H5N1 Avian Influenza Strain Research Articles

Expression of Avian Influenza Virus (H5N1) Hemagglutinin and Matrix Protein 1 in Pichia pastoris and Evaluation of their Immunogenicity in Mice

The conventional avian influenza vaccines rely on development of neutralizing antibodies against the HA and NA antigens. However, these antigens are highly variable, and hence there is a need for better vaccine candidates which would offer broader protection in animals. The M1 of avian influenza is another major structural protein that has conserved epitopes that are reported to induce CD8+ T cells and can contribute to protection against morbidity and mortality from influenza. Hence in an effort to study the immune response of rM1 either alone or in combination with rHA, the hemagglutinin (HA) and matrix protein (M1) of A/Hatay/2004/H5N1 strain of avian influenza were expressed in Pichia pastoris as his-tagged proteins and purified through Ni-NTA chromatography. The His-tag was removed using TEV protease cleavage site and the immunogenicity of purified rHA and rM1 either alone or in combination was determined in mice. One group of mice was immunized with 5μg of purified rHA, the other group was immunized with rM1, and a third group of mice were immunized with 5μg of rHA and rM1. All the animals were boosted twice, once on 28days postimmunization (dpi) and the second on 42dpi. The immune response was evaluated by enzyme-linked immunosorbent assay (ELISA) and hemagglutination inhibition (HI) assay. The group of mice immunized with rHA and rM1 together showed significantly higher immune response against rHA and rM1 than mice immunized with either HA or M1 antigens. The addition of rM1 with rHA resulted in increased HI titer in animals immunized with both the antigens. These results suggest that the HA and M1 expressed in P. pastoris can be utilized in combination for the development of faster and cost-effective vaccines for circulating and newer strains of avian influenza and would aid in combating the disease in a pandemic situation, in which production time matters greatly.

Anti-H5N1 virus flavonoids from Capparis sinaica Veill

Methanolic extract of Capparis sinaica Veill was tested for its in vitro antiviral activity against highly pathogenic avian influenza strain H5N1 using plaque inhibition assay in Madin–Darby canine kidney. The results indicated that the extract possessed potent antiviral activity (100% inhibition at the concentration of 1 μg/ml). Based on this result, C. sinaica Veill was selected for further study by applying bioactivity-guided fractionation to isolate its antiviral principles. The fractions eluted with EtOAc and 25% MeOH in EtOAc were found to hold the antiviral activity. Further chromatographic separation of the fractions holding the antiviral activity led to the isolation of quercetin (1), isoquercetin (2) and rutin (3) for the first time from this species. The isolates showed reduction in the virus titre by 68.13%, 79.66% and 73.22% inhibition at a concentration of 1 ng/ml, respectively.

Anti-H5N1 virus metabolites from the Red Sea soft coral, Sinularia candidula

Abstract A novel polyhydroxylated sterol, 3β-25-dihydroxy-4-methyl-5α,8α-epidioxy-2-ketoergost-9-ene ( 1 ) along with three new ceramides, N -[(2 S ,3 R , E )-1,3-dihydroxyhexacos-4-en-2-yl]icosanamide ( 2 ), N -[(2 S ,3 S ,4 R )-1,3,4-trihydroxyhexacosan-2-yl]icosanamide ( 3 ), and ( R )-2′-hydroxy- N -[(2 S ,3 S ,4 R )-1,3,4-trihydroxypentacosan-2-yl] nonadecanamide ( 4 ) were isolated from the Red Sea soft coral, Sinularia candidula. Complete structure elucidation was achieved through extensive spectroscopic analysis including one- and two-dimensional nuclear magnetic resonance spectroscopy. Sinularia candidula extracts of different polarities as well as the isolated pure compounds were screened against the highly pathogenic H5N1 avian influenza strain using the plaque inhibition assay in MDCK. The results indicated that the extracts of the Red Sea soft coral Sinularia candidula possessed potent antiviral activity (100% inhibition at a concentration of 1 μg/mL). The isolates 1 , 2 , 3 , and 4 showed reduction of virus titer by 55.16%, 48.81%, 10.43%, and 15.76% at a concentration of 1 ng/mL, respectively.

