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Showing 7 results for Hemagglutinin
E Saberfar , A Najafi , H Lashini ,
Volume 1, Issue 4 (11-2007)
Abstract
Abstract : Avian influenza virus (AIV) infection is a major cause of influenza mortality in birds and can cause human mortality and morbidity. Although the risk of infection with avian influenza virus (AIV) is generally low for most people, the pathogenic virus can cross the species barrier and acquires the ability to infect and be transmitted among the human population; therefore the rapid identification of the virus is of important clinical and epidemiological implication. A reverse transcriptase-polymerase chain reaction (RT-PCR) was optimized for the detection of type A influenza virus. The assay differentiates avian H7 hemagglutinin subtypes. Two sets of specific oligonucleotide primers were used in this test for type A influenza virus and H7 heamagglutinin subtypes. The RT-PCR DNA products were visualized by gel electrophoresis and consisted of fragments of 98 bp for H7 hemagglutinin subtypes and 101 bp for type A influenza virus. The common set of primers for type A influenza virus were able to amplify a 101 bp DNA band for any of the other subtypes of influenza A virus. The RT-PCR assay developed in this study was found to be sensitive and specific. No specific amplification bands of the same sizes (98 bp) could be amplified for RNA of other influenza hemagglutinin subtypes, specific amplification bands of type A influenza (101 bp) for Influenza B, C, or other viral or bacterial pathogens was not tested in this study.
S Ghadi , Mh Bozorgmehri-Fard , V Karimi , M Tavassoti-Kheiri , Mh Rafiei ,
Volume 3, Issue 3 (10-2009)
Abstract
Background and Aims: Influenza A virus subtype H9N2 have continued to circulate in domestic poultry farms in Asia since 1998. The virus circulates in live bird markets, missing link in epidemiology of avian influenza. Regarding previous studies on H9N2 viruses of Iran and having no data on this subject in Iranian live bird markets this study was conducted to analyze genetically hemagglutinin protein of H9N1 virus. Methods: A total of 500 tracheal and cloacal swabs from clinically healthy birds of Tehran's live bird markets were collected. Diagnostic RT-PCR was done on them using specific primers for subtype H9N2. Eight positive samples were selected for inoculation into 9-11 days SPF emberyonated eggs and the virus was grown and isolated. Amplification of the HA gene was carried out by PCR using two pairs of specific primers. PCR products were separated, purified and cloned. The products were sequenced and analyzed with M13 primers. They shared high amino acid homology with genes of other H9N2 viruses isolated previously in Asia and Iran. Results: H9N2 viruses isolated from live bird markets were highly similar to viruses isolated from industrial poultry being circulated as early as 2001. Conclusion: The results suggest that a common source of H9N2 viruses is circulating in Iran.
R Tavakoli , F Fotouhi , M Tavassoti-Kheiri , B Farahmand , M Saleh , M Tabatabaeiyan ,
Volume 6, Issue 1 (2-2012)
Abstract
Background and Aims: Influenza (flu) is a respiratory infection in mammals and birds. It is caused by an RNA virus in the family Orthomyxoviridae. The virus is divided into three main types. Influenza virus type A is found in a wide variety of bird and mammal species and can undergo major shifts in immunological properties. Hemagglutinin (HA) is an important influenza virus surface antigen that is highly topical in influenza research. In the present study, the gene encoding HA1 protein which includes Hemagglutinin globular head from influenza virus A/Tehran/18/2010 (H1N1) was cloned into a eukaryotic expression plasmid (pCDNA3) and its expression was evaluated in eukaryotic cells. Materials and Methods: HA1 gene was incised from pFastBacTHc-HA1 by digestion, purified and subcloned into eukaryotic expression vector (pCDNA3). After verification of the cloning fidelity, the recombinant plasmid was transfected into COS-7 and BHK-21 cells, and its expression was detected by RT-PCR. Results: Restriction endonuclease digestion analysis, colony PCR and DNA sequencing indicated that the recombinant plasmid pCDNA3-HA1 had been constructed successfully. After transfection into eukaryotic cells, the presence of mRNA transcripts was verified by reverse transcriptase-polymerase chain reaction (RT-PCR). Conclusion: This study is a demonstrated success in the construction of eukaryotic expression plasmid for HA1 thus providing a basis for further probing into mechanism of virus infection and exploring DNA vaccine.
H Norouzian , Sj Gholami , M Vasfi-Marandi ,
Volume 6, Issue 1 (2-2012)
Abstract
Background and Aims: Hemagglutinin (HA) protein of Avian Influenza (AI) plays an essential role in the virus pathogenicity. AI H9N2 subtype causes significant economic loss in broiler and layer in poultry farms in Iran. AI viruses have a great involvement in evolutionary changes at nucleotide and amino acid levels and vaccines could induce faster rates of such changes. Up-dated understanding of the genetic changes of AI viruses circulating in Iran is necessary for controlling AI. Materials and Methods: Sequence analysis and phylogenetic study of the HA gene of three H9N2 subtype of AI isolates in Iran in 2010-2011 were studied. Results: Cleavage site of the Iranian 2010-2011 isolates possessed a different motif. Amino acid residue at position 226 at receptor binding site in these isolates was Leucine, which was similar to human viruses. The epitopes for HA showed a great variation related to the year of isolation. According to phylogenetic analysis, Iranian isolates were divided into two main subgroups. But, viruses isolated in this study formed a third minor subgroup. Degree of homology between the 2010-2011 isolates and former Iranian isolates was significantly low. Conclusion: The results revealed that HA of new Iranian AI H9N2 isolates have undergone extensive genetic changes. Definitely, continuous monitoring of genetic changes is a useful tool for updating control strategy for AI outbreak in Iran.
