Clinical review: update of avian influenza A infections in humans

Immunogenicity and Efficacy of Vaccination in People Living with Human Immunodeficiency Virus

People living with HIV (PLWH) remain at high risk of mortality and morbidity from vaccine-preventable diseases, even though antiretroviral therapy (ART) has restored life expectancy and general well-being. When, which, and how many doses of vaccine should be administered over the lifetime of PLWH are questions that have become clinically relevant. Immune responses to most vaccines are known to be impaired in PLWH. Effective control of viremia with ART and restored CD4+ T-cell count are correlated with an improvement in responsiveness to routine vaccines. However, the presence of immune alterations, comorbidities and co-infections may alter it. In this article, we provide a comprehensive review of the literature on immune responses to different vaccines in the setting of HIV infection, emphasizing the potential effect of HIV-related factors and presence of comorbidities in modulating such responses. A better understanding of these issues will help guide vaccination and prevention strategies for PLWH.

CRISPR/Cas13a combined with hybridization chain reaction for visual detection of influenza A (H1N1) virus

This study provides proof of concept of a colorimetric biosensor for influenza H1N1 virus assay based on the CRISPR/Cas13a system and hybridization chain reaction (HCR). Target RNA of influenza H1N1 virus activated the trans-cleavage activity of Cas13a, which cleaved the special RNA sequence (-UUU-) of the probe, further initiating HCR to copiously generate G-rich DNA. Abundant G-quadruplex/hemin was formed in the presence of hemin, thus catalyzing a colorimetric reaction. The colorimetric biosensor exhibited a linear relationship from 10 pM to 100 nM. The detection limit was 0.152 pM. The biosensor specificity was excellent. This new and sensitive detection method for influenza virus is a promising rapid influenza diagnostic test.

Rapid and quantitative detection of zoonotic influenza A virus infection utilizing coumarin-derived dendrimer-based fluorescent immunochromatographic strip test (FICT)

Great efforts have been made to develop robust signal-generating fluorescence materials which will help in improving the rapid diagnostic test (RDT) in terms of sensitivity and quantification. In this study, we developed coumarin-derived dendrimer-based fluorescent immunochromatographic strip test (FICT) assay with enhanced sensitivity as a quantitative diagnostic tool in typical RDT environments. The accuracy of the proposed FICT was compared with that of dot blot immunoassay techniques and conventional RDTs. Through conjugation of coumarin-derived dendrimers with latex beads, fluorescent emission covering broad output spectral ranges was obtained which provided a distinct advantage of easy discrimination of the fluorescent emission of the latex beads with a simple insertion of a long-pass optical filter away from the excitation wavelength. The newly developed FICT assay was able to detect 100 ng/10 μL of influenza A nucleoprotein (NP) antigen within 5 minutes, which corresponded to 2.5-fold higher sensitivity than that of the dot blot immunoassay or conventional RDTs. Moreover, the FICT assay was confirmed to detect at least four avian influenza A subtypes (H5N3, H7N1, H7N7, and H9N2). On applying the FICT to the clinical swab samples infected with respiratory viruses, our FICT assay was confirmed to differentiate influenza H1N1 infection from other respiratory viral diseases. These data demonstrate that the proposed FICT assay is able to detect zoonotic influenza A viruses with a high sensitivity, and it enables the quantitation of the infection intensity by providing the numerical diagnostic values; thus demonstrating enhanced detectability of influenza A viruses.

Progress and hurdles in the development of influenza virus-like particle vaccines for veterinary use

Virus-like particles (VLPs), which resemble infectious virus particles in structure and morphology, have been proposed to provide a new generation of vaccine candidates against various viral infections. As effective immunogens, characterized by high immunogenicity and safety, VLPs have been employed in the development of human influenza vaccines. Recently, several influenza VLP vaccines have been developed for veterinary use and successfully evaluated in swine, canine, duck, and chicken models. These VLP vaccine candidates induced protective immune responses and enabled serological differentiation between vaccinated and infected animals in conjunction with a diagnostic test. Here, we review the current progress of influenza VLP development as a next-generation vaccine technology in the veterinary field and discuss the challenges and future direction of this technology.

