Prospects of RNA interference therapy in respiratory viral diseases: update 2006

Respiratory viruses, such as influenza, parainfluenza and respiratory syncytial virus (RSV), claim millions of lives annually. At present, there is no completely effective vaccine or drug against these highly mutable RNA viruses. Passive antibody therapies for RSV, despite their limited application and staggering cost, enjoy a virtual monopoly in a multibillion-dollar global market. Recently, however, pioneering discoveries have launched RNA interference as a novel, nucleic acid-based therapy against viral pathogens. Specifically, small interfering RNAs (siRNAs) offered protection against respiratory syncytial virus, parainfluenza and influenza. siRNA against RSV has entered Phase I clinical trials in humans, and preliminary reports are promising. If appropriately formulated for improved specificity, delivery and pharmacokinetics, siRNAs may indeed become effective antivirals in the clinics of the future. This paper provides an overview of the prospects and hurdles facing the antiviral siRNA drugs, with special emphasis on RSV.     

Pneumopathies communautaires d'origine virale en réanimation chez l'adulte immunocompétent

There is little data available in the literature on the incidence, etiology and the consequences of community-acquired severe viral pneumonia in the non-immunodeficient adult. In most studies, the viral etiology has not been investigated. The results of studies carried out over the last ten years show a frequency of between 1 and 13.6%. Diagnosis is frequently based on serological testing, but full testing is only carried out in under 50% of cases. In France, respiratory viruses are mainly influenza virus (40–50%), followed by respiratory syncytial virus (RSV: 14%), parainfluenza virus (20–30%), and adenovirus (12–14%). Viruses responsible for pulmonary infection introduced via the hematogenic pathway (varicella-zoster, Epstein-Barr, measles, enterovirus, etc.) are less common, but easier to diagnose. Epidemiological studies should include a thorough investigation of the viral etiology, with for the majority of viruses, viral antigen detection by IF or Elisa, or viral isolation and culture. Serological testing is useful for certain viruses (measles, Epstein-Barr, Hantavirus). Molecular biological techniques are in the process of being assessed. Routinely, the lack of efficient therapeutic agents to treat cases of severe viral pneumonia limits the interest of an etiological approach. RSV infection can be easily and inexpensively diagnosed by viral antigen detection, or viral isolation and culture, but the diagnosis for influenza must be made early after the onset of symptoms, otherwise serological diagnosis may be made a posterior. The aim of such research is to introduce suitable anti-influenza prophylaxis for at-risk subjects, and hygienic measures to limit RSV cross-transmission.     

直接免疫荧光法对多种呼吸道病毒检测的临床意义

目的为临床提供一种快速诊断呼吸道病毒感染的方法。方法采用直接荧光免疫法检测呼吸道分泌物的合胞病毒、腺病毒、流感病毒A、流感病毒B及副流感病毒1、2、3型。结果对195例呼吸道感染者的鼻咽分泌物标本采用直接荧光免疫法进行病毒原检测，结果显示本地区病毒感染率为57．94％，病毒原以呼吸道合胞病毒为主，副流感病毒1、3型次之，感染以冬季好发。结论该法具有快速、简便、特异性高等优点，对确定临床呼吸道病毒感染是一种非常好的方法。直接荧光免疫法操作简便，费用较低，适合基层医院推广使用。     

Surveillance of viral respiratory tract infections over a one year period in mainly hospitalized Austrian infants and children by a rapid enzyme-linked immunosorbent assay diagnosis

In order to obtain more information on viral respiratory tract infections in Austrian infants and children, nasopharyngeal secretions from 1432 infants and children, collected from October 1984 to October 1985, were screened for the presence of respiratory syncytial virus (RSV), adenoviruses, parainfluenza virus type 1, 2, and 3, and influenza viruses type A and B, by enzyme-linked immunosorbent assay (ELISA). The results obtained were analyzed with respect to incidence, seasonal distribution and clinical syndromes associated with the different viral pathogens investigated and also with the practicability of ELISA diagnostics over long distances. A viral etiology of acute respiratory tract infection was confirmed in 372 (26%) infants. RSV was detected in 286 (20%) of the nasal secretions and was thus the most frequently encountered agent. RSV infections occurred mainly in the winter months and were often associated with bronchitis, bronchiolitis, and pneumonia. Only sporadic infections were found with one of the other viruses investigated.     

