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Topic: Novel Swine Influenza Virus
Posted: April 25 2009 at 12:37pm

CDC Emerging Infectious Diseases

page posted April 6, 2006

Research

Novel Swine Influenza Virus Subtype H3N1, United States

Porntippa Lekcharoensuk,*¹ Kelly M. Lager,* Ramesh Vemulapalli,† Mary Woodruff,† Amy L. Vincent,* and Jürgen A. Richt*
*US Department of Agriculture, Ames, Iowa, USA; and †Purdue University, West Lafayette, Indiana, USA

We report the emergence and characterization of a novel H3N1 subtype of swine influenza virus (SIV) in the United States.

Phylogenetic analysis showed that the H3N1 SIVs may have acquired the hemagglutinin gene from an H3N2 turkey isolate, the neuraminidase gene from a human H1N1 isolate, and the remaining genes from currently circulating SIVs.

The H3N1 SIVs were antigenically related to the turkey virus. Lung lesions and nasal shedding occurred in swine infected with the H3N1 SIVs, suggesting the potential to transmit among swine and to humans. Further surveillance will help determine whether this novel subtype will continue to circulate in swine populations.

http://www.cdc.gov/ncidod/eid/vol12no05/05-1060.htm

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Posted: April 25 2009 at 12:45pm

2006, American Society for Microbiology

Isolation and Genetic Characterization of New Reassortant H3N1 Swine Influenza Virus from Pigs in the Midwestern United States

Influenza viruses currently circulating in North American swine are

subtypes H1N1, H3N2, and H1N2 (11).

The classical H1N1 viruses have been circulating in the swine population since the Spanish flu pandemic of 1918 (1). The first SIV, A/SW/IA/15/30, was isolated in 1930 and is antigenically similar to the 1918 human influenza virus (12).

From 1930 to 1998, classic H1N1 viruses were the predominantly isolated subtype from US swine. In 1998, a new SIV subtype H3N2 emerged and became established in the North American swine population (13,14).

Genetic analysis showed that it was a

triple reassortant virus

containing genes from swine, human, and avian influenza viruses.

The H3N2 SIV acquired the polymerase basic (PB) protein 1, HA, and neuraminidase (NA) genes from a recent human virus,

the PB2 and polymerase acidic (PA) protein genes from avian viruses, and

the nucleocapsid protein (NP), matrix (M), and nonstructural (NS) genes from the classic H1N1 swine virus (13–16).

A year later, reassortment between the H3N2 and classic H1N1 SIV resulted in a new subtype

H1N2,

where the HA of the H3N2 subtype was replaced by the HA from the classic H1N1 virus (17).

This H1N2 subtype caused respiratory disease in swine and continues to circulate in swine populations (18).

Recently, wholly avian influenza viruses,

subtypes

H4N6 (5),

H3N3, and

H1N1 (19),

from water fowl were isolated from diseased swine in Canada; however, no evidence shows that these viruses can be successfully maintained in swine populations.

We identified and characterized a new SIV subtype H3N1 that may have arisen from reassortment of an H3N2 turkey isolate, a human H1N1 isolate, and currently circulating swine influenza viruses.

abstract here-

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1472084

.............................

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Posted: April 25 2009 at 2:43pm

Seroprevalence of H1N1, H3N2 and H1N2 Influenza Viruses in Pigs in Seven European Countries in 2002-2003

Kristien Van Reeth; Ian H. Brown; Ralf Dürrwald; Emanuela Foni; Geoffrey Labarque; Patrick Lenihan; Jaime Maldonado; Iwona Markowska-Daniel; Maurice Pensaert; Zdenek Pospisil; Guus Koch

Authors and Disclosures

Published: 06/18/2008

excerpt

.Veterinary Laboratories Agency, Weybridge, UK, unpublished observations; Kuntz-Simon G., Agence Française de Sécurité Sanitaire des Aliments, Ploufragan, France, personal communication).

Either or both subtypes have also been reported in Bulgaria, the former Czechoslovakia, Greece, Hungary, Ireland, Macedonia, Poland and Sweden.[13]

As for the H1N2 virus, a limited serosurvey in sows in Belgium in 1999 has shown seropositivity in 69% of the 443 sera examined.[7] However, there is limited H1N2 seroprevalence data for other European countries and there is little information on the evolution of H1N1 or H3N2 seroprevalence rates in Europe.

