Recent Influenza A (H1N1) Infections of Pigs and Turkeys in Northern Europe

doi:10.1006/viro.1994.1344

Virology

Volume 202, Issue 1, July 1994, Pages 281-286

https://doi.org/10.1006/viro.1994.1344 Get rights and content

Abstract

The most recent introduction of an avian influenza A virus without reassortment into mammals occurred in 1979 when H1N1 strains could be isolated from diseased pigs in northern Europe. This newly introduced avian virus formed a stable lineage in pigs and, in the meantime, spread all over Europe. In 1991 highly pathogenic H1N1 strains closely related to a contemporary swine virus were isolated from turkeys of a breeding farm near Bremen, Germany. Outbreaks in several farms in Germany, France, and the Netherlands indicate that the "avian-like" swine viruses can easily be reintroduced into an avian population causing severe economical losses.

References (0)

Cited by (47)

Enhanced replication of swine influenza viruses in dexamethasone-treated juvenile and layer turkeys
2013, Veterinary Microbiology
Citation Excerpt :
Due to close proximity of both swine and turkey production in the U.S., SIV infection in turkeys has been related to the prevalence and predominant strains circulating in the swine population. For instance, the classical swine H1N1 SIV had been the predominant subtype circulating in the U.S. swine population till the late 1990s and was the most frequently reported influenza subtype transmitted to turkey populations (Andral et al., 1985; Ficken et al., 1989; Ludwig et al., 1994; Mohan et al., 1981). Similarly, a few years after the emergence and predominance of the triple reassortant (TR) H3N2 SIVs in the swine population in the U.S., it has been frequently transmitted to turkey populations causing severe egg production problems (Webby et al., 2000).
Frequent transmission of swine influenza viruses (SIVs) to turkeys has been reported since 1980s. Experimental studies also showed that SIVs can infect turkeys with varying replication and transmission efficiency depending on the strain. However, host factors involved in infection/replication efficiency remain unclear. To investigate whether the immune status of turkeys might play a role in the susceptibility of turkeys to SIVs, we studied the replication efficiency of two recent SIVs (human-like H1N2 and triple reassortant (TR) H3N2) in dexamethasone-treated turkeys. The viruses were inoculated intranasally in both dexamethasone-treated and untreated control juvenile and layer turkeys. Amount of virus shedding was monitored at 2, 4, and 7 days post inoculation (DPI). Additionally, passage of both viruses was attempted in dexamethasone-treated 4-week-old turkeys. In both juvenile and layer turkeys, we were able to detect human-like H1N2 SIV only from dexamethasone-treated turkeys and no virus was detected in untreated birds. The virus shedding of the TR H3N2 SIV was also consistently higher (≈1 Log₁₀ EID₅₀/ml) in dexamethasone-treated birds in both tracheal and cloacal swabs compared to untreated birds. Virus passage in dexamethasone-treated turkeys was successful up to the second passage and no virus was recovered from the third passage. These results show that potential immunosuppression due to dexamethasone treatment may enhance the transmission and adaptation of SIVs in turkeys through enhancement of virus replication, prolonged virus shedding, and possible decrease of infectious dose required to initiate infection.
Pathobiology of triple reassortant H3N2 influenza viruses in breeder turkeys and its potential implication for vaccine studies in turkeys
2009, Vaccine
Citation Excerpt :
In breeder turkeys, low pathogenic influenza A infections almost always result in decreased egg production. Several previous reports document drops in egg production in turkeys due to H1N1 [20,21], reassortant H1N2 [18], and H3N2 viruses [11,12,22] from different parts of the world. TR H3N2 viruses have been associated with sudden declines in egg production in breeder turkeys within the U.S. [11,12].
Triple reassortant (TR) H3N2 influenza viruses have been isolated from turkeys in the United States since 2003. These TR H3N2 virus infections have been associated with drastic declines in egg production in breeder turkeys although co-infection with multiple agents could have been responsible for exacerbating the clinical signs. In this study, we experimentally confirmed that TR H3N2 influenza virus alone can cause drastic reduction/complete cessation of egg production and pathology of the reproductive tract in 26-week-old breeder turkeys. We confirmed high levels of virus replication and abundant distribution of avian specific α2,3 sialic acid-galactose receptors in the oviduct of these turkeys. Although 2–6-week-old turkeys are routinely used for pathogenicity and vaccine protection studies, the low levels of viral shedding and asymptomatic infections in this age group often pose difficulty in interpretation of results. Our study shows that breeder turkeys should be used to assess the potential pathogenicity of TR H3N2 viruses and the viral titers and pathology of the oviduct as well as egg production data can be good measures of protection following in vivo challenge in vaccine efficacy studies.
