Influenza viremia and the potential for blood-borne transmission

Passive immunotherapies for the next influenza pandemic

Influenzavirus is among the most relevant candidates for a next pandemic. We review here the phylogeny of former influenza pandemics, and discuss candidate lineages. After briefly reviewing the other existing antiviral options, we discuss in detail the evidences supporting the efficacy of passive immunotherapies against influenzavirus, with a focus on convalescent plasma.

Low rate of detection of SARS-CoV-2 RNA in deceased tissue donors

Given the possibility for disease transmission, this study was performed to determine whether there is detectable SARS-CoV-2 viral RNA in the blood of deceased tissue donors. A retrospective analysis of blood samples from eligible deceased tissue donors from Oct 2019 through June 2020 was performed. Plasma aliquots were initially tested with a SARS-CoV-2 NAT Assay; positive samples were further tested using an alternate NAT and an antibody assay. The proportion of donors with confirmed RNAemia and 95% confidence intervals were computed. Of donor samples collected in 2019, 894 yielded valid results, with 6 initially positive, none of which confirmed positive by alternate NAT. Of donor samples collected in 2020, 2562 yielded valid initial NAT results, with 21 (0.8%) initially positive. Among those, 3 were confirmed by alternate NAT, 17 were not confirmed, and 1 had an invalid alternate NAT result. The rate of SARS-CoV-2 RNAemia in deceased tissue donors is approximately 1 per 1000, and it is unknown whether this RNAemia reflects the presence of infectious virus. Given these results, the risk of transmission through tissue is thought likely to be low.

Roles of TGF-β1 in Viral Infection during Pregnancy: Research Update and Perspectives

Transforming growth factor-beta 1 (TGF-β1) is a pleiotropic growth factor playing various roles in the human body including cell growth and development. More functions of TGF-β1 have been discovered, especially its roles in viral infection. TGF-β1 is abundant at the maternal-fetal interface during pregnancy and plays an important function in immune tolerance, an essential key factor for pregnancy success. It plays some critical roles in viral infection in pregnancy, such as its effects on the infection and replication of human cytomegalovirus in syncytiotrophoblasts. Interestingly, its role in the enhancement of Zika virus (ZIKV) infection and replication in first-trimester trophoblasts has recently been reported. The above up-to-date findings have opened one of the promising approaches to studying the mechanisms of viral infection during pregnancy with links to corresponding congenital syndromes. In this article, we review our current and recent advances in understanding the roles of TGF-β1 in viral infection. Our discussion focuses on viral infection during pregnancy, especially in the first trimester. We highlight the mutual roles of viral infection and TGF-β1 in specific contexts and possible functions of the Smad pathway in viral infection, with a special note on ZIKV infection. In addition, we discuss promising approaches to performing further studies on this topic.

Pathogen Exposure in White Whales (Delphinapterus leucas) in Svalbard, Norway

The Svalbard white whale (Delphinapterus leucas) population is one of the smallest in the world, making it particularly vulnerable to challenges such as climate change and pathogens. In this study, serum samples from live captured (2001−2016) white whales from this region were investigated for influenza A virus (IAV) antibodies (Abs) (n = 27) and RNA (n = 25); morbillivirus (MV) Abs (n = 3) and RNA (n = 25); Brucella spp. Abs; and Toxoplasma gondii Abs (n = 27). IAV Abs were found in a single adult male that was captured in Van Mijenfjorden in 2001, although no IAV RNA was detected. Brucella spp. Abs were found in 59% of the sample group (16/27). All MV and T. gondii results were negative. The results show that Svalbard white whales have been exposed to IAV and Brucella spp., although evidence of disease is lacking. However, dramatic changes in climate and marine ecosystems are taking place in the Arctic, so surveillance of health parameters, including pathogens, is critical for tracking changes in the status of this vulnerable population.

Influenza

Annual seasonal influenza epidemics of variable severity caused by influenza A and B virus infections result in substantial disease burden worldwide. Seasonal influenza virus circulation declined markedly in 2020-21 after SARS-CoV-2 emerged but increased in 2021-22. Most people with influenza have abrupt onset of respiratory symptoms and myalgia with or without fever and recover within 1 week, but some can experience severe or fatal complications. Prevention is primarily by annual influenza vaccination, with efforts underway to develop new vaccines with improved effectiveness. Sporadic zoonotic infections with novel influenza A viruses of avian or swine origin continue to pose pandemic threats. In this Seminar, we discuss updates of key influenza issues for clinicians, in particular epidemiology, virology, and pathogenesis, diagnostic testing including multiplex assays that detect influenza viruses and SARS-CoV-2, complications, antiviral treatment, influenza vaccines, infection prevention, and non-pharmaceutical interventions, and highlight gaps in clinical management and priorities for clinical research.

SARS-CoV-2 and seasonal influenza: similarities and disparities

This report describes the differences in disease severity and clinical presentation between hospitalized patients with coronavirus disease 2019 (COVID-19) and others with seasonal influenza. A total of 136 influenza and 152 COVID-19 patients were included. Patients with influenza more frequently had dyspnea (p = 0.004), hypoxemia (p < 0.001), underlying diseases (p = 0.046), and elevated liver enzymes (p = 0.028). In contrast, patients with COVID-19 were overweight (p < 0.001), lymphopenic (p < 0.001), had elevated CRP (p = 0.011), and radiological abnormalities (p < 0.001). Patients with influenza were more severely ill on admission (NEWS > 5) (p < 0.001). However, length of hospital stay, ventilatory support, and 30-day-mortality were similar. Despite differences in clinical presentation and disease severity between influenza and COVID-19 patients, both groups had similar clinical outcomes.