The epidemiology of swine influenza (SI) has become increasingly complex over the last decade. Three influenza A virus subtypes - H1N1, H3N2 and H1N2 - are currently circulating in swine worldwide, but the origins and the antigenic and genetic characteristics of these swine influenza virus (SIV) subtypes differ in different continents or regions of the world.[1]

The first significant outbreaks of SI on the European mainland occurred in the late 1970s after the transmission of an H1N1 virus from wild ducks to pigs.[2] This 'avian-like' H1N1 virus has become established in the European pig population and ultimately became the dominant H1N1 SIV strain.[3]

Viruses of human origin, A/Hong Kong/68-like H3N2 formed a stable lineage in European pigs since the early 1970s, but reassortant H3N2 viruses with human haemagglutinin (HA) and neuraminidase (NA) genes and avian-like swine H1N1 internal protein genes have become dominant since the mid 1980s.[4,5]

Finally, 'triple reassortant' H1N2 viruses have been isolated frequently from pigs throughout Europe since the mid 1990s.[6-10] These viruses contain an HA of human influenza virus origin, a NA of swine H3N2 virus origin and internal protein genes of avian-like swine H1N1 virus origin.[11]

The HA of these H1N2 viruses shows low antigenic and genetic homology (70·4% amino acid identity in the HA1 region) with avian-like H1N1 viruses and there is no cross-reaction between H1N1 and H1N2 viruses in the HI test.[12]

Though most Swinw Iinfluenza Virus infections are clinically mild or subclinical, all three subtypes have been associated frequently with typical outbreaks of 'swine flu' and SIV may be responsible for up to 50% of acute respiratory disease outbreaks in pigs.[1]

http://www.medscape.com/viewarticle/574904

....................

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Guests Members Profile Send Private Message Find Members Posts Add to Buddy List Guest Group	Post Options Post Reply Quote Guests Thanks(0) Quote Reply Topic: Novel Swine Influenza Virus Posted: April 25 2009 at 12:37pm
	. CDC Emerging Infectious Diseases page posted April 6, 2006 *Research* Novel Swine Influenza Virus Subtype H3N1, United States Porntippa Lekcharoensuk,¹ Kelly M. Lager, Ramesh Vemulapalli,† Mary Woodruff,† Amy L. Vincent,* and Jürgen A. Richt* *US Department of Agriculture, Ames, Iowa, USA; and †Purdue University, West Lafayette, Indiana, USA We report the emergence and characterization of a novel H3N1 subtype of swine influenza virus (SIV) in the United States. Phylogenetic analysis showed that the H3N1 SIVs may have acquired the hemagglutinin gene from an H3N2 turkey isolate, the neuraminidase gene from a human H1N1 isolate, and the remaining genes from currently circulating SIVs. The H3N1 SIVs were antigenically related to the turkey virus. Lung lesions and nasal shedding occurred in swine infected with the H3N1 SIVs, suggesting the potential to transmit among swine and to humans. Further surveillance will help determine whether this novel subtype will continue to circulate in swine populations. http://www.cdc.gov/ncidod/eid/vol12no05/05-1060.htm

