Epidemiological and Virological Characteristics of Influenza Viruses Circulating in Cambodia from 2009 to 2011

Background

The Cambodian National Influenza Center (NIC) monitored and characterized circulating influenza strains from 2009 to 2011.

Methodology/Principal Findings

Sentinel and study sites collected nasopharyngeal specimens for diagnostic detection, virus isolation, antigenic characterization, sequencing and antiviral susceptibility analysis from patients who fulfilled case definitions for influenza-like illness, acute lower respiratory infections and event-based surveillance. Each year in Cambodia, influenza viruses were detected mainly from June to November, during the rainy season. Antigenic analysis show that A/H1N1pdm09 isolates belonged to the A/California/7/2009-like group. Circulating A/H3N2 strains were A/Brisbane/10/2007-like in 2009 before drifting to A/Perth/16/2009-like in 2010 and 2011. The Cambodian influenza B isolates from 2009 to 2011 all belonged to the B/Victoria lineage represented by the vaccine strains B/Brisbane/60/2008 and B/Malaysia/2506/2004. Sequences of the M2 gene obtained from representative 2009–2011 A/H3N2 and A/H1N1pdm09 strains all contained the S31N mutation associated with adamantanes resistance except for one A/H1N1pdm09 strain isolated in 2011 that lacked this mutation. No reduction in the susceptibility to neuraminidase inhibitors was observed among the influenza viruses circulating from 2009 to 2011. Phylogenetic analysis revealed that A/H3N2 strains clustered each year to a distinct group while most A/H1N1pdm09 isolates belonged to the S203T clade.

Conclusions/Significance

In Cambodia, from 2009 to 2011, influenza activity occurred throughout the year with peak seasonality during the rainy season from June to November. Seasonal influenza epidemics were due to multiple genetically distinct viruses, even though all of the isolates were antigenically similar to the reference vaccine strains. The drug susceptibility profile of Cambodian influenza strains revealed that neuraminidase inhibitors would be the drug of choice for influenza treatment and chemoprophylaxis in Cambodia, as adamantanes are no longer expected to be effective.     

Synthesis and characterization of a triphenylphosphonium-conjugated peroxidase mimetic. Insights into the interaction of ebselen with mitochondria

Mitochondrial production of peroxides is a critical event in both pathology and redox signaling. Consequently their selective degradation within mitochondria is of considerable interest. Here we have explored the interaction of the peroxidase mimetic ebselen with mitochondria. We were particularly interested in whether ebselen was activated by mitochondrial glutathione (GSH) and thioredoxin, in determining whether an ebselen moiety could be targeted to mitochondria by conjugating it to a lipophilic cation, and in exploring the nature of ebselen binding to mitochondrial proteins. To achieve these goals we synthesized 2-[4-(4-triphenylphosphoniobutoxy) phenyl]-1,2-benzisoselenazol)-3(2H)-one iodide (MitoPeroxidase), which contains an ebselen moiety covalently linked to a triphenylphosphonium (TPP) cation. The fixed positive charge of TPP facilitated mass spectrometric analysis, which showed that the ebselen moiety was reduced by GSH to the selenol form and that subsequent reaction with a peroxide reformed the ebselen moiety. MitoPeroxidase and ebselen were effective antioxidants that degraded phospholipid hydroperoxides, prevented lipid peroxidation, and protected mitochondria from oxidative damage. Both peroxidase mimetics required activation by mitochondrial GSH or thioredoxin to be effective antioxidants. Surprisingly, conjugation to the TPP cation led to only a slight increase in the uptake of ebselen by mitochondria due to covalent binding of the ebselen moiety to proteins. Using antiserum against the TPP moiety we visualized those proteins covalently attached to the ebselen moiety. This analysis indicated that much of the ebselen present within mitochondria is bound to protein thiols through reversible selenenylsulfide bonds. Both MitoPeroxidase and ebselen decreased apoptosis induced by oxidative stress, suggesting that they can decrease mitochondrial oxidative stress. This exploration has led to new insights into the behavior of peroxidase mimetics within mitochondria and to their use in investigating mitochondrial oxidative damage.     