Anti-RNA virus activity of polyoxometalates.

The anti-RNA virus activity of polyoxometalates (POM) is reviewed, with a special emphasis on the anti-respiratory virus activities. There are many causative agents of acute viral respiratory infections; and it is rather difficult to identify the relevant agent in a given case by rapid clinical means. During acute progress of infection before the definitive diagnosis is obtained physicians need to prescribe certain broad spectrum anti-viral drugs. A titanium containing polyoxotungstate, PM-523 exhibited potent anti-influenza virus (FluV) A and anti-respiratory syncytial virus (RSV) activities in vitro. Therapeutic effect of FluV A infected mice with aerosol inhalation of PM-523 was proven. A vanadium substituted polyoxotungstate, PM-1001 has antiviral activity against FluV A, RSV, parainfluenza virus (PfluV) type 2, Dengue fiver virus, HIV-1 and SARS coronavirus in vitro. Thus, POMs have been proven to be broad spectrum and non-toxic anti-RNA virus agents in both in vitro and in vivo experiments and are promising candidates for first-line therapeutics in acute respiratory diseases.     

海岛地区婴幼儿呼吸道感染的病原学研究

目的 探讨海岛地区婴幼儿急性呼吸道感染的病毒病原.方法 采取211例急性呼吸道感染患儿的痰液做病毒检测.结果 病毒感染35例,其中呼吸道合胞病毒(RSV)感染20例(9.5%),流感病毒感染6例(2.8%),腺病毒9例(4-3%),副流感病毒Ⅲ型4例(1.9%),副流感病毒Ⅰ、Ⅱ型各2例(1%).结论 RSV感染仍是海岛婴幼儿急性呼吸道病毒感染最常见的病原,病毒病原的诊断可为临床诊断和治疗提供可靠的依据.     

Clinical features of pneumonia associated with influenza virus infection

The history of influenza pandemics was reviewed and clinical manifestations of pneumonia associated with influenza virus infections are described. Several types of pneumonia associated with the influenza virus infection have been reported: 1) influenza complicated by secondary bacterial pneumonia, 2) primary influenza virus pneumonia, 3) combined influenza virus and bacterial pneumonia. Secondary bacterial pneumonia often produces a syndrome that is clinically distinguishable from that of primary viral pneumonia. In primary influenza virus pneumonia, chest roentgenography revealed bilateral infiltrations but no consolidation. Histologically, diffuse alveolar damage and hemorrhagic bronchiolitis were frequently observed in primary influenza virus pneumonia, in which case the prognosis was the worst. Although rare, the possibility of bronchiolitis obliterans organizing pneumonia associated with influenza virus infection should be recognized. H. influenzae, S. pneumoniae, or S. aureus were frequently associated with influenza viral infection, and treatment against these bacteria should be considered.     

Pneumonia associated with influenza virus infection

The history of influenza pandemics was reviewed and clinical manifestations of pneumonia associated with influenza virus infections are described and several typical cases are presented. Several types of pneumonia associated with the influenza virus infection have been reported: 1) influenza complicated by secondary bacterial pneumonia, 2) primary influenza virus pneumonia, 3) combined influenza virus and bacterial pneumonia. Secondary bacterial pneumonia often produces a syndrome that is clinically distinguishable from that of primary viral pneumonia. In primary influenza virus pneumonia, chest roentgenography revealed bilateral infiltrations but no consolidation. Histologically, diffuse alveolar damage and hemorrhagic bronchiolitis were frequently observed in primary influenza virus pneumonia, in which case the prognosis was the worst. Although rare, the possibility of cryptogenic organizing pneumonia associated with influenza virus infection should be recognized. H. influenzae, S. pneumoniae, or S. aureus were frequently associated with influenza viral infection, and treatment against these bacteria should be considered.     