Direct Evidence of Active SARS-CoV-2 Replication in the Intestine

BACKGROUND

Currently, there is no direct evidence to prove the active replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the intestinal tract and relevant pathological changes in the colon and rectum. We investigated the presence of virions and pathological changes in surgical rectal tissues of a patient with clinically confirmed coronavirus disease 2019 (COVID-19) with rectal adenocarcinoma.

METHODS

The clinical data were collected during hospitalization and follow-up of this patient. Quantitative reverse transcriptase-polymerasechain reaction (RT-PCR) was performed on the rectal tissue specimens obtained from surgical resection, succus entericus and intestinal mucosa of ileostomy, and rectal mucosa during follow-up after recovery. Ultrathin sections of surgical samples were observed for SARS-CoV-2 virions using electron microscopy. Histopathological examination was performed using hematoxylin-eosin stain. Immunohistochemical analysis and immunofluorescence were carried out on rectal tissues to evaluate the distribution of SARS-CoV-2 antigen and immune cell infiltrations.

RESULTS

The patient had fever and cough on day 3 postoperatively, was diagnosed with COVID-19 on day 7, and was discharged from the hospital on day 41. RNA of SARS-CoV-2 was detected in surgically resected rectal specimens but not in samples collected 37 days after discharge. Notably, coincident with rectal tissues of surgical specimens testing nucleic acid positive for SARS-CoV-2, typical coronavirus virions in rectal tissue were observed under electron microscopy. Moreover, abundant lymphocytes and macrophages (some were SARS-CoV-2 positive) infiltrating the lamina propria were found with no significant mucosal damage.

CONCLUSIONS

We first report the direct evidence of active SARS-CoV-2 replication in a patient's rectum during the incubation period, which might explain SARS-CoV-2 fecal-oral transmission.

The Epidemiology, Virology, and Pathogenicity of Human Infections with Avian Influenza Viruses

Influenza is a global challenge, and future pandemics of influenza are inevitable. One of the lessons learned from past pandemics is that all pandemic influenza viruses characterized to date possess viral genes originating from avian influenza viruses (AIVs). During the past decades, a wide range of AIVs have overcome the species barrier and infected humans with different clinical manifestations ranging from mild illness to severe disease and even death. Understanding the mechanisms of infection in the context of clinical outcomes, the mechanism of interspecies transmission, and the molecular determinants that confer interspecies transmission is important for pandemic preparedness. Here, we summarize the epidemiology, virology, and pathogenicity of human infections with AIVs to further our understanding of interspecies transmission.

Clinical Effectiveness and Safety of Antivirals for Influenza in Pregnancy

Seasonal influenza epidemics result in substantial health care burden annually. Early initiation of antiviral treatment of influenza has been shown to reduce the risk of complications and duration of illness. Pregnant and postpartum women may be at increased risk for influenza-associated complications; however, pregnant women have been generally excluded from clinical trials of antiviral treatment of influenza. In this review, we summarize the available evidence on the clinical effectiveness and safety of antiviral treatment of pregnant women with influenza. Observational data show a reduction of severe outcomes when pregnant and postpartum women are treated with oseltamivir and other neuraminidase inhibitors without increased risk of adverse maternal, fetal, or neonatal outcomes. Due to lack of safety and efficacy data for baloxavir treatment of pregnant and postpartum women, baloxavir is currently not recommended for use in these populations.

RNAemia Corresponds to Disease Severity and Antibody Response in Hospitalized COVID-19 Patients

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) represents a global health emergency. To improve the understanding of the systemic component of SARS-CoV-2, we investigated if viral load dynamics in plasma and respiratory samples are associated with antibody response and severity of coronavirus disease 2019 (COVID-19). SARS-CoV-2 RNA was found in plasma samples from 14 (44%) out of 32 patients. RNAemia was detected in 5 out of 6 fatal cases. Peak IgG values were significantly lower in mild/moderate than in severe (0.6 (interquartile range, IQR, 0.4–3.2) vs. 11.8 (IQR, 9.9–13.0), adjusted p = 0.003) or critical cases (11.29 (IQR, 8.3–12.0), adjusted p = 0.042). IgG titers were significantly associated with virus Ct (Cycle threshold) value in plasma and respiratory specimens ((ß = 0.4, 95% CI (confidence interval, 0.2; 0.5), p < 0.001 and ß = 0.5, 95% CI (0.2; 0.6), p = 0.002). A classification as severe or a critical case was additionally inversely associated with Ct values in plasma in comparison to mild/moderate cases (ß = −3.3, 95% CI (−5.8; 0.8), p = 0.024 and ß = −4.4, 95% CI (−7.2; 1.6), p = 0.007, respectively). Based on the present data, our hypothesis is that the early stage of SARS-CoV-2 infection is characterized by a primary RNAemia, as a potential manifestation of a systemic infection. Additionally, the viral load in plasma seems to be associated with a worse disease outcome.

Use of SARS-CoV-2-infected deceased organ donors: Should we always "just say no?"