Lipophilic triphenylphosphonium cations as tools in mitochondrial bioenergetics and free radical biology

Lipophilic phosphonium cations were first used to investigate mitochondrial biology by Vladimir Skulachev and colleagues in the late 1960s. Since then, these molecules have become important tools for exploring mitochondrial bioenergetics and free radical biology. Here we review why these molecules are useful in mitochondrial research and outline some of the ways in which they are now being utilized.Translated from Biokhimiya, Vol. 70, No. 2, 2005, pp. 273–283.Original Russian Text Copyright ¢ 2005 by Ross, Kelso, Blaikie, James, Cochemé, Filipovska, Da Ros, Hurd, Smith, Murphy.This revised version was published online in April 2005 with corrections to the post codes.     

Ferredoxin reductase affects p53-dependent, 5-fluorouracil-induced apoptosis in colorectal cancer cells

Loss of p53 gene function, which occurs in most colon cancer cells, has been shown to abolish the apoptotic response to 5-fluorouracil (5-FU). To identify genes downstream of p53 that might mediate these effects, we assessed global patterns of gene expression following 5-FU treatment of isogenic cells differing only in their p53 status. The gene encoding mitochondrial ferredoxin reductase (protein, FR; gene, FDXR) was one of the few genes significantly induced by p53 after 5-FU treatment. The FR protein was localized to mitochondria and suppressed the growth of colon cancer cells when over-expressed. Targeted disruption of the FDXR gene in human colon cancer cells showed that it was essential for viability, and partial disruption of the gene resulted in decreased sensitivity to 5-FU-induced apoptosis. These data, coupled with the effects of pharmacologic inhibitors of reactive oxygen species, indicate that FR contributes to p53-mediated apoptosis through the generation of oxidative stress in mitochondria.     

Clonal heterogeneity in colony stimulating factor production by murine T lymphocytes

A panel of 55 alloreactive murine T-lymphocyte clones was screened for the production of granulocyte-macrophage colony stimulating factor (GM-CSF), multilineage CSF (multi-CSF), human-active eosinophil CSF (human-active EO-CSF), and interleukin 2 (IL-2) in response to stimulation with the lectin concanavalin A. Many clones were also characterized for cytolytic specificity and expression of the T-cell antigen receptor-associated surface markers Lyt-2 and L3T4, which reflect their specificity for Class I (H-2K, H-2D) or Class II (H-2l, Mls) histocompatibility antigens, respectively. Eighty percent of the clones secreted detectable quantities of at least one of the four factors measured. Of the factor-producing clones, all appeared to secrete GM-CSF and half also secreted multi-CSF. A subpopulation of multi-CSF producers also released human-active EO-CSF. More than half of the factor-producing clones secreted detectable IL-2; whereas the IL-2-producing clones included some that did not secrete multi-CSF, IL-2 production was always associated with concomitant synthesis of GM-CSF. Comparison of the range and quantities of factors secreted by Lyt-2+ and L3T4+ clones indicated that more L3T4+ clones produced measurable titers of the four factors; on average, this group also secreted 10- to 100-fold higher titers of both the hemopoietic regulators and IL-2 than Lyt-2+ clones. Cells of the L3T4+ phenotype would therefore be expected to account for the majority of CSF and IL-2 secretion by polyclonal populations of activated T lymphocytes.     

Cost-effective strategies for mitigating a future influenza pandemic with H1N1 2009 characteristics

Background

We performed an analysis of the cost-effectiveness of pandemic intervention strategies using a detailed, individual-based simulation model of a community in Australia together with health outcome data of infected individuals gathered during 2009–2010. The aim was to examine the cost-effectiveness of a range of interventions to determine the most cost-effective strategies suitable for a future pandemic with H1N1 2009 characteristics.

Methodology/Principal Findings

Using transmissibility, age-stratified attack rates and health outcomes determined from H1N1 2009 data, we determined that the most cost-effective strategies involved treatment and household prophylaxis using antiviral drugs combined with limited duration school closure, with costs ranging from $632 to $777 per case prevented. When school closure was used as a sole intervention we found the use of limited duration school closure to be significantly more cost-effective compared to continuous school closure, a result with applicability to countries with limited access to antiviral drugs. Other social distancing strategies, such as reduced workplace attendance, were found to be costly due to productivity losses.

