Genomic study of hemagglutinins of swine influenza (H1N1) viruses associated with acute and chronic respiratory diseases in pigs

Abstract

The nucleotide sequences of HA1 domain of hemagglutinin of clinical H1N1 influenza viruses, isolated during recent outbreaks of respiratory problems in pig farms of Quebec, was determined. The viruses A/Sw/Quebec/3291/90 (SwQc3291) and A/Sw/Quebec/1747/90 (SwQc1747), associated with chronic respiratory disease, showed close similarity for their deduced aa sequences. When compared with the published data of A/Sw/Quebec/5393/91 (SwQc91), the variations observed included Cb and Ca antigenic sites in SwQc3291 and Sb and Ca sites in SwQc1747 isolates. These variants were antigenically related to SwQc91 virus associated with chronic respiratory disease, but differed from the more classical A/Sw/Quebec/192/81 (SwQc81) strain. In contrast, A/Sw/Quebec/1192/86 (SwQc1192) isolate, associated with acute respiratory influenza, showed maximum number of differences including Ca, Cb, Sa and Sb antigenic sites. The latter, as well as the SwQc81 strain, were antigenically distinct from SwQc91 virus on the basis of its cross-reactivity to MAbs directed against the HA glycoprotein. Estimation of genetic distances and phylogenic tree analysis showed that SwQc1747 and SwQc3291 were closely related, but these viruses along with SwQc1192 were considerably divergent from SwQc91 virus.

Emerging Antigenic Variants at the Antigenic Site Sb in Pandemic A(H1N1)2009 Influenza Virus in Japan Detected by a Human Monoclonal Antibody

“…The emergence of Sb antigenic variants was revealed using HuMAb 5E4. By contrast, it is not clear whether the emergence of the genetic variants in Ca2 was caused by selective pressure on Ca2 itself or by structural compensation for the mutations in Sb [46,47]. Four or more amino acid changes occurring in at least two of the five antigenic sites of HA are generally seen in significant antigenic variants [48,49].…”

New Outbreak of Swine Influenza in the Czech Republic

“…In Europe, including the Czech Republic, it was prevailing in the 1950s and 1960s, with the exception of Great Britain where it remained predominant till 1990s, and was subsequently replaced by an avian variant of the H1N1 subtype transmitted from wild birds (Arora et al 1997). This variant infected our pig population probably about 1979 and, in the following years, it was responsible for a series of epidemics on the Continent and gradually became established instead of the original H1N1 subtype.…”

A Systematic Review Analyzing the Prevalence and Circulation of Influenza Viruses in Swine Population Worldwide

“…The histopathology confirmed the bronchitis in the deceased swine and a strain of IAV designated as "S/Manitoba/647/67" was characterized using IAV antisera [234]. The first report of H1N1 virus in Canadian swine appeared in Quebec during 1980s-1990s when five genotypes of H1N1 virus were identified [235]. Since then several studies have reported H1N1, H1N2 and H3N2 viruses in Canadian swine [236][237][238][239][240][241][242][243].…”