Bench-to-bedside review: Bacterial pneumonia with influenza - pathogenesis and clinical implications

Seasonal and pandemic influenza are frequently complicated by bacterial infections, causing additional hospitalization and mortality. Secondary bacterial respiratory infection can be subdivided into combined viral/bacterial pneumonia and post-influenza pneumonia, which differ in their pathogenesis. During combined viral/bacterial infection, the virus, the bacterium and the host interact with each other. Post-influenza pneumonia may, at least in part, be due to resolution of inflammation caused by the primary viral infection. These mechanisms restore tissue homeostasis but greatly impair the host response against unrelated bacterial pathogens. In this review we summarize the underlying mechanisms leading to combined viral/bacterial infection or post-influenza pneumonia and highlight important considerations for effective treatment of bacterial pneumonia during and shortly after influenza.     

Differential inhibitory effects of sulfated polysaccharides and polymers on the replication of various myxoviruses and retroviruses, depending on the composition of the target amino acid sequences of the viral envelope glycoproteins.

Sulfated polysaccharides (i.e., dextran sulfate) and sulfated polymers (i.e., sulfated polyvinylalcohol and sulfated copolymers of acrylic acid with vinylalcohol) were found to be potent and selective inhibitors of the replication of respiratory syncytial virus (RSV) and influenza virus type A (influenza A virus) but not of other myxoviruses (parainfluenza 3, measles, and influenza B viruses). The compounds were also inhibitory to human immunodeficiency virus type 1 (HIV-1) and HIV-2 and simian immunodeficiency virus but not simian AIDS-related virus. The mode of antiviral action of the sulfated polysaccharides and polymers can be attributed to an inhibition of virus binding to the cells (HIV-1), inhibition of virus-cell fusion (influenza A virus), or inhibition of both virus-cell binding and fusion (RSV). The fact that the sulfated polysaccharides and polymers are inhibitory to some myxoviruses and retroviruses but not to others seems to depend on the composition of the amino acid sequences of the viral envelope glycoproteins that are involved in virus-cell binding and fusion. All myxoviruses and retroviruses that are sensitive to the sulfated polysaccharides and polymers share a tripeptide segment (Phe-Leu-Gly). This tripeptide segment may be involved either directly (as a target sequence) or indirectly in the inhibitory effects of the compounds on virus-cell binding and fusion.     

Guideline for prevention of nosocomial pneumonia. Centers for Disease Control and Prevention

Pneumonia is the second most common nosocomial infection in the United States and is associated with substantial morbidity and mortality. Most patients with nosocomial pneumonia are those with extremes of age, severe underlying disease, immunosuppression, depressed sensorium, and cardiopulmonary disease, and those who have had thoracoabdominal surgery. Although patients with mechanically assisted ventilation do not comprise a major proportion of patients with nosocomial pneumonia, they have the highest risk of developing the infection. Most bacterial nosocomial pneumonias occur by aspiration of bacteria colonizing the oropharynx or upper gastrointestinal tract of the patient. Intubation and mechanical ventilation greatly increase the risk of nosocomial bacterial pneumonia because they alter first-line patient defenses. Pneumonias due to Legionella spp., Aspergillus spp., and influenza virus are often caused by inhalation of contaminated aerosols. Respiratory syncytial virus (RSV) infection usually follows viral inoculation of the conjunctivae or nasal mucosa by contaminated hands. Traditional preventive measures for nosocomial pneumonia include decreasing aspiration by the patient, preventing cross-contamination or colonization via hands of personnel, appropriate disinfection or sterilization or respiratory therapy devices, use of available vaccines to protect against particular infections, and education of hospital staff and patients. New measures under investigation involve reducing oropharyngeal and gastric colonization by pathogenic microorganisms.     

Influenza A pneumonia with rhabdomyolysis

Influenza A pneumonia accounts for a significant number of the community-acquired pneumonias in the United States. While myalgia is a common complaint in influenza A infection, few cases of rhabdomyolysis associated with this virus have been described. Although it has been recently recognized that rhabdomyolysis complicating certain bacterial pneumonias has important prognostic implications, rhabdomyolysis in the setting of influenza A pneumonia does not appear to carry the same prognostic significance.     