In the context of a rapidly evolving pandemic, multiple organizations have released guidelines stating that all organs from potential deceased donors with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection should be deferred, including from otherwise medically eligible donors found to have mild or asymptomatic SARS-CoV-2 discovered on routine donor screening. In this article, we critically examine the available data on the risk of transmission of SARS-CoV-2 through organ transplantation. The isolation of SARS-CoV-2 from nonlung clinical specimens, the detection of SARS-CoV-2 in autopsy specimens, previous experience with the related coronaviruses SARS-CoV and MERS-CoV, and the vast experience with other common RNA respiratory viruses are all addressed. Taken together, these data provide little evidence to suggest the presence of intact transmissible SARS-CoV in organs that can potentially be transplanted, specifically liver and heart. Other considerations including ethical, financial, societal, and logistical concerns are also addressed. We conclude that, for selected patients with high waitlist mortality, transplant programs should consider accepting heart or liver transplants from deceased donors with SARS-CoV-2 infection.

Detection of Influenza A(H3N2) Virus RNA in Donated Blood

Influenza A virus infection has rarely been documented to cause viremia. In 28 blood donations in Brazil that were deferred because of postdonation information, we identified influenza A(H3N2) virus RNA in 1 donation using metagenomic analysis. Our finding implies theoretical risk for viremia and transfusion transmission.

Diminished immune responses with aging predispose older adults to common and uncommon influenza complications

Influenza (flu) is a serious disease for older adults, with increased severity of infection and greater risk for hospitalization and death. Flu infection is limited to pulmonary epithelial cells, yet there are many systemic symptoms and older adults are more susceptible to flu-related complications. In older adults, flu rarely comes without additional complications and there is a perfect storm for enhanced disease due to multiple factors including existing co-morbidities, plus impaired lung function and dysregulated immune responses that occur with even healthy aging. Commonly, opportunistic secondary bacterial infections prosper in damaged lungs. Intensified systemic inflammation with aging can cause dysfunction in extra-pulmonary organs and tissues such as cardiovascular, musculoskeletal, neuropathologic, hepatic, and renal complications. Often overlooked is the underappreciated connections between many of these conditions, which exacerbate one another when in parallel. This review focuses on flu infection and the numerous complications in older adults associated with diminished immune responses.

Viruses and Autoimmunity: A Review on the Potential Interaction and Molecular Mechanisms

For a long time, viruses have been shown to modify the clinical picture of several autoimmune diseases, including type 1 diabetes (T1D), systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Sjögren’s syndrome (SS), herpetic stromal keratitis (HSK), celiac disease (CD), and multiple sclerosis (MS). Best examples of viral infections that have been proposed to modulate the induction and development of autoimmune diseases are the infections with enteric viruses such as Coxsackie B virus (CVB) and rotavirus, as well as influenza A viruses (IAV), and herpesviruses. Other viruses that have been studied in this context include, measles, mumps, and rubella. Epidemiological studies in humans and experimental studies in animal have shown that viral infections can induce or protect from autoimmunopathologies depending on several factors including genetic background, host-elicited immune responses, type of virus strain, viral load, and the onset time of infection. Still, data delineating the clear mechanistic interaction between the virus and the immune system to induce autoreactivity are scarce. Available data indicate that viral-induced autoimmunity can be activated through multiple mechanisms including molecular mimicry, epitope spreading, bystander activation, and immortalization of infected B cells. Contrarily, the protective effects can be achieved via regulatory immune responses which lead to the suppression of autoimmune phenomena. Therefore, a better understanding of the immune-related molecular processes in virus-induced autoimmunity is warranted. Here we provide an overview of the current understanding of viral-induced autoimmunity and the mechanisms that are associated with this phenomenon.

Macrophage derived TNFα promotes hepatic reprogramming to Warburg-like metabolism

During infection, hepatocytes must undergo a reprioritization of metabolism, termed metabolic reprogramming. Hepatic metabolic reprogramming in response to infection begins within hours of infection, suggesting a mechanism closely linked to pathogen recognition. Following injection with polyinosinic:polycytidylic acid, a mimic of viral infection, a robust hepatic innate immune response could be seen involving the TNFα pathway at 2 h. Repeated doses led to the adoption of Warburg-like metabolism in the liver as determined by in vivo metabolic imaging, expression analyses, and metabolomics. Hepatic macrophages, Kupffer cells, were able to induce Warburg-like metabolism in hepatocytes in vitro via TNFα. Eliminating macrophages in vivo or blocking TNFα in vitro or in vivo resulted in abrogation of the metabolic phenotype, establishing an immune-metabolic axis in hepatic metabolic reprogramming. Overall, we suggest that macrophages, as early sensors of pathogens, instruct hepatocytes via TNFα to undergo metabolic reprogramming to cope with challenges to homeostasis initiated by infection. This work not only addresses a key component of end-organ physiology, but also raises questions about the side effects of biologics in the treatment of inflammatory diseases. KEY MESSAGES: • Hepatocytes develop Warburg-like metabolism in vivo during viral infection. • Macrophage TNFα promotes expression of glycolytic enzymes in hepatocytes. • Blocking this immune-metabolic axis abrogates Warburg-like metabolism in the liver. • Implications for patients being treated for inflammatory diseases with biologics.

A study on mother-to-fetus/infant transmission of influenza A(H7N9) virus: Two case reports and a review of literature

OBJECTIVES

The prevention strategies for mother-to-fetus/infant transmission of H7N9 virus have not been well understood, and the study on this subject will provide further insights.

METHODS

Reverse transcriptase polymerase chain reaction assay was undertaken to detect H7N9 virus in samples from a pregnant women, a postpartum woman, and their fetus/infant. Pathological features of tissues from the dead fetus were evaluated with hematoxylin and eosin staining. Hemagglutination inhibition assay was used to detect virus-specific antibodies. Furthermore, relevant literatures were reviewed and analyzed.