Conclusion

The mild severity (low hospitalisation and case fatality rates) and low transmissibility of H1N1 2009 meant that health treatment costs were dominated by the higher productivity losses arising from workplace absence due to illness and childcare requirements following school closure. Further analysis for higher transmissibility but with the same, mild severity had no effect on the overall findings.     

The Cost Effectiveness of Pandemic Influenza Interventions: A Pandemic Severity Based Analysis

Background

The impact of a newly emerged influenza pandemic will depend on its transmissibility and severity. Understanding how these pandemic features impact on the effectiveness and cost effectiveness of alternative intervention strategies is important for pandemic planning.

Methods

A cost effectiveness analysis of a comprehensive range of social distancing and antiviral drug strategies intended to mitigate a future pandemic was conducted using a simulation model of a community of ∼30,000 in Australia. Six pandemic severity categories were defined based on case fatality ratio (CFR), using data from the 2009/2010 pandemic to relate hospitalisation rates to CFR.

Results

Intervention strategies combining school closure with antiviral treatment and prophylaxis are the most cost effective strategies in terms of cost per life year saved (LYS) for all severity categories. The cost component in the cost per LYS ratio varies depending on pandemic severity: for a severe pandemic (CFR of 2.5%) the cost is ∼$9 k per LYS; for a low severity pandemic (CFR of 0.1%) this strategy costs ∼$58 k per LYS; for a pandemic with very low severity similar to the 2009 pandemic (CFR of 0.03%) the cost is ∼$155 per LYS. With high severity pandemics (CFR >0.75%) the most effective attack rate reduction strategies are also the most cost effective. During low severity pandemics costs are dominated by productivity losses due to illness and social distancing interventions, while for high severity pandemics costs are dominated by hospitalisation costs and productivity losses due to death.

Conclusions

The most cost effective strategies for mitigating an influenza pandemic involve combining sustained social distancing with the use of antiviral agents. For low severity pandemics the most cost effective strategies involve antiviral treatment, prophylaxis and short durations of school closure; while these are cost effective they are less effective than other strategies in reducing the infection rate.     

Genetic diversity and gene flow within and between two different habitats of Primula merrilliana (Primulaceae), an endangered distylous forest herb in eastern China

Understanding whether and how different habitats shape population genetics is a fundamental question and a specific goal for evolutionary and conservation biology research. This study examined genetic diversity and gene flow within and between mountain and foothill habitats of Primula merrilliana, an endangered distylous forest herb in eastern China. Eleven population characteristics, including area, size and density variation, from the two habitats were also investigated. Mountain populations had significantly higher mean genetic diversity than foothill populations, which may be explained by stronger self‐incompatibility breeding system, more opportunity to use elevational shifts to track suitable sites under conditions of climate change and more heterogeneous environments in the former habitat, rather than by the differences of population size, gene flow and genetic drift intensity between them. Genetic analysis revealed that two distinct lineages, corresponding to the two habitats, diverged at China's ‘Last Glaciation’ (11 700–67 500 yr BP), suggesting this divergence was probably triggered by warmer climates during inter‐ (or post‐) glacial periods. Low unidirectional gene flow from mountain to foothill habitats, chiefly by seed dispersal, played a more important role in overall gene flow between habitats than within‐habitat gene flow. Within habitats, pollen contributes more substantially to gene flow than seed dispersal, especially in foothill habitats, possibly due to higher individual density and larger population sizes. These results have implications for the conservation in this and similar landscape areas and indicate the need to protect suitable habitats with wide elevational spans and sufficient size to permit ecological and elevational shifts in response to climatic changes. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 172–189.     

Mitochondrially targeted antioxidants and thiol reagents

Mitochondrial oxidative damage and dysfunction contributes to a number of cell pathologies. To investigate how this damage affects cell function we have developed mitochondrially targeted antioxidants and thiol reagents by covalently linking them to lipophilic cations. The cation drives the selective accumulation of these reagents into mitochondria within cells where the antioxidants decrease oxidative damage and the thiol reagents enable measurement of the redox status of thiol proteins. In conjunction with cell and animal models of apoptosis, oxidative damage, and nitric oxide signaling, these molecules may provide new insights into the roles of mitochondria in human pathologies.