1,721,047 research outputs found
Avian Influenza virus serological study among poultry workers in Iran
No full textObjective: Since the mid-1990s, H9N2 subtype influenza A viruses have caused infections in the poultry population
around the globe, including several countries in Asia, Europe, North Africa and America. H9N2 influenza
viruses are currently circulating in the Middle and Far East, as well as in European poultry, and the infection
seems to be endemic in most developing countries.
A significant proportion of recent H9N2 isolates contains the L-226 mutation in their hemagglutinin (HA) receptor-
binding site and shows preferential binding to analogs of receptors with α2,6-linked sialic acid (SA), which
are traits typical of human viruses. Thus, these avian viruses might possess one of the key elements for infection
in humans. The H9N2 virus was isolated for the first time from humans in Hong Kong in 1999 and until now
different human cases of AI H9N2 have been reported in different countries. The wide circulation of H9N2 viruses
throughout Europe and Asia, along with their ability to cause direct infection in mammals and humans, raises
public health concerns about their potential to become candidates for the next influenza pandemic (Li KS et
al.2003) in addition to the H5N1 virus. Since 1998 H9N2 AI has been reported in Iran (Nili H. 2003) and at present
is endemic in the poultry industry; despite the control measures, which include mass vaccination of poultry,
this virus has spread rapidly and is currently circulating in the country (Vasfi Marandi M.2013). This study
was carried out to reveal the potential exposure to H9N2 AI viruses among Iranian poultry workers.
Methods: A total of 200 subjects took part in this study, including 100 poultry workers and 100 healthy residents.
Serum samples were collected and tested for the presence of antibodies against two different H9N2 avian
influenza viruses by haemagglutination inhibition (HI) and microneutralization (MN) assays, the analyses were
repeated at least three times. Two Iranian H9N2 strains were isolated in 1998 and 2008, which showed different
phylogenetic and important molecular differences at aa 226 (Q/L) (H3 numbering),
(A/chicken/Iran/12VIR/9630/1998)/Q, (A/chicken/Iran/10VIR/854-5/2008)/L. The viruses were replicated in SPF
chicken eggs and used in the serological study as antigens. In addition, all samples were tested for the presence
of seasonal H3N2, H1N1 2009 pandemic human influenza viruses to verify the presence of cross positivity
with the previously listed influenza viruses.
Results: Serological results showed that 16% of the exposed poultry workers were positive for the
A/chicken/Iran/10VIR/854-5/2008 virus in MN test and 12.33% in HI test using the titer > 40 as positive cut-off
value. Only 2% of the exposed staff was positive for the A/chicken/Iran/12VIR/9630/1998 virus. Seroprevalence
of control subjects for both H9N2 strains was very low in both tests (1-2%).
Conclusion: The results of this study have demonstrated that exposure to avian H9N2 viruses had occurred
among poultry workers in the Shiraz region – Iran, with a higher percentage than that recorded in the control
population of the same geographic area. Continuous surveillance programmes should be implemented to monitor
the presence of avian influenza infections in humans and to evaluate their potential threat to public health
and poultry workers
Comparative structural analysis of haemagglutinin proteins from type A influenza viruses: conserved and variable features.
Full text linkBackgroundGenome variation is very high in influenza A viruses. However, viral evolution and spreading is strongly influenced by immunogenic features and capacity to bind host cells, depending in turn on the two major capsidic proteins. Therefore, such viruses are classified based on haemagglutinin and neuraminidase types, e.g. H5N1. Current analyses of viral evolution are based on serological and primary sequence comparison; however, comparative structural analysis of capsidic proteins can provide functional insights on surface regions possibly crucial to antigenicity and cell binding.ResultsWe performed extensive structural comparison of influenza virus haemagglutinins and of their domains and subregions to investigate type- and/or domain-specific variation. We found that structural closeness and primary sequence similarity are not always tightly related; moreover, type-specific features could be inferred when comparing surface properties of haemagglutinin subregions, monomers and trimers, in terms of electrostatics and hydropathy. Focusing on H5N1, we found that variation at the receptor binding domain surface intriguingly relates to branching of still circulating clades from those ones that are no longer circulating.ConclusionsEvidence from this work suggests that integrating phylogenetic and serological analyses by extensive structural comparison can help in understanding the `functional evolution¿ of viral surface determinants. In particular, variation in electrostatic and hydropathy patches can provide molecular evolution markers: intriguing surface charge redistribution characterizing the haemagglutinin receptor binding domains from circulating H5N1 clades 2 and 7 might have contributed to antigenic escape hence to their evolutionary success and spreading
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Tick-borne encephalitis: rate of infection in the wood tick Ixodes ricinus in north-eastern Italy
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