The challenge of respiratory virus infections in hematopoietic cell transplant recipients

Immunosuppressed patients with pandemic influenza A 2009 (H1N1) virus infection

The purpose of this paper was to prospectively characterize the clinical manifestations and outcomes of confirmed influenza A 2009 (H1N1) virus infection in immunosuppressed patients with hospital admission and compare them with those of a general population. A multicenter prospective cohort study was carried out. All adult patients admitted to 13 hospitals in Spain with confirmed influenza A 2009 (H1N1) virus infection from June 12, 2009 to November 11, 2009 were included. Risk factors for complicated influenza infection were studied in immunosuppressed patients. Overall, 559 patients were included, of which 56 were immunosuppressed, nine with solid or hematological malignancies, 18 with solid-organ transplant recipients, 13 with corticosteroid therapy, and six with other types of immunosuppression. Clinical findings at diagnosis were similar in both groups. Nineteen immunosuppressed patients had pneumonia (33.9%). Immunosuppressed patients with pandemic influenza had bacterial co-infection more frequently (17.9% vs. 6.4%, p = 0.02), specifically, gram-negative bacilli and Staphylococcus aureus infections. Mortality was higher in immunosuppressed patients (7.1% vs. 1.8%, p < 0.05). The only modifiable risk factor of complicated influenza A 2009 (H1N1) was delayed antiviral therapy. In immunosuppressed patients, influenza A 2009 (H1N1) virus infection has higher mortality than in non-immunosuppressed individuals. Bacterial co-infection is common in complicated cases.

Perspective: emerging challenges in the treatment of influenza and parainfluenza in transplant patients

Influenza, respiratory synctial virus, and parainfluenza are common respiratory infections in immunocompromised transplant recipients, causing significant morbidity and mortality in this patient population. This paper focuses on influenza and parainfluenza virus infections in transplant patients with emphasis on the pandemic 2009 H1N1 influenza infection. Current antiviral treatment recommendations for influenza and parainfluenza in immunocompromised patients as well as novel investigational therapeutic approaches currently being tested in the clinic are discussed. In addition to the morbidity and mortality caused by these viruses, the development of multidrug resistance leading to transmission of resistant viruses is of great public health concern. The development of effective new therapies for influenza and parainfluenza in these high-risk patients is needed with randomized placebo-controlled studies to assess their clinical utility.

Viral infections of the lower respiratory tract: old viruses, new viruses, and the role of diagnosis

Viral infections of the lower respiratory tract cause an enormous disease burden in children, and the role of respiratory viruses in serious lower respiratory tract infections (LRTIs) in older adults is increasingly appreciated. Although viruses are responsible for a large proportion LRTIs, antibiotics are often prescribed. New diagnostic platforms have the potential to detect a wider range of established and newly discovered viruses with greater sensitivity. This will create additional challenges. Although it is clear that influenza, parainfluenza, respiratory syncytial virus, human metapneumovirus, and adenovirus are important causes of pneumonia, the role of rhinoviruses and some of the newly described viruses, including human coronaviruses and bocavirus, is harder to determine. Better diagnostic tests that establish the cause of LRTIs in children have the potential to both reduce overall antibiotic use and to improve the targeted use of antibiotics. In addition, rapid identification of viral infections can help control nosocomial transmission.

Differences in clinical outcomes after 2009 influenza A/H1N1 and seasonal influenza among hematopoietic cell transplant recipients

It is not known whether pandemic 2009 influenza A/H1N1 (2009 H1N1) leads to more serious disease than seasonal influenza in hematopoietic cell transplant (HCT) recipients. In a retrospective study in HCT recipients with virologically proven influenza virus infection, a total of 161 HCT recipients (18 2009 H1N1, 103 seasonal influenza A, and 40 seasonal influenza B) were analyzed. In multivariable analyses, more patients with 2009 H1N1 had lower respiratory tract disease (LRD), hypoxemia, and prolonged viral shedding compared with seasonal influenza A. Seasonal influenza A and B outcomes were similar. There was no difference in overall and influenza-associated mortality among influenza virus types. Both early and delayed administration of antiviral therapy was shown to be beneficial in terms of decreased rates of development of LRD, although earlier intervention appeared to be more effective. Profound lymphopenia and lack of early antiviral therapy were associated significantly with LRD, hypoxemia, and death. High-dose corticosteroid treatment (≥ 1 mg/kg) given at the time of influenza diagnosis was associated with a reduced risk for mechanical ventilation. Thus, our data suggest that infection with 2009 influenza A/H1N1 resulted in more severe respiratory disease in HCT recipients compared with seasonal influenza.