RESULTS

A 28-year-old pregnant woman was hospitalized for H7N9 infection and prescribed with oseltamivir and peramivir for 2 days before admission. The fetal heart beating stopped on day 4, the dead fetus was delivered on day 13, and the woman expired on day 26. All fetal tissues were H7N9 virus-negative. A 28-year-old woman delivered a newborn on December 20, 2016. Five days later, she developed influenza-like symptoms and was confirmed with H7N9 infection. She had close contact with her infant for 9 days. Oseltamivir and peramivir were prescribed within 2 days after illness onset. A throat swab and a pair of serum samples from the infant were all negative for H7N9 virus during 4-week follow-up. In total, ten studies referring to transplacental transmission and four reports on maternal infection of H7N9 virus were reviewed and analyzed.

CONCLUSION

No evidence showed H7N9 virus infection in both fetus and infant. The early administration of neuraminidase inhibitor seemed beneficial in preventing mother-to-fetus/infant transmission of H7N9 virus.

Tissue acylcarnitine status in a mouse model of mitochondrial β-oxidation deficiency during metabolic decompensation due to influenza virus infection

Despite judicious monitoring and care, patients with fatty acid oxidation disorders may experience metabolic decompensation due to infection which may result in rhabdomyolysis, cardiomyopathy, hypoglycemia and liver dysfunction and failure. Since clinical studies on metabolic decompensation are dangerous, we employed a preclinical model of metabolic decompensation due to infection. By infecting mice with mouse adapted influenza and using a pair-feeding strategy in a mouse model of long-chain fatty acid oxidation (Acadvl-/-), our goals were to isolate the effects of infection on tissue acylcarnitines and determine how they relate to their plasma counterparts. Applying statistical data reduction techniques (Partial Least Squares-Discriminant Analysis), we were able to identify critical acylcarnitines that were driving differentiation of our experimental groups for all the tissues studied. While plasma displayed increases in metabolites directly related to mouse VLCAD deficiency (e.g. C16 and C18), organs like the heart, muscle and liver also showed involvement of alternative pathways (e.g. medium-chain FAO and ketogenesis), suggesting adaptive measures. Matched correlation analyses showed strong correlations (r > 0.7) between plasma and tissue levels for a small number of metabolites. Overall, our results demonstrate that infection as a stress produces perturbations in metabolism in Acadvl-/- that differ greatly from WT infected and Acadvl-/- pair-fed controls. This model system will be useful for studying the effects of infection on tissue metabolism as well as evaluating interventions aimed at modulating the effects of metabolic decompensation.

The hidden burden of influenza: A review of the extra-pulmonary complications of influenza infection

Severe influenza infection represents a leading cause of global morbidity and mortality. Although influenza is primarily considered a viral infection that results in pathology limited to the respiratory system, clinical reports suggest that influenza infection is frequently associated with a number of clinical syndromes that involve organ systems outside the respiratory tract. A comprehensive MEDLINE literature review of articles pertaining to extra‐pulmonary complications of influenza infection, using organ‐specific search terms, yielded 218 articles including case reports, epidemiologic investigations, and autopsy studies that were reviewed to determine the clinical involvement of other organs. The most frequently described clinical entities were viral myocarditis and viral encephalitis. Recognition of these extra‐pulmonary complications is critical to determining the true burden of influenza infection and initiating organ‐specific supportive care.

The liver is a metabolic and immunologic organ: A reconsideration of metabolic decompensation due to infection in inborn errors of metabolism (IEM)

Metabolic decompensation in inborn errors of metabolism (IEM) is characterized by a rapid deterioration in metabolic status leading to life-threatening biochemical perturbations (e.g. hypoglycemia, hyperammonemia, acidosis, organ failure). Infection is the major cause of metabolic decompensation in patients with IEM. We hypothesized that activation of the immune system during infection leads to further perturbations in end-organ metabolism resulting in increased morbidity. To address this, we established model systems of metabolic decompensation due to infection. Using these systems, we have described the pathologic mechanisms of metabolic decompensation as well as changes in hepatic metabolic reserve associated with infection. First and foremost, our studies have demonstrated that the liver experiences a significant local innate immune response during influenza infection that modulates hepatic metabolism. Based on these findings, we are the first to suggest that the role of the liver as a metabolic and immunologic organ is central in the pathophysiology of metabolic decompensation due to infection in IEM. The dual function of the liver as a major metabolic regulator and a lymphoid organ responsible for immunosurveillance places this organ at risk for hepatotoxicity. Mobilization of hepatic reserve and the regenerative capacity of a healthy liver compensates for this calculated risk. However, activation of the hepatic innate immune system may be deleterious in IEM. Based on this assertion, strategies aimed at modulating the innate immune response may be a viable target for intervention in the treatment of hepatic metabolic decompensation.

Platelets in Pulmonary Immune Responses and Inflammatory Lung Diseases

Platelets are essential for physiological hemostasis and are central in pathological thrombosis. These are their traditional and best known activities in health and disease. In addition, however, platelets have specializations that broaden their functional repertoire considerably. These functional capabilities, some of which are recently discovered, include the ability to sense and respond to infectious and immune signals and to act as inflammatory effector cells. Human platelets and platelets from mice and other experimental animals can link the innate and adaptive limbs of the immune system and act across the immune continuum, often also linking immune and hemostatic functions. Traditional and newly recognized facets of the biology of platelets are relevant to defensive, physiological immune responses of the lungs and to inflammatory lung diseases. The emerging view of platelets as blood cells that are much more diverse and versatile than previously thought further predicts that additional features of the biology of platelets and of megakaryocytes, the precursors of platelets, will be discovered and that some of these will also influence pulmonary immune defenses and inflammatory injury.