Comparison of direct immunofluorescence of exfoliated cells (DIF), tissue culture immunofluorescence (TCIF) and conventional virus isolation (CVI) for the diagnosis of respiratory virus infections

Direct immunofluorescent staining (DIF) of exfoliated cells and immunofluorescent staining of infected tissue culture cells (TCIF) are superior to conventional virus isolation (CVI) techniques for the diagnosis of respiratory virus infections. Out of 197 specimens from patients with respiratory syncytial virus (RSV), influenza or parainfluenza virus, measles, adenovirus or cytomegalovirus (CMV) infections, DIF recognised 84%, TCIF 82% and CVI only 42%. DIF and TCIF were particularly useful for the diagnosis of RSV and parainfluenza virus infections, and the optimal specimen for diagnosis was nasopharyngeal aspirate.     

常德地区小儿呼吸道病毒性感染病原学分析

目的探讨常德地区小儿呼吸道病毒性感染的病原学概况,为临床诊治工作提供参考.方法应用免疫荧光法检测患儿早期咽拭子标本中7项病毒[合胞病毒(RSV)、腺病毒(ADV )、流感病毒 A (FLuA )、流感病毒B(FLuB)、副流感病毒1(PIV1)、副流感病毒2(PIV2)、副流感病毒3(PIV3)],以了解病原学分布.结果从2778例患儿咽拭子标本中,检出相关病毒阳性1260例,总阳性率为45.4%.含单项病毒感染占89.0%,2项混合感染占11.0%.单一病毒感染中 RSV 占首位(57.40%),其余依次为 PIV1(11.31%)、PIV2(8.91%)、FLuB(6.33%)、ADV(5.97%)、PIV3(5.53%)、FLuA(4.55%).结论RSV 、PIV1、PIV2为常德地区致小儿呼吸道感染的主要流行病原体.对疑似病例早期进行7项呼吸道病毒检测,尽早为临床提供病原学诊断,使患儿得到及时诊治.     

Detection of multiple viral agents in nasopharyngeal specimens yielding respiratory syncytial virus (RSV). An assessment of diagnostic strategy and clinical significance

A retrospective study of 6 years (1981-1987) experience with clinical specimens of pediatric patients submitted for identification of respiratory viruses was undertaken to determine the prevalence of multiple viral isolates and to assess the impact of dual infections on severity of clinical disease. Respiratory Syncytial Virus (RSV), the most frequently identified agent, was detected in cell culture and/or by immunofluorescence (IF) in 666 of 2,415 specimens examined. A second virus was isolated in cell cultures from 51 of the 666 specimens (7.6%). Cytomegalovirus, rhinoviruses, adenoviruses, influenza and parainfluenza viruses, echoviruses, vaccine strain polio viruses, and herpes simplex virus were identified with RSV. The diagnosis of a dual viral infection would have been missed in 37 of 51 instances (79%) had rapid diagnosis for RSV been employed without inoculation of cell cultures. Demographics and clinical presentations were similar in patients with dual infections or RSV alone. A case-control study comparing patients with dual isolates and patients with RSV alone to determine the effect of multiple viral infections on severity of disease revealed no significant difference. The combined use of rapid methods and isolation in culture provides more complete viral diagnosis and could have an impact on the choice of antiviral agents and the institution of appropriate infection control measures.     

不同呼吸道病毒在武汉地区儿童中的流行特征分析

目的：了解腺病毒（ADV）、呼吸道合胞病毒（RSV）、甲型流感病毒（FluA）、乙型流感病毒（FluB）、副流感病毒1型（PIV1）、副流感病毒2型（PIV2）和副流感病毒3型（PIV3）在武汉地区儿童中的流行特征。方法收集2011年1月至2012年12月本院儿科收治的呼吸道感染患儿上述7种病毒直接免疫荧光法检测结果资料,分析不同病毒的检测结果及流行特征。结果共检测患儿标本5925例,检出阳性标本1657例,总阳性率为28．0％。RSV阳性检出率最高,为17．4％,PIV2阳性检出率最低,为0．2％。总体而言,2月份病毒阳性检出率最高,为54．0％,10月份最低,为15．4％。RSV和 PIV3在0～1岁患儿中的阳性检出率明显高于大于1岁的患儿（ P＜0．05）,ADV、FluA和FluB在0～1岁患儿中的阳性检出率明显低于大于1岁的患儿（P＜0．05）,PIV1和PIV2阳性检出率组间比较差异则无统计学意义（P＞0．05）。结论 RSV是导致武汉地区儿童呼吸道感染的主要病原体;病毒感染流行性有明显的季节特征,2月份是病毒感染流行性最强的月份;不同年龄儿童对各种病毒存在不同的易感性。     