Anti-H5N1 virus new diglyceride ester from the Red Sea grass Thallasodendron ciliatum

Some Egyptian plants were screened against highly pathogenic avian influenza strain H5N1 using plaque inhibition assay in Madin–Darby canine kidney. The results indicated that the extracts of Red Sea grass Thallasodendron ciliatum possessed potent antiviral activity (100% inhibition at the concentration of 1 μg mL− 1). The bioactivity-guided fractionations led to the isolation of a new diglyceride ester (1) along with asebotin (2) for the first time from the plant. The two isolates showed reduction of virus titre by 67.26% and 53.81% inhibition at concentration of 1 ng mL− 1, respectively.

Inhibition of Autophagy Ameliorates Acute Lung Injury Caused by Avian Influenza A H5N1 Infection

The threat of a new influenza pandemic has existed since 1997, when the highly pathogenic H5N1 strain of avian influenza A virus infected humans in Hong Kong and spread across Asia, where it continued to infect poultry and people. The human mortality rate of H5N1 infection is about 60%, whereas that of seasonal H1N1 infection is less than 0.1%. The high mortality rate associated with H5N1 infection is predominantly a result of respiratory failure caused by acute lung injury; however, how viral infection contributes to this disease pathology is unclear. Here, we used electron microscopy to show the accumulation of autophagosomes in H5N1-infected lungs from a human cadaver and mice, as well as in infected A549 human epithelial lung cells. We also showed that H5N1, but not seasonal H1N1, induced autophagic cell death in alveolar epithelial cells through a pathway involving the kinase Akt, the tumor suppressor protein TSC2, and the mammalian target of rapamycin. Additionally, we suggest that the hemagglutinin protein of H5N1 may be responsible for stimulating autophagy. When applied prophylactically, reagents that blocked virus-induced autophagic signaling substantially increased the survival rate of mice and substantially ameliorated the acute lung injury and mortality caused by H5N1 infection. We conclude that the autophagic cell death of alveolar epithelial cells likely plays a crucial role in the high mortality rate of H5N1 infection, and we suggest that autophagy-blocking agents might be useful as prophylactics and therapeutics against infection of humans by the H5N1 virus.

Does Forewarned = Forearmed With Lab-Made Avian Influenza Strains?

The debate over whether journals should publish the full details of how two labs engineered the deadly avian influenza strain H5N1 so that it spreads more easily among ferrets, and presumably humans, shows that knowledge cuts both ways.

Continent-wide association of H5N1 outbreaks in wild and domestic birds in Europe

The highly pathogenic avian influenza strain H5N1 was first detected in Europe in 2005, and has since been documented continent-wide in wild birds and poultry. However, the relative roles of each host group in transmission remain contentious. Using recently developed tools for analysis of ecological niches and geographic distributions of species, we compared ecological niche requirements for H5N1 between paired host groups (poultry versus wild birds, Anseriformes versus Falconiformes, swans versus non-swan Anseriformes). If environmental signals of different host groups are significantly different, the groups are likely to be involved in distinct transmission cycles. In contrast, models for which similarity cannot be rejected imply no unique ecological niches and no potential linkage of transmission cycles. In 24 similarity tests, we found significant similarity (13/24) or no significant differences (9/24). Although 2 of the 24 analyses showed significant differences, neither was unequivocal, so we conclude an overall signal of niche similarity among groups. We thus could not document distinct ecological niches for H5N1 occurrences in different host groups and conclude that the transmission cycles are broadly interwoven.

