The induction of virus-neutralizing antibodies in influenza A-infected mice treated with Oseltamivir phosphate: effect of dosage and scheduling.

Oseltamivir phosphate (OS) is currently the most frequently used influenza antiviral drug. It moderates the course of influenza virus type A (IAV) infection, however, its impact on the induction of virus-neutralizing antibodies (VNAbs) is not understood in details. Here, we examined the influence of low (10 mg/kg) or high (60 mg/kg) doses of OS on the viral titer in lungs of BALB/c mice infected with 0.

The Contribution of Viral Proteins to the Synergy of Influenza and Bacterial Co-Infection.

A severe course of acute respiratory disease caused by influenza A virus (IAV) infection is often linked with subsequent bacterial superinfection, which is difficult to cure. Thus, synergistic influenza-bacterial co-infection represents a serious medical problem. The pathogenic changes in the infected host are accelerated as a consequence of IAV infection, reflecting its impact on the host immune response.

Quantification of bacteria by in vivo bioluminescence imaging in comparison with standard spread plate method and reverse transcription quantitative PCR (RT-qPCR).

In vivo bioluminescence imaging (BLI) offers a unique opportunity to analyze ongoing bacterial infections qualitatively and quantitatively in intact animals over time, leading to a reduction in the number of animals needed for a study. Since accurate determination of the bacterial burden plays an essential role in microbiological research, the present study aimed to evaluate the ability to quantify bacteria by non-invasive BLI technique in comparison to standard spread plate method and reverse transcription quantitative PCR (RT-qPCR). For this purpose, BALB/c mice were intranasally infected with 1 × 10 CFU of bioluminescent Streptococcus pneumoniae A66.

DNA vaccine targeting the ectodomain of influenza M2 protein to endolysosome pathway enhances anti-M2e protective antibody response in mice.

A promising candidate for developing the universal influenza vaccine is the ectodomain of the M2 protein (M2e). We designed and prepared an experimental DNA vaccine with an improved potential to induce anti-M2e immune response. The sequence for truncated NS1 protein followed by 4xM2e was inserted into the expression vector pTriEx-4 (pEx).

Universal anti-influenza vaccines based on viral HA2 and M2e antigens.

Aquatic birds are the main reservoir of influenza A viruses (IAVs). These viruses can infect humans repeatedly and cause acute respiratory disease with potential of spread in the form of epidemics. In addition, avian influenza viruses that overcome the interspecies barrier and adapt to humans can cause a world-wide pandemic with severe consequences to human health.

Different mechanisms of the protection against influenza A infection mediated by broadly reactive HA2-specific antibodies.

Influenza A viruses (IAVs) cause yearly repeating infections in humans. The current vaccination approach is based on the production of virus-neutralizing antibodies. Virus-neutralizing antibodies, however, are closely strain-specific due to the IAV variability.

Biological properties of influenza A virus mutants with amino acid substitutions in the HA2 glycoprotein of the HA1/HA2 interaction region.

Influenza A viruses (IAVs) enter into cells by receptor-dependent endocytosis. Subsequently, conformational changes of haemagglutinin are triggered by low environmental pH and the N terminus of HA2 glycoprotein (gp) is inserted into the endosomal membrane, resulting in fusion pore formation and genomic vRNA release into the cytoplasm. However, the pH optimum of membrane fusion is host- and virus-specific and can have an impact on virus pathogenicity.

Avian influenza A virus adaptation to the equine host and identification of host-specific markers.

Avian influenza A viruses (IAVs) are able to overcome the interspecies barrier and adapt to the new non-avian host. The process of adaptation requires the adaptive changes of IAV genome resulting in amino acid substitutions. The aim of this work was the description of amino acid substitutions in avian influenza A viruses (IAVs) occurring during their adaptation to equine host.

Comparison of infectious influenza A virus quantification methods employing immuno-staining.