Role of Fat-Soluble Vitamins A and D in the Pathogenesis of Influenza: A New Perspective

Reduced exposure to solar radiation, leading to a deficiency of vitamin D and hence impaired innate immunity, has been suggested as a trigger for influenza viral replication and as an explanation of seasonal influenza. Although this hypothesis accounts for many unexplained facts about the epidemiology of influenza, gaps remain in understanding the pathogenesis and manifestations of the disease. Several observations suggest a role for vitamin A compounds (retinoids) in the disease. This paper presents a new model of the etiopathogenesis of influenza, suggesting that host resistance and susceptibility depend importantly on the ratio of vitamin D to vitamin A activity. Retinoid concentrations within normal physiological limits appear to inhibit influenza pathogenesis whereas higher background concentrations (i.e., very low vitamin D : A ratios) increase the risk of severe complications of the disease. There is also evidence that influenza-induced or preexisting liver disease, diabetes, and obesity worsen the severity of infection, possibly via liver dysfunction and alterations in retinoid metabolism. The model could be tested by determining the presence of retinoids in the secretions of patients with influenza and by studies of retinoid profiles in patients and controls. Potential strategies for prevention and treatment are discussed.

Initial infectious dose dictates the innate, adaptive, and memory responses to influenza in the respiratory tract

Factors from the virus and the host contribute to influenza virus pathogenicity and to the development of immunity. This study thoroughly examined the effects of an initial infectious dose of virus and unveiled new findings concerning the antiviral and inflammatory responses, innate and adaptive immunity, memory responses, and protection against secondary heterologous infection. Our results demonstrated that the initial infectious dose significantly affects the gene expression of antiviral (IFN-β) and inflammatory (TNF-α, IL-6, IL-1β) cytokines and of enzymes involved in nitrosative/oxidative stress (iNOS, HO-1, NQO1) early in the response to influenza. This response correlated with significantly increased recruitment of innate immune cells into the lungs of infected mice. We showed that this response also alters the subsequent accumulation of activated IFN-γ(+) CD44(hi) CD62L(lo) influenza-specific CD8(+) T cells into the lungs of infected mice through increased T cell-recruiting chemokine gene expression (CCL3, CCL4, CCL5, CXCL10). Furthermore, we demonstrated that the initial infectious dose determines the generation and the distribution of memory CD8(+) T cell subsets without affecting trafficking mechanisms. This impacted on immune protection against heterologous infection. Lastly, we showed that the effects on innate and adaptive immunity were not dependent on influenza strain or on the genetic background of the host. Collectively, our data show for the first time and in detail that the initial infectious dose of influenza determines the development of several aspects of antiviral immunity. This study provides new insights on virus-host interaction in the generation of the global immune response to influenza.

Dose-response assessment for influenza A virus based on data sets of infection with its live attenuated reassortants

Reported data sets on infection of volunteers challenged with wild-type influenza A virus at graded doses are few. Alternatively, we aimed at developing a dose-response assessment for this virus based on the data sets for its live attenuated reassortants. Eleven data sets for live attenuated reassortants that were fit to beta-Poisson and exponential dose-response models. Dose-response relationships for those reassortants were characterized by pooling analysis of the data sets with respect to virus subtype (H1N1 or H3N2), attenuation method (cold-adapted or avian-human gene reassortment), and human age (adults or children). Furthermore, by comparing the above data sets to a limited number of reported data sets for wild-type virus, we quantified the degree of attenuation of wild-type virus with gene reassortment and estimated its infectivity. As a result, dose-response relationships of all reassortants were best described by a beta-Poisson model. Virus subtype and human age were significant factors determining the dose-response relationship, whereas attenuation method affected only the relationship of H1N1 virus infection to adults. The data sets for H3N2 wild-type virus could be pooled with those for its reassortants on the assumption that the gene reassortment attenuates wild-type virus by at least 63 times and most likely 1,070 times. Considering this most likely degree of attenuation, 10% infectious dose of H3N2 wild-type virus for adults was estimated at 18 TCID50 (95% CI = 8.8-35 TCID50). The infectivity of wild-type H1N1 virus remains unknown as the data set pooling was unsuccessful.