Viral pneumonias. A diagnostic and therapeutic challenge

Viral pneumonias are both a diagnostic and a therapeutic challenge for primary care physicians. The illness should be suspected when an upper respiratory tract infection progresses to include dyspnea and cyanosis. Rapid diagnostic tests are now available to detect most of the viruses that cause pneumonias. Fortunately, viral pneumonias usually resolve without specific antiviral therapy; however, ribavirin is indicated for respiratory syncytial virus pneumonia in children and ganciclovir sodium (Cytovene) for cytomegalovirus pneumonia in immunocompromised patients. Acyclovir (Zovirax) is indicated for pneumonias due to herpes simplex virus and varicella-zoster virus infections. A high index of suspicion for bacterial superinfections is essential to reduce the risk of death from this complication.     

Viral infections of the respiratory tract in patients with cystic fibrosis

The role of viruses and bacteria in the development of respiratory tract infections causing acute deteriorations in lung function in patients with cystic fibrosis (CF) was investigated. Over a period of 30 months, 29 viral respiratory diseases were proven serologically by testing 275 sporadically collected sera from 75 patients with cystic fibrosis. The influenza A virus was the most frequent responsible viral pathogen (11 × ), followed by adenovirus (8 × ), influenza B virus (5 × ), parainfluenza virus type 3 (3 × ), parainfluenza virus type 1 and respiratory syncytial virus (RSV) (each of 1 × ). There was no serological evidence for infections with parainfluenza virus type 2, Mycoplasma pneumoniae or Coxiella burnetii. Deterioration of the clinical condition was found in 78% of the viral infections leading in 70% to hospital admission. Patients with cystic fibrosis and viral respiratory illnesses showed significantly more admissions to the hospital (3·2 ± 2·7) with a longer stay (90·6 ± 99·6 days). Nearly all viral episodes (93%) were accompanied or followed by a significant change of the microbial flora in the sputum especially by colonisation with Pseudomonas aeruginosa, Staphylococcus aureus and Haemophilus influenzae. Seventy-two per cent of the viral infections occurred at home and 28% seemed to be hospital acquired. Our study emphasises the importance of improving antibacterial therapy at home to reduce the number of hospital admissions. Efforts for prophylaxis by vaccination or the use of chemotherapeutic agents should be made for the patients with cystic fibrosis.     

Potent anti-influenza activity of cyanovirin-N and interactions with viral hemagglutinin

The novel antiviral protein cyanovirin-N (CV-N) was initially discovered based on its potent activity against the human immunodeficiency virus (HIV). Subsequent studies identified the HIV envelope glycoproteins gp120 and gp41 as molecular targets of CV-N. More recently, mechanistic studies have shown that certain high-mannose oligosaccharides (oligomannose-8 and oligomannose-9) found on the HIV envelope glycoproteins comprise the specific sites to which CV-N binds. Such selective, carbohydrate-dependent interactions may account, at least in part, for the unusual and unexpected spectrum of antiviral activity of CV-N described herein. We screened CV-N against a broad range of respiratory and enteric viruses, as well as flaviviruses and herpesviruses. CV-N was inactive against rhinoviruses, human parainfluenza virus, respiratory syncytial virus, and enteric viruses but was moderately active against some herpesvirus and hepatitis virus (bovine viral diarrhea virus) strains (50% effective concentration [EC(50)] = approximately 1 micro g/ml) while inactive against others. Remarkably, however, CV-N and related homologs showed highly potent antiviral activity against almost all strains of influenza A and B virus, including clinical isolates and a neuraminidase inhibitor-resistant strain (EC(50) = 0.004 to 0.04 micro g/ml). When influenza virus particles were pretreated with CV-N, viral titers were lowered significantly (>1,000-fold). Further studies identified influenza virus hemagglutinin as a target for CV-N, showed that antiviral activity and hemagglutinin binding were correlated, and indicated that CV-N's interactions with hemagglutinin involved oligosaccharides. These results further reveal new potential avenues for antiviral therapeutics and prophylaxis targeting specific oligosaccharide-comprised sites on certain enveloped viruses, including HIV, influenza virus, and possibly others.