Infections caused by highly variable influenza A viruses (IAVs) pose perpetual threat to humans as well as to animals. Their surveillance requires reliable methods for their qualitative and quantitative analysis. The most frequently utilized quantification method is the titration by plaque assay or 50% tissue culture infectious dose estimation by TCID.

Stereoisomers of oseltamivir - synthesis, in silico prediction and biological evaluation.

Oseltamivir is an important antiviral drug, which possess three chirality centers in its structure. From eight possible stereoisomers, only two have been synthesized and evaluated so far. We describe herein the stereoselective synthesis, computational activity prediction and biological testing of another three diastereoisomers of oseltamivir.

The influence of dual infection with herpes and influenza viruses on the differential blood cell count of mice.

Based on our previous results, which confirmed the role of latent gammaherpesvirus infection in alteration of immune homeostasis, we studied the influence of simultaneous infection with gammaherpes and influenza viruses on selected parameters of innate immunity, particularly on the subpopulations of peripheral blood cell leukocytes. The aim was to analyze changes of differential blood cell count of BALB/c mice persistently infected with murine gammaherpesvirus 68 (MHV-68) and subsequently co-infected with influenza A virus (IAV), in comparison to mice infected with MHV-68 or with IAV only. Our results showed that ongoing gammaherpesvirus latency in mice caused a decreased number of leukocytes after acute infection with IAV in comparison to a single acute IAV infection.

The role of fusion activity of influenza A viruses in their biological properties.

Influenza A viruses (IAVs) cause acute respiratory infections of humans, which are repeated yearly. Human IAV infections are associated with significant morbidity and mortality and therefore they represent a serious health problem. All human IAV strains are originally derived from avian IAVs, which, after their adaptation to humans, can spread in the human population and cause pandemics with more or less severe course of the disease.

Simultaneous infection with gammaherpes and influenza viruses enhances the host immune defense.

We have studied the impact of simultaneous infection of mice with murine gammaherpesvirus (MHV) and influenza A virus (IAV) on the immune response and pathogenesis of both infections. After a persistent MHV-68 herpesviral infection had been established, the same mice were super-infected with IAV. Individual parameters of MHV infection (viral DNA detection in organs and blood) and numbers of leukocytes in lungs and spleens were determined.

Immune response of mice to non-adapted avian influenza A virus.

Human infections with avian influenza A viruses (IAVs) without or with clinical symptoms of disease were recently reported from several continents, mainly in high risk groups of people, who came into the contact with infected domestic birds or poultry. It was shown that avian IAVs are able to infect humans directly without previous adaptation, however, their ability to replicate and to cause a disease in this new host can differ. No spread of these avian IAVs among humans has been documented until now, except for one case described in Netherlands in the February of 2003 in people directly involved in handling IAV (H7N7)-infected poultry.

Perspective of Use of Antiviral Peptides against Influenza Virus.

The threat of a worldwide influenza pandemic has greatly increased over the past decade with the emergence of highly virulent avian influenza strains. The increased frequency of drug-resistant influenza strains against currently available antiviral drugs requires urgent development of new strategies for antiviral therapy, too. The research in the field of therapeutic peptides began to develop extensively in the second half of the 20(th) century.

Virus-neutralizing antibody response of mice to consecutive infection with human and avian influenza A viruses.

In this work we simulated in a mouse model a naturally occurring situation of humans, who overcame an infection with epidemic strains of influenza A, and were subsequently exposed to avian influenza A viruses (IAV). The antibody response to avian IAV in mice previously infected with human IAV was analyzed. We used two avian IAV (A/Duck/Czechoslovakia/1956 (H4N6) and the attenuated virus rA/Viet Nam/1203-2004 (H5N1)) as well as two human IAV isolates (virus A/Mississippi/1/1985 (H3N2) of medium virulence and A/Puerto Rico/8/1934 (H1N1) of high virulence).

The ubiquitination of the influenza A virus PB1-F2 protein is crucial for its biological function.