Hemagglutinin from the H5N1 virus activates Janus kinase 3 to dysregulate innate immunity

Highly pathogenic avian influenza viruses (HPAIVs) cause severe disease in humans. There are no effective vaccines or antiviral therapies currently available to control fatal outbreaks due in part to the lack of understanding of virus-mediated immunopathology. In our study, we used hemagglutinin (HA) of H5N1 virus to investigate the related signaling pathways and their relationship to dysregulated innate immune reaction. We found the HA of H5N1 avian influenza triggered an abnormal innate immune signalling in the pulmonary epithelial cells, through an unusual process involving activation of Janus kinase 3 (JAK3) that is exclusively associated with γc chain and is essential for signaling via all γc cytokine receptors. By using a selective JAK3 inhibitor and JAK3 knockout mice, we have, for the first time, demonstrated the ability to target active JAK3 to counteract injury to the lungs and protect immunocytes from acute hypercytokinemia -induced destruction following the challenge of H5N1 HA in vitro and in vivo. On the basis of the present data, it appears that the efficacy of selective JAK3 inhibition is likely based on its ability to block multiple cytokines and protect against a superinflammatory response to pathogen-associated molecular patterns (PAMPs) attack. Our findings highlight the potential value of selective JAK3 inhibitor in treating the fatal immunopathology caused by H5N1 challenge.

Evidence obtained from ANOVA to reason cross-species infection and cross-subtype mutation in neuraminidases of influenza A viruses

The current pandemic of A/H1N1 influenza raises a serious question on cross-species infection and cross-subtype mutation because our previous focus on possible influenza pandemic laid on H5N1 subtype and the cross-species infection between avian and human. In this study, we analyse 3874 neuraminidases from influenza A viruses using anova to answer the question of if there is barrier between species and between subtypes. The results show that there is no cross-species barrier in some species, and the intra-species variation is larger than the inter-species variation in some species hosting the viruses, and the cross-subtype mutation is possible because there is no cross-subtype barrier in some subtypes and the intra-subtype variation is larger than the inter-subtype variation in some subtypes. These results highlight the state of barrier of influenza A virus, which can help us understand the current pandemic and manufacture more effective vaccines.

Swine Influenza (H1N1) pneumonia: clinical considerations

Influenza is a viral zoonosis of birds and mammals that has probably existed since antiquity. Attack rates of influenza are relatively high but mortality is relatively low. Influenza mortality is highest in the very young, the very old, and the immunosuppressed. Influenza has the potential for rapid spread and may involve large populations. This article examines the swine influenza (H1N1) strain of recent origin, and compares the microbiology, epidemiology, clinical presentation, differential, clinical, and laboratory diagnosis, therapy, complications, and prognosis with previous recorded outbreaks of avian and human seasonal influenza pneumonias.

Influenza

Influenza is a highly contagious virus that causes an acute respiratory tract infection. Disease occurs in yearly outbreaks in humans, lasting 2–6 weeks in length. Influenza A and B predominate in these outbreaks, with more severe disease occurring with InfluenzaA. Additional infections with avian subtypes of influenza have also occurred in humans in the past decade, with notably increased morbidity and mortality. Vaccination is the mainstay for preventing disease. Antiviral drugs may be effective in decreasing duration and severity of disease, but evolving resistance has narrowed treatment options. This chapter provides a broad overview of influenza, from basic virology to epidemiology, disease, treatment, and prevention.

Taipei's use of a multi-channel mass risk communication program to rapidly reverse an epidemic of highly communicable disease

Background

In September 2007, an outbreak of acute hemorrhagic conjunctivitis (AHC) occurred in Keelung City and spread to Taipei City. In response to the epidemic, a new crisis management program was implemented and tested in Taipei.

Methodology and Principal Findings

Having noticed that transmission surged on weekends during the Keelung epidemic, Taipei City launched a multi-channel mass risk communications program that included short message service (SMS) messages sent directly to approximately 2.2 million Taipei residents on Friday, October 12th, 2007. The public was told to keep symptomatic students from schools and was provided guidelines for preventing the spread of the disease at home. Epidemiological characteristics of Taipei's outbreak were analyzed from 461 sampled AHC cases. Median time from exposure to onset of the disease was 1 day. This was significantly shorter for cases occurring in family clusters than in class clusters (mean±SD: 2.6±3.2 vs. 4.39±4.82 days, p = 0.03), as well as for cases occurring in larger family clusters as opposed to smaller ones (1.2±1.7 days vs. 3.9±4.0 days, p<0.01). Taipei's program had a significant impact on patient compliance. Home confinement of symptomatic children increased from 10% to 60% (p<0.05) and helped curb the spread of AHC. Taipei experienced a rapid decrease in AHC cases between the Friday of the SMS announcement and the following Monday, October 15, (0.70% vs. 0.36%). By October 26, AHC cases reduced to 0.01%. The success of this risk communication program in Taipei (as compared to Keelung) is further reflected through rapid improvements in three epidemic indicators: (1) significantly lower crude attack rates (1.95% vs. 14.92%, p<0.001), (2) a short epidemic period of AHC (13 vs. 34 days), and (3) a quick drop in risk level (1∼2 weeks) in Taipei districts that border Keelung (the original domestic epicenter).