Moein Aliakbari, Farida Behzadian, Ali Asghar Deldar,
Volume 9, Issue 2 (5-2015)
Abstract
Abstract
Background and Aims: Influenza A(H5N1) viruses circulating in animals might evolve and acquire the ability to spread from human to human and thus start a pandemic. Hemagglutinin (HA) has been shown to play a major role in binding of influenza virus to its target cell and the main neutralizing antibody responses elicit against this region. Recent studies have shown that glycosylation of HA is not necessary for its immunogenicity. Bacillus subtilis has been identified as a free endotoxin host for high expression and secretion of heterologous proteins with immunological activity. This bacterium is not capable of supporting glycosylation process. However, it could be an appropriate host to produce new recombinant HA1 for vaccine research purposes. In this study we constructed a recombinant B. subtilis that was able to express and secrete HA1 protein into cytoplasmic and extracellular medium.
Materials and Methods: HA1 gene was amplified and cloned into pGEM® 5Zf(–) vector. It was then subcloned into shuttle vector PHT43 and transferred to E.coli for propagation. Accuracy of PHT43-HA1 construct was confirmed by sequencing and restriction map. The recombinant plasmid was extracted from E.coli and used to transform of B.subtilis by electroporation. Following IPTG induction, the total cell protein and the protein secreted into media were analysed through a time course using SDS-PAGE.
Results: The accuracy of PHT43-HA1 construct was confirmed by sequencing and enzymatic digestion analysis. SDS-PAGE results showed that the recombinant HA1 protein was successfully expressed and secreted into medium.
Conclusion: The HA1 protein produced here could be considered and evaluated as a protective antigen which its immunogenicity potential needs to be assessed in animal models along with proper control groups.
Saeideh Sadeghi Neshat, Behrokh Farahmand, Somayeh Zamani, Vahideh Mazaheri, Ali Torabi, Fatemeh Fotouhi,
Volume 11, Issue 3 (9-2017)
Abstract
Background and Aims: Influenza vaccine production process is time-consuming with little-to-no cross-protection which requires annual adjustment. The construction of a universal vaccine to deal with the pandemics and epidemics which occasionally threat human population is the aim of many researches worldwide. Today, influenza vaccines are mostly against two major antigenic proteins, hemagglutinin and neuraminidase. As compared to high variable globular head, the hemagglutinin stalk domain is more conserved among different subtypes of influenza A viruses which could be a good candidate to develop a cross-protective vaccine.
Materials and Methods: In this study, recombinant HA2 protein comprising fusion peptide was expressed in E.coli, purified using Ni-TED columns, refolded and desalted by dialysis. BALB/c mice in different groups were immunized with HA2 alone or supplemented with Alum or Alum/CPG. Vaccinated mice sera were examined for anti-HA2 specific IgG responses. Finally, mice were challenged with one LD90 of mouse-adapted A/PR8 virus.
Results: The results showed that HA2 recombinant protein could provoke immunogenicity in BALA/c mice and this immune response could be elevated with Alum and Alum/CpG. Despite promising immune responses, there was insignificant protection of HA2-immunized mice when challenged with the mouse-adapted strain A/PR8.
Conclusions: Therefore, HA2 protein alongside with other influenza virus conserved proteins should be studied to achieve a suitable vaccine formulation for broad spectrum cross-reactive immune responses.
Sakine Aboutalebi, Shahla Shahsavandi, Fahimeh Nemati, Nikdokht Ebrahimi,
Volume 14, Issue 1 (6-2020)
Abstract
Background and Aims: The emergence of drug-resistant influenza viruses has become a serious threat for human and animal populations. Glycyrrhiza glabra (Gg) is a traditional medicine clinically used for the treatment of viral respiratory infection symptoms in most countries. We evaluated the effects of the herb on influenza virus replication in human lung cultured cells (A549) following the determination of cytotoxic concentration 50 of Gg for the cell in culture.
Materials and Methods: Suspensions of influenza virus-infected A549 cells were examined for infectivity up to 48 h after the addition of Gg at various concentrations before and after adsorption of the virus. The possible anti-influenza activity of Gg was also determined using apoptosis detection.
Results: At concentrations ranging from 50 to 400 μg/ml, Gg did not cause a cytotoxic effect against the cells. The increase in viral titers before adsorption and a dose-dependent inhibitory action of Gg after virus adsorption indicated that the herb did not affect influenza virus replication in human epithelial respiratory cells. DNA fragmentation showed that Gg protected cells from influenza virus-induced apoptosis before and after adsorption of the virus.
Conclusion: The findings suggest that Gg cannot directly affect viral HA activity during virus replication. A decrease in virus titer after-treatment of the infected cells with higher concentrations of Gg may interact with cellular signaling factors either involved in viral entry or budding.
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