The aim of the present study was to identify what influences the short half-life of the influenza A virus PB1-F2 protein and whether a prolonged half-life affects the properties of this molecule. We hypothesized that the short half-life of PB1-F2 could conceal the phenotype of the protein. Because proteasome degradation might be involved in PB1-F2 degradation, we focused on ubiquitination, a common label for proteasome targeting.

HA2 glycopolypeptide of influenza A virus and antiviral immunity.

Influenza A viruses (IAVs) cause acute respiratory infections in humans against which an effective prevention has not yet been developed due to their high variability and broad host specificity. The permanent threat of arising new influenza pandemic is represented by avian viruses which after their interspecies transmission can cause a disease with a devastating impact on humans lacking the specific immunity. Since the current vaccines inducing virus-neutralizing (VN) antibodies are targeted at a variable globular part of hemagglutinin (HA), their efficacy is limited and they need permanent updating.

Two distinct regions of HA2 glycopolypeptide of influenza virus hemagglutinin elicit cross-protective immunity against influenza.

Unlabelled: Currently, a new trend in development of vaccines against influenza with broader spectrum of efficacy is focused on conserved antigens of influenza virus. The HA2 glycopolypeptide (HA2 gp) is one of conserved antigens, potentially suitable as immunogens inducing cross-protection against influenza. We selected two distinct domains of HA2 gp originating from influenza A virus (IAV) of H3 subtype for induction of antiviral immune response: the ectodomain (EHA2) comprising aa 23-185 and the fusion peptide (FP) comprising N-terminal aa 1-38.

Heterosubtypic protection against influenza A induced by adenylate cyclase toxoids delivering conserved HA2 subunit of hemagglutinin.

The protective efficacy of currently available influenza vaccines is restricted to vaccine strains and their close antigenic variants. A new strategy to obtain cross-protection against influenza is based on conserved antigens of influenza A viruses (IAV), which are able to elicit a protective immune response. Here we describe a vaccination approach involving the conserved stem part of hemagglutinin, the HA2 subunit, shared by different HA subtypes of IAV.

Epitope specificity of anti-HA2 antibodies induced in humans during influenza infection.

Background: The conserved, fusion-active HA2 glycopolypeptide (HA2) subunit of influenza A hemagglutinin comprises four distinct antigenic sites. Monoclonal antibodies (MAbs) recognizing three of these sites are broadly cross-reactive and protective.

Objectives: This study aimed to establish whether antibodies specific to these three antigenic sites were elicited during a natural influenza infection or by vaccination of humans.

Evaluation of anti-influenza efficiency of polyclonal IgG antibodies specific to the ectodomain of M2 protein of influenza A virus by passive immunization of mice.

We attempted to quantify the protective potential of polyclonal IgG antibodies specific to the ectodomain of M2 protein (eM2) of influenza A virus (IAV) against lethal influenza infection of mice. For this purpose, eM2 conjugated with keyhole limpet hemocyanin (KLH) or KLH alone were administered with Freund's adjuvant intraperitoneally (i.p.

Heterosubtypic protective immunity against influenza A virus induced by fusion peptide of the hemagglutinin in comparison to ectodomain of M2 protein.

Several types of influenza vaccines are available, but due to the highly unpredictable variability of influenza virus surface antigens (hemagglutinin (HA) and neuraminidase) current vaccines are not sufficiently effective against broad spectrum of the influenza viruses. An innovative approach to extend the vaccine efficacy is based on the selection of conserved influenza proteins with a potential to induce inter-subtype protection against the influenza A viruses. A promising new candidate for the preparation of broadly protective vaccine may be a highly conserved N-terminal part of HA2 glycopolypeptide (HA2 gp) called fusion peptide.

Conserved epitopes of influenza A virus inducing protective immunity and their prospects for universal vaccine development.

Influenza A viruses belong to the best studied viruses, however no effective prevention against influenza infection has been developed. The emerging of still new escape variants of influenza A viruses causing epidemics and periodic worldwide pandemics represents a threat for human population. Therefore, current, hot task of influenza virus research is to look for a way how to get us closer to a universal vaccine.