An immunoassay-based reverse-transcription loop-mediated isothermal amplification assay for the rapid detection of avian influenza H5N1 virus viremia

Avian influenza virus (AIV) subtype H5N1 attracts particular consideration because it is a continuous threat to animals and public health systems. The viremia caused by AIV H5N1 infection may increase the risk of blood-borne transmission between humans. Therefore, there is a need to rapidly evaluate and implement screening measures for AIV H5N1 viremia that allows for rapid response to this potentially pandemic threat. The present report describes an immunoassay-based reverse-transcription loop-mediated isothermal amplification (immuno-RT-LAMP) assay for the rapid detection of AIV H5N1 in whole blood samples. Using PCR tubes coated with an H5 subtype monoclonal antibody, AIV H5N1 virions were specifically captured from blood samples. After a thermal lysis step, the released viral N1 gene was exponentially amplified using RT-LAMP on either a real-time PCR instrument for quantitative analysis, or in a water bath system for endpoint analysis. The detection limit of the newly developed immuno-RT-LAMP assay was as low as 1.62×10(1) 50% embryo infectious dose/mL of virus in both regular samples and simulated viremia samples. There were no cross-reactions with non-H5N1 influenza viruses or other avian viruses. The reproducibility of the assay was confirmed using intra- and inter-assay tests with variability ranging from 1.05% to 3.37%. Our results indicate that immuno-RT-LAMP is a novel, effective point-of-care virus identification solution for the rapid diagnosis and monitoring of AIV H5N1 in blood samples.

Geme JW. A 33-month-old with fever and altered mental status

A 33-month-old girl presented with 3 days of fever and 1 day of multiple paroxysmal episodes of screaming with apparent unresponsiveness, flexed lower extremities, clenched hands, and upward eye deviation. These events lasted seconds to a minute at a time and occurred only during sleep. She slept peacefully between episodes and was easily awakened. She had a history of mild speech delay and mild intermittent asthma but was otherwise healthy. She was tired-appearing and fussy on examination with dry mucous membranes, but her examination was otherwise normal. A complete blood count with differential and serum levels of sodium, potassium, chloride, and calcium were normal, but her bicarbonate level was 12 mmol/L. Her fingerstick glucose level was 69 mg/dL. Urine dipstick was notable for large ketones, and a urine drug screen was normal. Cerebrospinal fluid examination yielded 2 white blood cells and 1040 red blood cells/mm(3) with normal chemistries. A computed tomography (CT) scan of her head was unremarkable, and an abdominal ultrasound demonstrated no evidence of intussusception. Over the course of her hospitalization, these paroxysmal episodes persisted, and she subsequently developed mutism, right-sided weakness, and difficulty swallowing liquids. Here we present her case, diagnostic evaluation, and ultimate diagnosis.

Pathogen inactivation technologies for cellular blood components: an update

Nowadays patients receiving blood components are exposed to much less transfusion-transmitted infectious diseases than three decades before when among others HIV was identified as causative agent for the acquired immunodeficiency syndrome and the transmission by blood or coagulation factors became evident. Since that time the implementation of measures for risk prevention and safety precaution was socially and politically accepted. Currently emerging pathogens like arboviruses and the well-known bacterial contamination of platelet concentrates still remain major concerns of blood safety with important clinical consequences, but very rarely with fatal outcome for the blood recipient. In contrast to the well-established pathogen inactivation strategies for fresh frozen plasma using the solvent-detergent procedure or methylene blue and visible light, the bench-to-bedside translation of novel pathogen inactivation technologies for cell-containing blood components such as platelets and red blood cells are still underway. This review summarizes the pharmacological/toxicological assessment and the inactivation efficacy against viruses, bacteria, and protozoa of each of the currently available pathogen inactivation technologies and highlights the impact of the results obtained from several randomized clinical trials and hemovigilance data. Until now in some European countries pathogen inactivation technologies are in in routine use for single-donor plasma and platelets. The invention and adaption of pathogen inactivation technologies for red blood cell units and whole blood donations suggest the universal applicability of these technologies and foster a paradigm shift in the manufacturing of safe blood.

Influenza prevention and treatment in transplant recipients and immunocompromised hosts

The host immune response is critical for the control and clearance of influenza virus after initial infection. Unfortunately, key components of the innate and adaptive responses to influenza are compromised in solid organ and hematopoietic stem cell transplant recipients. As a result, influenza in these key patient populations is associated with prolonged viral shedding, more frequent complications, including bacterial and fungal superinfections and rejection, and increased mortality. While vaccine is the critical prophylaxis strategy in other populations, response rates are diminished, particularly early post-transplant, among immunocompromised patients. Prospective data suggest that antiviral prophylaxis represents an effective and safe alternative to vaccine in patients who would be predicted to have poor responses to influenza vaccine. While there have not been randomized, controlled studies of antiviral therapy completed in solid organ or hematopoietic stem cell patient populations, observational data suggest that early therapy is associated with reduced rates of progression to lower airway involvement, morbidity, and mortality. Further studies are needed to define the optimal regimen, dose, duration, and endpoint to define successful treatment.

