Malik Peiris

A highly conserved neutralizing epitope on group 2 influenza A viruses.

An antibody against a conserved epitope broadly neutralizes group 2 influenza viruses. Current flu vaccines provide only limited coverage against seasonal strains of influenza viruses. The identification of VH1-69 antibodies that broadly neutralize almost all influenza A group 1 viruses constituted a breakthrough in the influenza field. Here, we report the isolation and characterization of a human monoclonal antibody CR8020 with broad neutralizing activity against most group 2 viruses, including H3N2 and H7N7, which cause severe human infection. The crystal structure of Fab CR8020 with the 1968 pandemic H3 hemagglutinin (HA) reveals a highly conserved epitope in the HA stalk distinct from the epitope recognized by the VH1-69 group 1 antibodies. Thus, a cocktail of two antibodies may be sufficient to neutralize most influenza A subtypes and, hence, enable development of a universal flu vaccine and broad-spectrum antibody therapies.

Highly conserved protective epitopes on influenza B viruses.

Influenza Antibodies, Part B With its ability to reassort in animal hosts like pigs and birds, and to cause pandemics, influenza A viruses are often in the spotlight. However, a substantial portion of the annual flu burden is also the result of influenza B virus, which is a single influenza type that is characterized by two antigenically and genetically distinct lineages. Dreyfus et al. (p. 1343, published online 9 August) identify three monoclonal human antibodies that are able to protect against lethal infection with both lineages of influenza B virus in mice. Two antibodies, which bind to distinct regions of the viral hemagluttinin (HA) molecule, neutralize multiple strains from both lineages of influenza B virus, whereas the third antibody binds to the stem region of HA and is able to neutralize both influenza A and B strains. The structural data from these antibodies bound to HA, together with already known antibodies targeting influenza A, may provide clues for designing a universal vaccine to protect against both influenza virus types. Three broadly neutralizing human monoclonal antibodies protect mice against influenza B. Identification of broadly neutralizing antibodies against influenza A viruses has raised hopes for the development of monoclonal antibody–based immunotherapy and “universal” vaccines for influenza. However, a substantial part of the annual flu burden is caused by two cocirculating, antigenically distinct lineages of influenza B viruses. Here, we report human monoclonal antibodies, CR8033, CR8071, and CR9114, that protect mice against lethal challenge from both lineages. Antibodies CR8033 and CR8071 recognize distinct conserved epitopes in the head region of the influenza B hemagglutinin (HA), whereas CR9114 binds a conserved epitope in the HA stem and protects against lethal challenge with influenza A and B viruses. These antibodies may inform on development of monoclonal antibody–based treatments and a universal flu vaccine for all influenza A and B viruses.

Emergence and Dissemination of a Swine H3N2 Reassortant Influenza Virus with 2009 Pandemic H1N1 Genes in Pigs in China

ABSTRACT The 2009 pandemic influenza virus (pdm/09) has been frequently introduced to pigs and has reassorted with other swine viruses. Recently, H3N2 reassortants with pdm/09-like internal genes were isolated in Guangxi and Hong Kong, China. Genetic and epidemiological analyses suggest that these viruses have circulated in swine for some time. This is the first evidence that swine reassortant viruses with pdm/09-like genes may have become established in the field, altering the landscape of human and swine influenza.

Establishment and Lineage Replacement of H6 Influenza Viruses in Domestic Ducks in Southern China

ABSTRACT Domestic ducks in southern China act as an important reservoir for influenza viruses and have also facilitated the establishment of multiple H6 influenza virus lineages. To understand the continuing evolution of these established lineages, 297 H6 viruses isolated from domestic ducks during 2006 and 2007 were genetically and antigenically analyzed. Phylogenetic analyses showed that group II duck H6 viruses had replaced the previously predominant group I lineage and extended their geographic distribution from coastal to inland regions. Group II H6 virus showed that the genesis and development of multiple types of deletions in the neuraminidase (NA) stalk region could occur in the influenza viruses from domestic ducks. A gradual replacement of the N2 NA subtype with N6 was observed. Significant antigenic changes occurred within group II H6 viruses so that they became antigenically distinguishable from group I and gene pool viruses. Gene exchange between group II H6 viruses and the established H5N1, H9N2, or H6N1 virus lineages in poultry in the region was very limited. These findings suggest that domestic ducks can facilitate significant genetic and antigenic changes in viruses established in this host and highlight gaps in our knowledge of influenza virus ecology and even the evolutionary behavior of this virus family in its aquatic avian reservoirs.