Conclusions and Significance

The timely launch of this systematic, communication-based intervention proved effective at preventing a dangerous spike in AHC and was able to bring this high-risk disease under control. We recommend that public health officials incorporate similar methods into existing guidelines for preventing pandemic influenza and other emerging infectious diseases.

Respiratory infections unique to Asia

Asia is a highly heterogeneous region with vastly different cultures, social constitutions and populations affected by a wide spectrum of respiratory diseases caused by tropical pathogens. Asian patients with community‐acquired pneumonia differ from their Western counterparts in microbiological aetiology, in particular the prominence of Gram‐negative organisms, Mycobacterium tuberculosis, Burkholderia pseudomallei and Staphylococcus aureus. In addition, the differences in socioeconomic and health‐care infrastructures limit the usefulness of Western management guidelines for pneumonia in Asia. The importance of emerging infectious diseases such as severe acute respiratory syndrome and avian influenza infection remain as close concerns for practising respirologists in Asia. Specific infections such as melioidosis, dengue haemorrhagic fever, scrub typhus, leptospirosis, salmonellosis, penicilliosis marneffei, malaria, amoebiasis, paragonimiasis, strongyloidiasis, gnathostomiasis, trinchinellosis, schistosomiasis and echinococcosis occur commonly in Asia and manifest with a prominent respiratory component. Pulmonary eosinophilia, endemic in parts of Asia, could occur with a wide range of tropical infections. Tropical eosinophilia is believed to be a hyper‐sensitivity reaction to degenerating microfilariae trapped in the lungs.

This article attempts to address the key respiratory issues in these respiratory infections unique to Asia and highlight the important diagnostic and management issues faced by practising respirologists.

Guidelines on management of human infection with the novel virus influenza A (H1N1)--a report from the Hospital das Clínicas of the University of São Paulo

The pandemic novel influenza A (H1N1) infection was considered widespread in Brazil on July, 2009. Since then, 9.249 cases were confirmed in Brazil, most of them concentrated in São Paulo. The Hospital das Clínicas of the University of São Paulo is a reference center for H1N1 cases in São Paulo. The purpose of this review is to analyze the evidence concerning diagnosis, prevention, and treatment of novel influenza A (H1N1) infection. In addition, we propose guidelines for the management of this pandemic emphasizing Hospital das Clínicas "bundles" for the control of the pandemic novel influenza A (H1N1).

Role of hypercytokinemia in NF-kappaB p50-deficient mice after H5N1 influenza A virus infection

During H5N1 influenza virus infection, proinflammatory cytokines are markedly elevated in the lungs of infected hosts. The significance of this dysregulated cytokine response in H5N1-mediated pathogenesis remains to be determined. To investigate the influence of hypercytokinemia, or "cytokine storm," a transgenic mouse technology was used. The classical NF-kappaB pathway regulates the induction of most proinflammatory cytokines. Deletion of the p50 subunit leads to a markedly reduced expression of the NF-kappaB-regulated cytokines and chemokines. Here we show that H5N1 influenza virus infection of this transgenic mouse model resulted in a lack of hypercytokinemia but not in altered pathogenesis.

Risk for avian influenza virus exposure at human-wildlife interface

To assess risk for human exposure to avian influenza viruses (AIV), we sampled California wild birds and marine mammals during October 2005-August 2007 and estimated human-wildlife contact. Waterfowl hunters were 8 times more likely to have contact with AIV-infected wildlife than were persons with casual or occupational exposures (p<0.0001).

[Five years of the Robert Koch Institute guidelines for reprocessing of flexible endoscopes. A look back and a look forward]

In a short review the national and international reception of the German guidelines for reprocessing flexible endoscopes is presented. The recommendations of the guidelines are discussed in view of recent knowledge on old problems such as prion inactivation and new infectious diseases and new microorganisms such as SARS, avian influenza and C. difficile. New disinfectants and new methods for endoscope disinfection are mentioned, the importance of careful cleaning is underlined. The German guidelines of the Robert Koch Institute and the US Multi-Society guidelines, published in 2003, are compared. The discrepancies concerning recommendations for water quality for final rinsing and need of microbiological controls of endoscope reprocessing are stressed. Aspects not mentioned in the German guidelines, e.g. duration of storage after reprocessing and risk of infection transmission by the endo-washer, are discussed.