[Role of viral infections in immunosuppressed patients]

Ser receptor de un trasplante de órgano sólido, así como recibir tratamiento quimioterápico para una enfermedad hematólógica maligna, predispone claramente a padecer infecciones virales tanto comunes como oportunistas, de origen tanto comunitario como procedentes del donante de órganos y/o de una reactivación de un virus latente endógeno. Herpes virus y más especialmente citomegalovirus y virus de Epstein-Barr son los que con más frecuencia afectan a estos enfermos, así como los virus respiratorios. El tratamiento consiste en la combinación de reducir la inmunodepresión inducida junto con tratamiento antiviral. Se ha realizado una revisión de la literatura pormenorizada y actualizada de la epidemiología, la patogenia, las manifestaciones clínicas y la aproximación terapéutica de las infecciones virales en estos enfermos.

Reducing the risk for transplantation-related mortality after allogeneic hematopoietic cell transplantation: how much progress has been made?

PURPOSE

Transplantation-related mortality (TRM) is a major barrier to the success of allogeneic hematopoietic cell transplantation (HCT).

PATIENTS AND METHODS

We assessed changes in the incidence of TRM and overall survival from 1985 through 2004 in 5,972 patients younger than age 50 years who received myeloablative conditioning and HCT for acute myeloid leukemia (AML) in first complete remission (CR1) or second complete remission (CR2).

RESULTS

Among HLA-matched sibling donor transplantation recipients, the relative risks (RRs) for TRM were 0.5 and 0.3 for 2000 to 2004 compared with those for 1985 to 1989 in patients in CR1 and CR2, respectively (P < .001). The RRs for all causes of mortality in the latter period were 0.73 (P = .001) and 0.60 (P = .005) for the CR1 and CR2 groups, respectively. Among unrelated donor transplantation recipients, the RRs for TRM were 0.73 (P = .095) and 0.58 (P < .001) for 2000 to 2004 compared with those in 1990 to 1994 in the CR1 and CR2 groups, respectively. Reductions in mortality were observed in the CR2 group (RR, 0.74; P = .03) but not in the CR1 group.

CONCLUSION

Our results suggest that innovations in transplantation care since the 1980s and 1990s have reduced the risk of TRM in patients undergoing allogeneic HCT for AML and that this reduction has been accompanied by improvements in overall survival.

Long-term shedding of influenza A virus in stool of immunocompromised child

In immunocompromised patients, influenza infection may progress to prolonged viral shedding from the respiratory tract despite antiviral therapy. We describe chronic influenza A virus infection in an immunocompromised child who had prolonged shedding of culturable influenza virus in stool.

Impact of corticosteroid treatment and antiviral therapy on clinical outcomes in hematopoietic cell transplant patients infected with influenza virus

The impact of cytokines induced during influenza infection has been described, but the effect of corticosteroids on clinical outcomes is unclear. Although antiviral therapy has been well studied in immunocompetent subjects, few data exist on its clinical efficacy in immunocompromised populations. Data from 143 hematopoietic cell transplant recipients with documented seasonal influenza infection were reviewed to examine the impact of different corticosteroid regimens and antiviral therapy on clinical outcomes. In multivariable analyses, there was no observed difference between patients who received no, low doses (<1 mg/kg/day), or high doses (≥ 1 mg/kg/day) of corticosteroids with regard to the development of lower respiratory tract disease (LRD), hypoxemia, need for mechanical ventilation, or death. However, treatment with high-dose steroids was associated with a trend toward prolonged viral shedding (odds ratio [OR], 3.3; 95% confidence interval [CI], 1.0-11; P = .05). In multivariable analyses, antiviral therapy initiated to treat upper respiratory tract infection (URI) was associated with fewer cases of LRD (OR, 0.04; 95% CI, 0-0.2; P < .01) and fewer hypoxemia episodes (OR, 0.3; 95% CI, 0.1-0.9; P = .03). Our results suggest that corticosteroids are not associated with adverse clinical outcomes in hematopoietic cell transplant recipients infected with influenza, although use of higher doses may delay viral clearance. Antiviral therapy initiated during the URI phase reduced the risk of LRD and hypoxemia.

Hematopoietic cell transplantation and emerging viral infections

Viral infections remain important causes of morbidity and mortality in hematopoietic cell transplant recipients. More recent developments in preparative regimens and graft manipulations, as well as the control of well-recognized post-transplant infections by the introduction of prophylaxis and preemptive strategies, have influenced the timing and the epidemiology of infections. As new pathogens, such as human metapneumovirus (HMPV), human bocavirus, human coronaviruses HCoV-NL63 and HCoV-HKU1, human herpesviruses HHV-6 and HHV-7, and polyomaviruses, have emerged, it is fundamental to determine the significance of the newly discovered viruses and their role in the transplantation field. This article summarizes recent data on epidemiology and laboratory diagnosis of new pathogens, as well as clinical features and management of the associated infectious complications. J. Med. Virol. 82:528-538, 2010. (c) 2010 Wiley-Liss, Inc.