Highly pathogenic avian influenza A virus (H5N1) can be transmitted in ferrets by transfusion

Abstracts

Large scale screening of human sera for HCV RNA and GBV-C RNA

North Carolina locates acute HIV cases by pooled nucleic acid testing of HIV-antibody negative serum samples. Here, 224 pools of 80 HIV-negative samples (N = 17,920) were screened for viral RNA from HCV, GBV-C, and influenza A. No evidence of influenza A was found, but HCV and GBV-C were common (1.2% and 1.7% prevalence, respectively), demonstrating the utility of pooled testing in locating individuals that may remain undiagnosed otherwise. By sequencing positive pools, potential transmission clusters may be located as well.

Detection of NH1N1 influenza virus in nonrespiratory sites among children

Among 20 children admitted with laboratory-confirmed influenza, viral RNA was detected in respiratory secretion, stool and blood in 19, 5 and 1 children, respectively. Gastrointestinal symptoms were common but were not associated with viral RNA in stool. nH1N1 viremia was detected, for the first time, in an immunocompetent child.

Neurologic aspects of influenza viruses

Although influenza A and B viruses are primarily known as respiratory viruses and mainly infected only the upper respiratory tract in humans, patients with influenza often develop signs and symptoms that are not due to the respiratory system. Frequently individuals with influenza develop headaches, meningismus, and even seizures in addition to their typical respiratory symptoms. In the past decades, influenza viruses have also been associated with serious non-respiratory signs. The famous 1918 strain of influenza was associated with von Economo's encephalitis lethargica and postencephalitic parkinsonism. In the 1960s influenza virus infections in children were associated with Reye's syndrome characterized often by fatty non-inflammatory hepatic disease and an encephalopathy with marked non-inflammatory cerebral edema. Intermittently children with influenza develop focal myalgia and myositis. Guillain–Barré syndrome was epidemiologically associated with the 1978 killed influenza vaccine but not subsequent vaccines. Although occasional children with influenza have developed encephalopathy, from 2000 through 2004 there was an increase in the number of serious cases of acute necrotizing encephalopathy accompanying infection with the influenza A 2009 strain. The current H5N1 strain of bird influenza occasionally infects humans with a high mortality rate and some appear to have central nervous signs. This chapter explores what is known about these influenza neurologic associations.

Influenza A viruses grow in human pancreatic cells and cause pancreatitis and diabetes in an animal model

Influenza A viruses commonly cause pancreatitis in naturally and experimentally infected animals. In this study, we report the results of in vivo investigations carried out to establish whether influenza virus infection could cause metabolic disorders linked to pancreatic infection. In addition, in vitro tests in human pancreatic islets and in human pancreatic cell lines were performed to evaluate viral growth and cell damage. Infection of an avian model with two low-pathogenicity avian influenza isolates caused pancreatic damage resulting in hyperlipasemia in over 50% of subjects, which evolved into hyperglycemia and subsequently diabetes. Histopathology of the pancreas showed signs of an acute infection resulting in severe fibrosis and disruption of the structure of the organ. Influenza virus nucleoprotein was detected by immunohistochemistry (IHC) in the acinar tissue. Human seasonal H1N1 and H3N2 viruses and avian H7N1 and H7N3 influenza virus isolates were able to infect a selection of human pancreatic cell lines. Human viruses were also shown to be able to infect human pancreatic islets. In situ hybridization assays indicated that viral nucleoprotein could be detected in beta cells. The cytokine activation profile indicated a significant increase of MIG/CXCL9, IP-10/CXCL10, RANTES/CCL5, MIP1b/CCL4, Groa/CXCL1, interleukin 8 (IL-8)/CXCL8, tumor necrosis factor alpha (TNF-α), and IL-6. Our findings indicate that influenza virus infection may play a role as a causative agent of pancreatitis and diabetes in humans and other mammals.

Influenza viral RNA detection in blood as a marker to predict disease severity in hematopoietic cell transplant recipients

Influenza RNA in blood (viremia) was detected in 9 of 79 (11.4%) hematopoietic cell transplant recipients with influenza, and was less frequently observed in patients with upper respiratory tract disease only and more frequently in patients infected with 2009 pandemic influenza A/H1N1 strain (versus seasonal strains). Viremia increased the risk of progression to lower respiratory tract disease (LRD), hypoxemia, respiratory failure, and overall and influenza-related death. Among patients with LRD, viremia was associated with increased hazards of overall and influenza-associated death (hazard ratio 3.5, 1.1–12). Thus, influenza viremia may serve as marker for overall poor outcome.

The National Heart, Lung, and Blood Institute retrovirus epidemiology donor studies (Retrovirus Epidemiology Donor Study and Retrovirus Epidemiology Donor Study-II): twenty years of research to advance blood product safety and availability