Modeling the spread of bird flu and predicting outbreak diversity
2008, Nonlinear Analysis: Real World Applications
Avian influenza, commonly known as bird flu, is an epidemic caused by H5N1 virus that primarily affects birds like chickens, wild water birds, etc. On rare occasions, these can infect other species including pigs and humans. In the span of less than a year, the lethal strain of bird flu is spreading very fast across the globe mainly in South East Asia, parts of Central Asia, Africa and Europe. In order to study the patterns of spread of epidemic, we made an investigation of outbreaks of the epidemic in one week, that is from February 13–18, 2006, when the deadly virus surfaced in India. We have designed a statistical transmission model of bird flu taking into account the factors that affect the epidemic transmission such as source of infection, social and natural factors and various control measures are suggested. For modeling the general intensity coefficient $f (r)$ , we have implemented the recent ideas given in the article Fitting the Bill, Nature [R. Howlett, Fitting the bill, Nature 439 (2006) 402], which describes the geographical spread of epidemics due to transportation of poultry products. Our aim is to study the spread of avian influenza, both in time and space, to gain a better understanding of transmission mechanism. Our model yields satisfactory results as evidenced by the simulations and may be used for the prediction of future situations of epidemic for longer periods. We utilize real data at these various scales and our model allows one to generalize our predictions and make better suggestions for the control of this epidemic.
Genetic and antigenic relatedness of H3 subtype influenza A viruses isolated from avian and mammalian species
2008, Vaccine
Citation Excerpt :
Pigs have been hypothesized to play a key role in the interspecies transmission of influenza A viruses by means of antigenic shift [11,34]. Interspecies transmission of H1N1 and H3N2 viruses between pigs and turkeys has been reported in multiple occasions [18,35–37]. The geographic proximity of swine and turkey operations in the U.S., especially in the Midwest part of the country, caused a situation that required producers to vaccinate their turkey breeders with swine viruses that are circulating in the field.
In 2004, we isolated triple reassortant H3N2 influenza viruses from turkey breeder hens in Ohio and Illinois. The Illinois flock was vaccinated twice with an inactivated H3N2 vaccine containing a swine origin virus before the outbreak. Additionally, a commercial inactivated vaccine containing an H3N4 virus of duck origin is being used in some turkey breeders. This prompted us to initiate a comparative study on the antigenic and genetic relatedness of various H3 subtype influenza viruses isolated from turkeys, ducks, pigs and humans. The antigenic relatedness between the different viruses was evaluated with the Archetti and Horsfall formula, while nucleotide genetic similarities were calculated using pairwise alignments. Results obtained indicated a high degree of antigenic (>90%) and genetic (>99%) similarities among the turkey-origin H3N2 viruses. However, the turkey viruses were antigenically distantly related to the swine-origin vaccine virus (<30%), although they had approximately 95% genetic similarity in the HA1 gene. Additionally, major genetic and antigenic changes were observed between the turkey viruses and the H3N4 duck vaccine virus as well as the H3N2 human virus. Such genetic and antigenic differences between the turkey-origin viruses and other H3 subtype viruses including vaccine strains could be the reason for the failure in protection in the Illinois turkey breeders vaccinated with swine origin virus. This also emphasizes the importance of using viruses for vaccines that are antigenically similar to the field strains.
Influenza viruses
2019, Diseases of Swine
Demographic and production practices of pig producers trading at saleyards in eastern Australia
2013, Australian Veterinary Journal

View all citing articles on Scopus

View full text

Regular ArticleRecent Influenza A (H1N1) Infections of Pigs and Turkeys in Northern Europe

Abstract

Regular Article
Recent Influenza A (H1N1) Infections of Pigs and Turkeys in Northern Europe