Anticipatory‐Conjectural Policy Problems: A Case Study of the Avian Influenza

AbstractRarely, if ever, is the American policymaking process described as being a proactive one wherein policymakers strive to stave off or prepare for problems that have yet to have any substantive impact on a given population. Such problems, or “anticipatory‐conjectural policy problems,” are marked by acute uncertainty and thus demand a reconsideration of many of our fundamental assumptions about the nature of public policymaking. Using the H5N1 strain of avian influenza as a case study, the following work seeks to expand Thomas Birkland's concept of focusing events to encompass anticipatory‐conjectural policy problems. In addition, I will explore the unique agenda setting dynamics of these problems, paying particularly close attention to their definitional characteristics.

Long‐Distance Dispersal and Accelerating Waves of Disease: Empirical Relationships

Classic approaches to modeling biological invasions predict a "traveling wave" of constant velocity determined by the invading organism's reproductive capacity, generation time, and dispersal ability. Traveling wave models may not apply, however, for organisms that exhibit long-distance dispersal. Here we use simple empirical relationships for accelerating waves, based on inverse power law dispersal, and apply them to diseases caused by pathogens that are wind dispersed or vectored by birds: the within-season spread of a plant disease at spatial scales of <100 m in experimental plots, historical plant disease epidemics at the continental scale, the unexpectedly rapid spread of West Nile virus across North America, and the transcontinental spread of avian influenza strain H5N1 in Eurasia and Africa. In all cases, the position of the epidemic front advanced exponentially with time, and epidemic velocity increased linearly with distance; regression slopes varied over a relatively narrow range among data sets. Estimates of the inverse power law exponent for dispersal that would be required to attain the rates of disease spread observed in the field also varied relatively little (1.74-2.36), despite more than a fivefold range of spatial scale among the data sets.

A universal epitope-based influenza vaccine and its efficacy against H5N1

Previous studies have shown that a recombinant vaccine expressing four highly conserved influenza virus epitopes has a potential for a broad spectrum, cross-reactive vaccine; it induced protection against H1, H2 and H3 influenza strains. Here, we report on the evaluation of an epitope-based vaccine in which six conserved epitopes, common to many influenza virus strains are expressed within a recombinant flagellin that serves as both a carrier and adjuvant. In an HLA-A2.1 transgenic mice model, this vaccine induced both humoral and cellular responses and conferred some protection against lethal challenge with the highly pathogenic H5N1 avian influenza strain. Hence, it is expected to protect against future strains as well. The data presented, demonstrate the feasibility of using an array of peptides for vaccination, which might pave the way to an advantageous universal influenza virus vaccine that does not require frequent updates and/or annual immunizations.

Ecology and geography of avian influenza (HPAI H5N1) transmission in the Middle East and northeastern Africa

BackgroundThe emerging highly pathogenic avian influenza strain H5N1 ("HPAI-H5N1") has spread broadly in the past decade, and is now the focus of considerable concern. We tested the hypothesis that spatial distributions of HPAI-H5N1 cases are related consistently and predictably to coarse-scale environmental features in the Middle East and northeastern Africa.We used ecological niche models to relate virus occurrences to 8 km resolution digital data layers summarizing parameters of monthly surface reflectance and landform. Predictive challenges included a variety of spatial stratification schemes in which models were challenged to predict case distributions in broadly unsampled areas.ResultsIn almost all tests, HPAI-H5N1 cases were indeed occurring under predictable sets of environmental conditions, generally predicted absent from areas with low NDVI values and minimal seasonal variation, and present in areas with a broad range of and appreciable seasonal variation in NDVI values. Although we documented significant predictive ability of our models, even between our study region and West Africa, case occurrences in the Arabian Peninsula appear to follow a distinct environmental regime.ConclusionOverall, we documented a variable environmental "fingerprint" for areas suitable for HPAI-H5N1 transmission.