Dual functions of ginsenosides in protecting human endothelial cells against influenza H9N2-induced inflammation and apoptosis.

ETHNOPHARMACOLOGICAL RELEVANCE Panax ginseng is a precious traditional Chinese herbal medicine which has been utilized as herbal tonic for improving immunity. The active component, ginsenosides have been shown to possess various pharmacological functions including immunomodulation and cardiovascular protection. AIM OF THE STUDY To investigate the immunomodulatory effect and anti-apoptotic effect of ginsenosides on avian influenza-infected human endothelial cells, and to present evidence for the cardiovascular protection by ginseng during influenza infection. MATERIALS AND METHODS Human umbilical vein endothelial cells (HUVECs) were infected with avian influenza H9N2/G1 to induce IP-10 production and cell death, cells were then incubated with ginsenosides PPT and Re. The level of IP-10 and microRNA was determined by ELISA and real-time PCR respectively. Cell death was determined by MTT, TUNEL and flow cytometry. RESULTS Ginsenoside metabolite protopanaxatriol showed significant suppression effect on IP-10 production upon H9N2/G1 infection through up-regulation of miR-15b expression. In addition, ginsenoside-induced cytoprotection was reflected in the increase of cell viability. Data from flow cytometry analysis and TUNEL assay also showed that ginsenoside Re could protect ECs from H9N2/G1-induced apoptosis and DNA damage. CONCLUSIONS This report further supports the traditional belief for immunomodulatory effects of ginseng, also demonstrated the partial protective mechanism of ginsenosides on avian influenza infection and its related endothelial dysfunction.

The Dynamic Relationship between Clinical Symptomatology and Viral Shedding in Naturally Acquired Seasonal and Pandemic Influenza Virus Infections

BACKGROUND Although the pattern of viral shedding over time has been documented in volunteer challenge studies, understanding of the relationship between clinical symptomatology and viral shedding in naturally acquired influenza infections in humans remains limited. METHODS In a community-based study in Hong Kong from 2008 to 2014, we followed up initially healthy individuals and identified 224 secondary cases of natural influenza virus infection in the household setting. We examined the dynamic relationship between patterns of clinical symptomatology and viral shedding as quantified using reverse transcription polymerase chain reaction and viral culture in 127 cases with a clinical picture of acute respiratory infection. RESULTS Viral shedding in influenza A virus infections peaked on the first 1-2 days of clinical illness, and decreased gradually to undetectable levels by day 6-7, matching closely with the dynamics of clinical illness. Viral shedding in influenza B virus infections rose up to 2 days prior to symptom onset and persisted for 6-7 days after onset with a bimodal pattern. CONCLUSIONS Our results suggest that while clinical illness profiles may serve as a proxy for clinical infectiousness in influenza A virus infections, patients may potentially be infectious even before symptom onset or after clinical improvement in influenza B virus infections.

Changing Patterns of H6 Influenza Viruses in Hong Kong Poultry Markets

Until 2001, H6N1 influenza viruses in the Hong Kong bird markets were represented by a single stable A/teal/Hong Kong/W312/97-like lineage. Beginning in 2001, despite a reduction in overall prevalence, an increase was observed in the number of H6 viruses isolated from chickens and other hosts. To assess any changes in H6 viruses, we characterized 18 H6 viruses isolated in the Hong Kong bird markets from 2001 to 2003. Experimental data showed that the 2003 H6 viruses had similar infectivity for chickens as did A/teal/HK/W312/97, and they were unable to transmit. Although all hemagglutinin genes were closely related to A/teal/HK/W312/97, 7 isolates were reassortant viruses containing similar gene segments of co-circulating H9N2 or H5N1 viruses. The receptor specificity was different from that of A/teal/Hong Kong/W312/97. Interestingly, similar observations have been documented in H9N2 viruses in Hong Kong. This evolution strongly suggests that some change in the ecology of influenza in the region selected for these changes. Taken together, these findings suggest that the H6 influenza viruses isolated in the Hong Kong markets are not well adapted to chickens and that the likely continued source of these viruses are other “minor” poultry species in which they are undergoing genetic and biologic evolution.