The Retrovirus Epidemiology Donor Study (REDS), conducted from 1989 to 2001, and the REDS-II, conducted from 2004 to 2012, were National Heart, Lung, and Blood Institute-funded, multicenter programs focused on improving blood safety and availability in the United States. The REDS-II also included international study sites in Brazil and China. The 3 major research domains of REDS/REDS-II have been infectious disease risk evaluation, blood donation availability, and blood donor characterization. Both programs have made significant contributions to transfusion medicine research methodology by the use of mathematical modeling, large-scale donor surveys, innovative methods of repository sample storage, and establishing an infrastructure that responded to potential emerging blood safety threats such as xenotropic murine leukemia virus-related virus. Blood safety studies have included protocols evaluating epidemiologic and/or laboratory aspects of human immunodeficiency virus, human T-lymphotropic virus 1/2, hepatitis C virus, hepatitis B virus, West Nile virus, cytomegalovirus, human herpesvirus 8, parvovirus B19, malaria, Creutzfeldt-Jakob disease, influenza, and Trypanosoma cruzi infections. Other analyses have characterized blood donor demographics, motivations to donate, factors influencing donor return, behavioral risk factors, donors' perception of the blood donation screening process, and aspects of donor deferral. In REDS-II, 2 large-scale blood donor protocols examined iron deficiency in donors and the prevalence of leukocyte antibodies. This review describes the major study results from over 150 peer-reviewed articles published by these 2 REDS programs. In 2011, a new 7-year program, the Recipient Epidemiology and Donor Evaluation Study-III, was launched. The Recipient Epidemiology and Donor Evaluation Study-III expands beyond donor-based research to include studies of blood transfusion recipients in the hospital setting and adds a third country, South Africa, to the international program.

Prevalence and clinical course of viral upper respiratory tract infections in immunocompromised pediatric patients with malignancies or after hematopoietic stem cell transplantation

BACKGROUND

Respiratory tract infections (RTI) in immunosuppressed pediatric patients with malignancies or after hematopoietic stem cell transplantation (HSCT) are associated with significant morbidity and mortality. Prospective data on the incidence and clinical role of infections by respiratory viruses in this population have been lacking.

METHODS

In this prospective study, 191 children between 0 and 18 years of age were investigated by real-time polymerase chain reaction for the presence of 8 common respiratory virus types in transnasal aspirations. The study included 110 children with leukemia, lymphoma, or solid tumors (subgroup 1); 31 children after HSCT (subgroup 2); and 50 immunocompetent control patients.

RESULTS

In comparison with the control group, immunocompromised children showed a significantly higher incidence of positive virus tests (subgroup 1: 53%; subgroup 2: 81%; controls: 24%; P<0.0001), and more frequently experienced ensuing viral infections in the lower respiratory tract (subgroup 1: 74%; subgroup 2: 88%; controls: 25%; P<0.0001). Sixteen percent of these children had coinfections by 2 or more viruses and revealed more severe respiratory illness.

CONCLUSIONS

The present epidemiologic study on viral upper RTI in immunocompromised children revealed a high virus-associated morbidity which was particularly prominent in HSCT recipients. In these children, detection of viral coinfections was identified as a risk factor for a severe course of lower RTI.

Possible roles of proinflammatory and chemoattractive cytokines produced by human fetal membrane cells in the pathology of adverse pregnancy outcomes associated with influenza virus infection

Pregnant women are at an increased risk of influenza-associated adverse outcomes, such as premature delivery, based on data from the latest pandemic with a novel influenza A (H1N1) virus in 2009-2010. It has been suggested that the transplacental transmission of influenza viruses is rarely detected in humans. A series of our study has demonstrated that influenza virus infection induced apoptosis in primary cultured human fetal membrane chorion cells, from which a factor with monocyte differentiation-inducing (MDI) activity was secreted. Proinflammatory cytokines, such as interleukin (IL)-6, tumor necrosis factor (TNF)-α, and interferon (IFN)-β, were identified as a member of the MDI factor. Influenza virus infection induced the mRNA expression of not only the proinflammatory cytokines but also chemoattractive cytokines, such as monocyte chemoattractant protein (MCP)-1, regulated on activation, normal T-cell expressed and secreted (RANTES), macrophage inflammatory protein (MIP)-1β, IL-8, growth-regulated oncogene (GRO)-α, GRO-β, epithelial cell-derived neutrophil-activating protein (ENA)-78, and interferon inducible protein (IP)-10 in cultured chorion cells. These cytokines are postulated to associate with human parturition. This paper, therefore, reviews (1) lessons from pandemic H1N1 2009 in pregnancy, (2) production of proinflammatory and chemoattractive cytokines by human fetal membranes and their functions in gestational tissues, and (3) possible roles of cytokines produced by human fetal membranes in the pathology of adverse pregnancy outcomes associated with influenza virus infection.

Viral infection triggers rapid differentiation of human blood monocytes into dendritic cells

Surprisingly little is known about the interaction of human blood mononuclear cells with viruses. Here, we show that monocytes are the predominant cell type infected when peripheral blood mononuclear cells are exposed to viruses ex vivo. Remarkably, infection with vesicular stomatitis virus, vaccinia virus, and a variety of influenza A viruses (including circulating swine-origin virus) induces monocytes to differentiate within 18 hours into CD16(-)CD83(+) mature dendritic cells with enhanced capacity to activate T cells. Differentiation into dendritic cells does not require cell division and occurs despite the synthesis of viral proteins, which demonstrates that monocytes counteract the capacity of these highly lytic viruses to hijack host cell biosynthetic capacity. Indeed, differentiation requires infectious virus and viral protein synthesis. These findings demonstrate that monocytes are uniquely susceptible to viral infection among blood mononuclear cells, with the likely purpose of generating cells with enhanced capacity to activate innate and acquired antiviral immunity.

Sensitive detection assays for influenza RNA do not reveal viremia in US blood donors

BACKGROUND

There have been anecdotal reports of influenza viremia since the 1960s. We present an assessment of the prevalence of seasonal and 2009 H1N1 influenza viremia (via RNA testing) in blood donor populations using multiple sensitive detection assays.