Reduced Serologic Response to Avian Influenza Vaccine in Specific-Pathogen-Free Chicks Inoculated with Cryptosporidium baileyi

Immunosuppression in chickens as a consequence of Cryptosporidium baileyi infection may compromise the effectiveness of vaccination for control of avian influenza (AI) H5N1. In a 13-wk study using 260 specific-pathogen-free chicks, immunological response and bursa weight:body weight ratios following vaccination against AI strain H5N1 were compared between uninfected and C baileyi-infected birds. The four experimental treatments were the following: infection with C. baileyi (5 x 10(5) oocysts dosed orally on day 0); C baileyi infection + vaccination against H5N1 (0.3 ml inactivated vaccine administered subcutaneously on day 7 and day 21; CB+VAC); vaccination only (VAC); and sham infection/vaccinations using sterile distilled water (control). At weekly intervals serum samples were analyzed by hemagglutination inhibition assay (HI), and five chicks/group were euthanatized for determination of bursa weights. In all but week 8, proportional bursa weights (bursa weight/body weight) were lower for CB+VAC chicks than for VAC chicks (i.e., the bursa index was below 1.0; average 0.81). Throughout the 13 wk, HI titres were lower (P < 0.01) in CB+VAC than in the VAC group, and compared with VAC, chicks in CB+VAC had a slightly shorter period of negative seroconversion. These data indicate bursal atrophy and immunosuppressive effects of C. baileyi infection on day-old chicks vaccinated against AI strain H5N1 and suggest that C. baileyi infection in chicks may increase the host susceptibility to AI virus.

Risk-based surveillance for h5n1 avian influenza virus in wild birds in Great Britain

Recent outbreaks of the h5n1 strain of avian influenza in Europe have highlighted the need for continuous surveillance and early detection to reduce the likelihood of a major outbreak in...

The US pandemic influenza implementation plan at six months

There has been great concern recently about pandemic influenza. The US government developed a National Strategy for Pandemic Influenza in November 2005, followed by an implementation plan in May 2006. A sixmonth progress report was published in late December. The current strategies are intended to improve preparedness and response for the next influenza pandemic. In comparison with the optimistic neglect that often characterized past planning for pandemic influenza, there has been considerable progress on a number of fronts in the past year. Despite this progress, major gaps remain. These include the coordination, encouragement and funding of international surveillance and cooperation; the need for new and more agile vaccine technologies; limitations in the use and distribution of antiviral agents; and communication with, and resources for, local responders and the public. One question is why, despite an estimated 36,000 seasonal influenza deaths annually in the United States alone, and a much greater number during pandemics, relatively little new basic research has been done for decades. This emphasizes both the need for and the difficulty of sustaining pandemic preparedness. There is good reason to be concerned about a future influenza pandemic. There were three in the twentieth century, in 1918–1919, 1957 and 1968, and most virologists believe that pandemics are inevitable1. The greatest influenza pandemic, in 1918–1919, was also the worst natural disaster in recorded history, with an estimate of over 50 million deaths worldwide2–4. Concern about the state of pandemic preparedness and response has been increasing over the last decade. In 1999, when the World Health Organization (WHO) produced pandemic planning recommendations, only Canada and the UK already had plans. By 2007, 29 countries had submitted plans (available at http://www.who.int/csr/disease/avian_ influenza/links/en/index.html) to WHO. Next year will mark the 90th anniversary of the great pandemic of 1918, making it especially timely to take stock of our readiness for the next pandemic. On 1 November 2005, the President of the United States declared that “nature has presented us with a daunting challenge: the possibility of an influenza pandemic,” and announced the government’s National Strategy for Pandemic Influenza (http://www. pandemicflu.gov, under Federal Planning). This strategy is intended to address the next influenza pandemic, whichever influenza virus is the cause. Although we do not know whether the H5N1 avian influenza strain will ever develop the ability to spread readily from person to person and thus become pandemic, this virus has recently been getting close scrutiny. It has already caused serious human illness and deaths, primarily although not exclusively through close contact with infected poultry. There have also been tremendous economic losses for poultry farmers.