Guests Members Profile Send Private Message Find Members Posts Add to Buddy List Guest Group	Post Options Post Reply Quote Guests Thanks(0) Quote Reply Posted: April 25 2009 at 12:45pm
	2006, American Society for Microbiology Isolation and Genetic Characterization of New Reassortant H3N1 Swine Influenza Virus from Pigs in the Midwestern United States Influenza viruses currently circulating in North American swine are subtypes H1N1, H3N2, and H1N2 (11). The classical H1N1 viruses have been circulating in the swine population since the Spanish flu pandemic of 1918 (1). The first SIV, A/SW/IA/15/30, was isolated in 1930 and is antigenically similar to the 1918 human influenza virus (12). From 1930 to 1998, classic H1N1 viruses were the predominantly isolated subtype from US swine. In 1998, a new SIV subtype H3N2 emerged and became established in the North American swine population (13,14). Genetic analysis showed that it was a triple reassortant virus containing genes from swine, human, and avian influenza viruses. The H3N2 SIV acquired the polymerase basic (PB) protein 1, HA, and neuraminidase (NA) genes from a recent human virus, the PB2 and polymerase acidic (PA) protein genes from avian viruses, and the nucleocapsid protein (NP), matrix (M), and nonstructural (NS) genes from the classic H1N1 swine virus (13–16). A year later, reassortment between the H3N2 and classic H1N1 SIV resulted in a new subtype H1N2, where the HA of the H3N2 subtype was replaced by the HA from the classic H1N1 virus (17). This H1N2 subtype caused respiratory disease in swine and continues to circulate in swine populations (18). Recently, wholly avian influenza viruses, subtypes H4N6 (5), H3N3, and H1N1 (19), from water fowl were isolated from diseased swine in Canada; however, no evidence shows that these viruses can be successfully maintained in swine populations. We identified and characterized a new SIV subtype H3N1 that may have arisen from reassortment of an H3N2 turkey isolate, a human H1N1 isolate, and currently circulating swine influenza viruses. abstract here- http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1472084 .............................

Guests Members Profile Send Private Message Find Members Posts Add to Buddy List Guest Group	Post Options Post Reply Quote Guests Thanks(0) Quote Reply Posted: April 25 2009 at 2:43pm
	Seroprevalence of H1N1, H3N2 and H1N2 Influenza Viruses in Pigs in Seven European Countries in 2002-2003 Kristien Van Reeth; Ian H. Brown; Ralf Dürrwald; Emanuela Foni; Geoffrey Labarque; Patrick Lenihan; Jaime Maldonado; Iwona Markowska-Daniel; Maurice Pensaert; Zdenek Pospisil; Guus Koch Authors and Disclosures Published: 06/18/2008 excerpt .Veterinary Laboratories Agency, Weybridge, UK, unpublished observations; Kuntz-Simon G., Agence Française de Sécurité Sanitaire des Aliments, Ploufragan, France, personal communication). Either or both subtypes have also been reported in Bulgaria, the former Czechoslovakia, Greece, Hungary, Ireland, Macedonia, Poland and Sweden.[13] As for the H1N2 virus, a limited serosurvey in sows in Belgium in 1999 has shown seropositivity in 69% of the 443 sera examined.[7] However, there is limited H1N2 seroprevalence data for other European countries and there is little information on the evolution of H1N1 or H3N2 seroprevalence rates in Europe. The epidemiology of swine influenza (SI) has become increasingly complex over the last decade. Three influenza A virus subtypes - H1N1, H3N2 and H1N2 - are currently circulating in swine worldwide, but the origins and the antigenic and genetic characteristics of these swine influenza virus (SIV) subtypes differ in different continents or regions of the world.[1] The first significant outbreaks of SI on the European mainland occurred in the late 1970s after the transmission of an H1N1 virus from wild ducks to pigs.[2] This 'avian-like' H1N1 virus has become established in the European pig population and ultimately became the dominant H1N1 SIV strain.[3] Viruses of human origin, A/Hong Kong/68-like H3N2 formed a stable lineage in European pigs since the early 1970s, but reassortant H3N2 viruses with human haemagglutinin (HA) and neuraminidase (NA) genes and avian-like swine H1N1 internal protein genes have become dominant since the mid 1980s.[4,5] Finally, 'triple reassortant' H1N2 viruses have been isolated frequently from pigs throughout Europe since the mid 1990s.[6-10] These viruses contain an HA of human influenza virus origin, a NA of swine H3N2 virus origin and internal protein genes of avian-like swine H1N1 virus origin.[11] The HA of these H1N2 viruses shows low antigenic and genetic homology (70·4% amino acid identity in the HA1 region) with avian-like H1N1 viruses and there is no cross-reaction between H1N1 and H1N2 viruses in the HI test.[12] Though most Swinw Iinfluenza Virus infections are clinically mild or subclinical, all three subtypes have been associated frequently with typical outbreaks of 'swine flu' and SIV may be responsible for up to 50% of acute respiratory disease outbreaks in pigs.[1] http://www.medscape.com/viewarticle/574904 ....................