METHODS

Several influenza RNA amplification assays, including transcription-mediated amplification (TMA) and 2 reverse-transcription polymerase chain reaction (RT-PCR) assays, were evaluated and used to test donor samples. Retrospective samples from 478 subjects drawn at sites with high influenza activity were tested. Prospective samples were collected from 1004 blood donors who called their donation center within 3 days of donation complaining of influenza-like illness (ILI). The plasma collected on the day of donation for these subjects was tested.

RESULTS

Of the repository samples, 2 of 478 plasma samples were initially reactive but not repeat reactive by influenza TMA. Of blood donors reporting ILI symptoms postdonation, 1 of 1004 samples was TMA initially reactive but not repeat reactive; all samples were nonreactive by RT-PCR testing.

CONCLUSIONS

Targeting blood donor populations most likely to have influenza infection, we failed to detect influenza RNA in 1482 donor samples, with most tested by 3 different RNA assays. Seasonal influenza does not appear to pose a significant contamination threat to the blood supply.

Stability and infectivity of novel pandemic influenza A (H1N1) virus in blood-derived matrices under different storage conditions

Background

Influenza A virus has been detected in the blood of some infected individuals, and may pose a safety concern for collection, handling and transport of specimens for epidemiological and public health investigations if infectious virus is present in samples. Furthermore the effect of storage on virus stability and infectivity has not been well studied.

Methods

We examined the stability of novel pandemic influenza A (H1N1) virus RNA when the virus was stored in phosphate buffered saline (PBS), plasma, or buffy coated blood at either room temperature or 4°C using a sensitive Taqman RT-PCR assay. We also investigated virus infectivity using the EID₅₀ assay when virus was stored in PBS, plasma, or buffy coats isolated from blood at 4°C.

Results

Viral RNA stability was affected by the matrix used for storage. The recovery of viral RNA was highest when virus was stored in PBS with lower amounts being recovered from plasma and buffy coats at either room temperature or 4°C. Incubation time did not appear to be a major factor for viral RNA stability, although there was gradual decline after longer periods post-incubation. Both sample matrix and incubation time affected virus infectivity. The decay in virus infectivity was greatest in PBS followed by buffy coats and plasma. Virus infectivity was abolished in buffy coats at day 20 post-incubation when virus concentrations were low.

Conclusion

These data indicate that encapsidated viral RNA was stable overall in all three liquid matrices at room temperature or 4°C although it was most stable in PBS; virus infectivity in buffy coats at 4°C decayed in a time dependent manner while it remained unchanged in plasma. These findings have implications for storage, handling and transport of blood derived samples from influenza patients for epidemiological and laboratory investigations. It should be noted that there is little known about influenza viremia, and whether influenza viruses can be transmitted by blood or blood derived samples.

Clinical and virological factors associated with viremia in pandemic influenza A/H1N1/2009 virus infection

BACKGROUND

Positive detection of viral RNA in blood and other non-respiratory specimens occurs in severe human influenza A/H5N1 viral infection but is not known to occur commonly in seasonal human influenza infection. Recently, viral RNA was detected in the blood of patients suffering from severe pandemic influenza A/H1N1/2009 viral infection, although the significance of viremia had not been previously studied. Our study aims to explore the clinical and virological factors associated with pandemic influenza A/H1N1/2009 viremia and to determine its clinical significance.

METHODOLOGY/PRINCIPAL FINDINGS

Clinical data of patients admitted to hospitals in Hong Kong between May 2009 and April 2010 and tested positive for pandemic influenza A/H1N1/2009 was collected. Viral RNA was detected by reverse-transcription polymerase chain reactions (RT-PCR) targeting the matrix (M) and HA genes of pandemic influenza A/H1N1/2009 virus from the following specimens: nasopharyngeal aspirate (NPA), endotracheal aspirate (ETA), blood, stool and rectal swab. Stool and/ or rectal swab was obtained only if the patient complained of any gastrointestinal symptoms. A total of 139 patients were included in the study, with viral RNA being detected in the blood of 14 patients by RT-PCR. The occurrence of viremia was strongly associated with a severe clinical presentation and a higher mortality rate, although the latter association was not statistically significant. D222G/N quasispecies were observed in 90% of the blood samples.

CONCLUSION

Presence of pandemic influenza A/H1N1/2009 viremia is an indicator of disease severity and strongly associated with D222G/N mutation in the viral hemagglutinin protein.

Evidence of viremia in 2 cases of severe pandemic influenza A H1N1/09

The recent pandemic of the 2009 pandemic influenza A (H1N1) infrequently caused severe disease. We describe 2 cases of 2009 H1N1 influenza with rapid progression resulting in respiratory failure and need for prolonged intensive care support. Real-time polymerase chain reaction amplification for influenza A (using a Centers for Disease Control and Prevention protocol) and the 2009 H1N1 influenza (using an in-house protocol) was performed on serial respiratory and serum specimens from both patients collected over 3 weeks. Both patients repeatedly demonstrated 2009 H1N1 influenza in respiratory specimens. Evidence of influenza A viremia was also detected in both cases, although it was confirmed as 2009 H1N1 influenza in only one. The presence of viremia in cases of severe 2009 H1N1 influenza has potential prognostic and therapeutic implications. Detection of viremia may be useful as a predictive marker for severe disease. Antiviral agents with low serum levels may be ineffective if administered to patients with influenza viremia.