Pulmonary and central nervous system pathology in fatal cases of hand foot and mouth disease caused by enterovirus A71 infection

In the past 17 years, neurological disease associated with enterovirus A71 (EV-A71) has increased dramatically in the Asia-Pacific region with a high fatality rate in young infants, often due to pulmonary oedema, however the mechanism of this oedema remains obscure. We analysed the brainstem, heart and lungs of 15 fatal cases of confirmed EV-A71 infection in order to understand the pathophysiological mechanism of death and pulmonary oedema. In keeping with other case studies, the main cause of death was neurogenic pulmonary oedema. In the brainstem, 11 cases showed inflammation and all cases showed parenchymal inflammation with seven cases showing moderate or severe clasmatodendrosis. No viral antigen was detected in sections of the brainstem in any of the cases. All fatal cases showed evidence of pulmonary oedema; however, there was absence of direct pulmonary viral damage or myocarditis-induced damage and EV-A71 viral antigen staining was negative. Though there was no increase in staining for Na/K-ATPase, 11 of the 15 cases showed a marked reduction in aquaporin-4 staining in the lung, and this reduction may contribute to the development of fatal pulmonary oedema.

A59 Expansion of genetic diversity and interspecies transmission dynamics of swine influenza viruses in China

Lastly, we describe the nearly complete sequence of the Wuhan Tick Virus-like (WTV-like), which is comprised of one negativesense single stranded RNA molecule, with 11,208 nucleotides. This virus was classified into Chuviridae family and encodes the polymerase, glycoprotein, nucleoprotein, and VP4. Interestingly, the tick pools from all the four sites of collection were positive for MGTV, LT2V-like, and WTV-like viruses, indicating that these viruses can be found in the tick population of a large area of the Brazilian territory, which is an important cattle producing region in the country and one of the leading regions in animal produce exportation. On the other hand, only the MGTV was simultaneously detected in 19.4 per cent (7/36) serum cattle, indicating viremia in these animals. In summary, we have identified three potentially novel tick-borne viruses with broad distributions in South of Brazil, which include potential novel pathogens for cattle.

High throughput quantitative proteomic analysis of cellular host response to influenza virus in primary human monocyte-derived macrophages

Host response to infection with pathogens such as influenza viruses serves to primarily generate immune responses in an attempt to counter the invading pathogens. Consequently, how the host interacts with the virus not only has important influence on its pathogenesis, but also its transmission in a population and dissemination within the infected host. On the other hand, an overly active immune response may actually lead to excessive inflammation, which could be detrimental to the host as many lines of evidence have suggested for human H5N1 infection and the 1918 H1N1 pandemic virus. Macrophages are key orchestrator of the immune response and being one of the most abundant cell types in the respiratory system that can be infected with influenza viruses. Therefore, this study aims utilize high-throughput mass spectrometry to compare time series global proteomic profiles of primary human monocyte-derived macrophages infected with highly pathogenic H5N1 and seasonal H1N1 influenza viruses, in order to allow combinational analysis of proteomic datasets with existing body of transcriptomic datasets to provide further insight into the cellular and molecular host response to influenza virus infection. Global proteomic profiling of influenza virus infected macrophages revealed that many of the proteome changes could not be accounted for by transcriptomic profiling with microarrays. The low concordance of the global proteome profiling results with transcriptomic data indicates that high throughput quantitative proteomic analysis can provide a significant additional dimension to enable combinational analysis with existing datasets from studies using high-throughput genomic platforms. Results from this study suggest proteome changes in infected macrophages that were common to both viruses could be involved in processes that are similar, such as viral replication as both viruses replicate equally well in our macrophage model. On the other hand, pathways derived from analysis of differentially affected proteomes may contribute to the high pathogenic nature of H5N1 viruses. Therefore systematic integrative analysis of datasets from different sources could significantly contribute to detecting differentially expressed genes or pathways that are of relevance during virus infection and allows assessment of heterogeneity. This is likely to contribute to target identification for host-directed treatment of disease caused by influenza viruses.