOR (CMM) test for quantifying CMV DNA in peripheral blood leukocytes from seven stem cell transplant patients having received antiviral treatment. RESULTS: There was a good correlation between the TaqMan assays and the CMM test for CMV DNA quantification. The throughput of the TaqMan assays was, however, about 3 times higher than that of the CMM test. The CMV DNA dynamics patterns determined by the TaqMan polymerase chain reaction were well in line with the outcome of the antiviral therapy. CONCLUSIONS: The TaqMan assays may potentially serve as a useful tool for rapid quantification of CMV infections in stem cell transplant patients.

Results of different strategies for reducing cytomegalovirus-associated mortality in allogeneic stem cell transplant recipients.

BACKGROUND: Several preventive strategies against cytomegalovirus (CMV) disease have been developed during the last decade. These have frequently been used in combination, and it has been difficult to identify each strategy's contribution. METHODS: Risk factors for CMV disease, death in CMV disease and transplant-related mortality were analyzed in 584 patients, who underwent a total of 594 allogeneic bone marrow transplants. RESULTS: The overall probability of CMV disease was 8.9%. No seronegative patient who had a seronegative marrow donor developed CMV disease. The corresponding probabilities for seronegative patients with seropositive donors, seropositive patients with seronegative donors, and seropositive patients with seropositive donors were 5.4%, 13.7%, and 11.7%, respectively. In multivariate Cox models, the use of preemptive antiviral therapy and being CMV-seronegative reduced the risk for CMV disease, CMV-associated death, and transplant-related mortality (TRM). Patients who received unrelated or mismatched family donor transplants had increased risks for CMV disease, CMV-associated death, and TRM. Older age was a significant risk factor for CMV disease and TRM. A total of 258 patients who were monitored by polymerase chain reaction for CMV DNA were analyzed separately to assess whether addition of another CMV preventive strategy could give benefit. Patients who received mismatched or unrelated donor transplants had increased risk for CMV disease, death in CMV disease, and TRM. High-dose acyclovir prophylaxis or addition of intravenous immune globulin had no influence. CONCLUSIONS: Preemptive therapy based on polymerase chain reaction for CMV DNA was associated with reduced risks for CMV disease, CMV-associated death, and TRM, whereas other prophylactic modalities did not give additional benefit.

Loss of seroreactivity against human papillomavirus (HPV) in bone marrow transplant recipients.

Sera from 19 autologous and 35 allogeneic bone marrow transplant (BMT) patients at Huddinge University Hospital were analyzed by different ELISA assays before and 1 year after BMT for the presence of IgG antibodies towards human papillomavirus (HPV). One assay was a peptide-based enzyme-linked immunoadsorbent assay (ELISA). These peptides were derived from the amino acid sequences of the two major viral capsid proteins of HPV 16, p(31) L1 and (p49) L2. The other was an ELISA using HPV-type 16 virus-like particles (VLPs) as antigens. Before BMT 13/19 autologous and 14/35 allogeneic BMT patients were IgG positive towards p49 (L2). Reactivity to p31 (L1) was less frequent and was only observed in 7/19 autologous and 3/35 allogeneic BMT patients. One year after BMT 1/4 of the autologous and 2/3 of the allogeneic BMT patients who were IgG positive to p49 (L2) lost these antibodies as measured by the peptide ELISA assay. Regarding IgG reactivity to p31 (L1), one of the seven p31 (L1) positive autologous BMT patients and all three of the p31 (L1) positive allogeneic BMT patients lost this reactivity 1 year after BMT. Of all the 19 autologous and the 35 allogeneic BMT patients only two allogeneic BMT patients were weakly IgG reactive towards VLPs and 1 year after BMT this activity was lost in one of the two patients.

Long-term immunity to poliovirus after vaccination of allogeneic stem cell transplant recipients.

Revaccination with poliovirus after allogeneic stem cell transplant (SCT) is usually effective, but the longevity of this immunity is unknown. Therefore, poliovirus immunity was studied in 134 patients having survived at least 5 years after vaccination. The median follow-up from vaccination was 8 years (1-19 years). In all, 21 (15.6%) patients had become seronegative to at least one of the poliovirus serotypes during follow-up. The estimated probabilities of remaining immune to poliovirus at 5 and 10 years after vaccination were 94 and 94% for subtype 1, 98 and 94% for subtype 2, and 93 and 90% for subtype 3, respectively. In multivariate analysis, the only risk factor for loss of immunity was younger patient age (P < 0.01), and there was a strong trend for patients with chronic GVHD to lose immunity more rapidly (P = 0.07). A total of 14 patients received a booster dose of an inactivated poliovirus vaccine and all responded. We conclude that poliovirus immunity is retained long term after revaccination in most patients after allogeneic SCT.

Measles immunity after allogeneic stem cell transplantation; influence of donor type, graft type, intensity of conditioning, and graft-versus host disease.

During follow-up after allogeneic stem cell transplantation (SCT), patients frequently lose their immunity to infectious agents such as measles. The aim of this study was to analyze the influence of different factors on measles immunity. In total, 395 patients with a disease-free survival of at least 1 year were included. Measles vaccination was given at 2 years after SCT to children and young adults without chronic GVHD or ongoing immunosuppression. In all, 264 patients had matched sibling donors and 131 either mismatched family or unrelated donors. Totally, 318 patients received bone marrow and 77 peripheral blood stem cells. Overall, 375 patients had undergone myeloablative and 20 nonmyeloablative conditioning. Out of 395 patients, 133 (34%) were seronegative to measles. In multivariate models, younger age or being vaccinated to measles, rather than previous measles disease, before transplantation were risk factors both for becoming seronegative and to have doubtfully protective immunity to measles. Acute GVHD grade II-IV was a risk factor for seronegativity and blood stem cells a risk factor for doubtfully protective immunity. Children and young adults previously immunized to measles have a high risk for becoming vulnerable to a measles infection. Since measles is again circulating in many countries and measles is a serious infection after SCT, vaccination should be considered.

Use of a semi-quantitative PCR for cytomegalovirus DNA as a basis for pre-emptive antiviral therapy in allogeneic bone marrow transplant patients.

The aim of this study was to evaluate the efficacy of pre-emptive antiviral therapy, based on a semi-quantitative nested PCR for cytomegalovirus (CMV) DNA in leukocytes, for the prevention of CMV disease after allogeneic BMT. Fifty-eight patients were prospectively followed with PCR for CMV DNA and antiviral therapy with ganciclovir was initiated after two consecutive positive tests. The levels of CMV DNA were determined by serial dilutions of the positive samples. The probability of detection of CMV DNA was 48.3% and the probability of CMV disease 6% at 100 days after BMT. Patients with CMV disease had higher CMV DNA levels compared with patients without CMV disease (P = 0.001). In comparison to 58 matched historical controls detection of CMV DNA was 5 days earlier (NS) and antiviral therapy could be initiated 10 days earlier in patients followed by PCR (P = 0.05). Pre-emptive antiviral therapy was given to 28 patients in a total of 36 courses. Patients became negative in PCR after 28 of 36 courses (77%). We conclude that PCR for CMV DNA can be used for early detection of CMV infection and as the basis of initiation of pre-emptive antiviral therapy in BMT patients.