How I treat influenza in patients with hematologic malignancies

The 2009 H1N1 influenza pandemic has heightened the interest of clinicians for options in the prevention and management of influenza virus infection in immunocompromised patients. Even before the emergence of the novel 2009 H1N1 strain, influenza disease was a serious complication in patients with hematologic malignancies receiving chemotherapy or undergoing hematopoietic cell transplantation. Here we review the clinical manifestations of seasonal and 2009 H1N1 influenza and discuss current diagnosis, antiviral treatment, and prophylaxis options. We also summarize infection control and vaccination strategies for patients, family members, and caregivers.

Residues in the heptad repeat a region of the fusion protein modulate the virulence of Sendai virus in mice

While the molecular basis of fusion (F) protein refolding during membrane fusion has been studied extensively in vitro, little is known about the biological significance of membrane fusion activity in parainfluenza virus replication and pathogenesis in vivo. Two recombinant Sendai viruses, F-L179V and F-K180Q, were generated that contain F protein mutations in the heptad repeat A region of the ectodomain, a region of the protein known to regulate F protein activation. In vitro, the F-L179V virus caused increased syncytium formation (cell-cell membrane fusion) yet had a rate of replication and levels of F protein expression and cleavage similar to wild-type virus. The F-K180Q virus had a reduced replication rate along with reduced levels of F protein expression, cleavage, and fusogenicity. In DBA/2 mice, the hyperfusogenic F-L179V virus induced greater morbidity and mortality than wild-type virus, while the attenuated F-K180Q virus was much less pathogenic. During the first week of infection, virus replication and inflammation in the lungs were similar for wild-type and F-L179V viruses. After approximately 1 week of infection, the clearance of F-L179V virus was delayed, and more extensive interstitial inflammation and necrosis were observed in the lungs, affecting entire lobes of the lungs and having significantly greater numbers of syncytial cell masses in alveolar spaces on day 10. On the other hand, the slower-growing F-K180Q virus caused much less extensive inflammation than wild-type virus, presumably due to its reduced replication rate, and did not cause observable syncytium formation in the lungs. Overall, the results show that residues in the heptad repeat A region of the F protein modulate the virulence of Sendai virus in mice by influencing both the spread and clearance of the virus and the extent and severity of inflammation. An understanding of how the F protein contributes to infection and inflammation in vivo may assist in the development of antiviral therapies against respiratory paramyxoviruses.

Lower respiratory tract respiratory virus infections increase the risk of invasive aspergillosis after a reduced-intensity allogeneic hematopoietic SCT

We have analyzed the incidence and risk factors for the occurrence of invasive aspergillosis (IA) among 219 consecutive recipients of an allogeneic hematopoietic SCT after a reduced-intensity conditioning regimen (Allo-RIC). Twenty-seven patients developed an IA at a median of 218 days (range 24–2051) post-Allo-RIC, for a 4-year incidence of 13% (95% confidence interval 4–24%). In multivariate analysis, risk factors for developing IA were steroid therapy for moderate-to-severe graft vs host disease (GVHD) (Hazard Ratio (HR) 2.9, P=0.03), occurrence of a lower respiratory tract infection (LRTI) by a respiratory virus (RV) (HR 4.3, P<0.01) and CMV disease (HR 2.8, P=0.03). Variables that decreased survival after Allo-RIC were advanced disease phase (HR 1.9, P=0.02), steroid therapy for moderate-to-severe GVHD (HR 2.2, P<0.01), not developing chronic GVHD (HR 4.3, P<0.01), occurrence of LRTI by an RV (HR 3.4, P<0.01) and CMV disease (HR 2, P=0.01), whereas occurrence of IA had no effect on survival (P=0.5). Our results show that IA is a common infectious complication after an Allo-RIC, which occurs late post-transplant and may not have a strong effect on survival. An important observation is the possible role of LRTI by conventional RVs as risk factors for IA.

Adoptive transfer of virus-specific and tumor-specific T cell immunity

The adoptive transfer of T cells isolated or engineered to have specificity for diseased cells represents an ideal approach for the targeted therapy of human viral and malignant diseases. The therapeutic potential of adoptive T cell therapy for infections and cancer was demonstrated in rodent models long ago, but the task of translating this approach into an effective clinical therapy has not been easy. Carefully designed clinical trials have evaluated the transfer of antigen-specific T cells in humans, and provided insight into the barriers to efficacy and strategies to improve T cell therapy. The importance of altering the host environment to facilitate persistence and function of transferred T cells and intrinsic properties of T cells that are selected or engineered for therapy in determining their fate in vivo are key issues that have recently emerged and are informing the design of the next generation of clinical trials.