Emergence of drug resistance: implications for antiviral control of pandemic influenza.

Given the danger of an unprecedented spread of the highly pathogenic avian influenza strain H5N1 in humans, and great challenges to the development of an effective influenza vaccine, antiviral drugs will probably play a pivotal role in combating a novel pandemic strain. A critical limitation to the use of these drugs is the evolution of highly transmissible drug-resistant viral mutants. Here, we develop a mathematical model to evaluate the potential impact of an antiviral treatment strategy on the emergence of drug resistance and containment of a pandemic. The results show that elimination of the wild-type strain depends crucially on both the early onset of treatment in indexed cases and population-level treatment. Given the probable delay of 0.5-1 day in seeking healthcare and therefore initiating therapy, the findings indicate that a single strategy of antiviral treatment will be unsuccessful at controlling the spread of disease if the reproduction number of the wild-type strain (R0s) exceeds 1.4. We demonstrate the possible occurrence of a self-sustaining epidemic of resistant strain, in terms of its transmission fitness relative to the wild-type, and the reproduction number R0s. Considering reproduction numbers estimated for the past three pandemics, the findings suggest that an uncontrollable pandemic is likely to occur if resistant viruses with relative transmission fitness above 0.4 emerge. While an antiviral strategy is crucial for containing a pandemic, its effectiveness depends critically on timely and strategic use of drugs.

SARS, avian flu, bioterror: infection control awareness for the optometrist

The outbreak of severe acute respiratory syndrome (SARS) in 2003 alerted the world to the new face of pandemic disease: highly contagious and fatal infections for which no vaccines are available and current drugs are largely ineffective. As a practitioner providing primary care, the optometrist must be familiar with new and evolving infections present in today’s society. Though they may be viewed as extreme events, scenarios such as the re‐emergence of SARS, the affliction posed by the H5N1 strain of avian influenza and the threat of a bioterrorist attack have all been described. In the event that such events occur, there is the potential for the spread of some highly virulent, transmissible disease.This paper highlights these public health threats and discusses several areas that the optometrist may want to consider regarding infection control in an era in which a highly transmissible disease is being spread from person to person.

A multi-scale problem arising in a model of avian flu virus in a seabird colony

Understanding the dynamics of epidemics of novel pathogens such as the H5N1 strain of avian influenza is of crucial importance to public and veterinary health as well as wildlife ecology. We model the effect of a new virus on a seabird colony, where no pre-existing Herd Immunity exists. The seabirds in question are so-called K-strategists, i.e. they have a relatively long life expectancy and very low reproductive output. They live in isolated colonies which typically contain tens of thousands of birds. These densely populated colonies, with so many birds competing for nesting space, would seem to provide perfect conditions for the entry and spread of an infection. Yet there are relatively few reported cases of epidemics among these seabirds. We develop a SEIR model which incorporates some of the unusual features of seabird population biology and examine the effects of introducing a pathogen into the colony.

Pandemic Vaccine Shows Promise

For the first time, a vaccine against the avian influenza strain H5N1 has shown promise at low doses, making it a possible candidate for use in a pandemic. In a statement issued last week, GlaxoSmithKline (GSK) said that a trial involving 400 healthy volunteers in Belgium revealed that two vaccine

Hybrid Viruses Fail to Spread

Scientists at the U.S. Centers for Disease Control and Prevention have created potential pandemic viruses that combine genes from a human influenza virus and the H5N1 avian influenza strain and report this week that the hybrid viruses are, at least in ferrets, relatively benign. (Read more.)

H5N1 Moves Into Africa, European Union, Deepening Global Crisis

European Union authorities called an urgent meeting after the H5N1 avian influenza strain was found in dead swans in Italy, Greece, Slovenia, and Austria, the first E.U. countries to be affected, and in Bulgaria. Even more disconcerting, H5N1 has gained a firm foothold on a third continent, Africa, where fighting it will be an uphill battle. (Read more.)