Human Infection with Eurasian Avian-like Influenza A(H1N1) Virus, China

Avian-Like A (H1N1) Swine Influenza Virus Antibodies among Swine Farm Residents and Pigs in Southern China

“…It has been assumed that obvious antigenic and genetic differences exist between the avian-like A (H1N1) SIV and seasonal influenza H1N1 viruses. Previous studies have shown that little cross-reactivity does exist between these viruses (5,8,17); however, 17 of the HI-positive serum samples in the present study showed reactivity toward A/Brisbane/59/2007(H1N1), which could likely reflect a certain level of cross-reactivity among the samples, thereby complicating the interpretation of the HI test results. Furthermore, the study did not allow the evaluation of the association between seropositivity and clinical symptoms because a large proportion of swine influenza cases in humans are mild or even asymptomatic.…”

“…Zoonotic infections of humans with avian-like A (H1N1) SIVs were first identified in Europe, and since then, such cases have been reported several times in various locations worldwide (2)(3)(4). In China, it was recently reported for the first time that a 3-year-old boy in Hebei Province was infected with an EA A (H1N1) SIV (5). Another 3-year-old patient was reported to be infected with the EA H1N1 influenza virus A/Jiangsu/1/2011(JS11) in early 2011 (6).…”

Prevalence, genetics, and transmissibility in ferrets of Eurasian avian-like H1N1 swine influenza viruses

“…Although we cannot attribute the seropositivity of humans against H1N1 viruses to vaccination or natural infection, the overall seropositive rate to the EAH1N1 SIVs in humans is low. Two doses of the seasonal trivalent inactivated influenza vaccine could not substantially improve the levels of crossreactive antibodies to the EAH1N1 virus in humans (10). Thus, preexisting immunity in humans may not be sufficient to overcome EAH1N1 SIV infection.…”

“…The classical H1N1 SIVs emerged in humans as a reassortant (2009/H1N1) and caused the 2009 H1N1 influenza pandemic (5). The EAH1N1 SIVs have been detected in pigs in many Eurasian countries (6) and have caused several human infections in European countries and also in China (7)(8)(9)(10)(11), where a fatal case was reported (11). EAH1N1 SIVs are reported to be most prevalent in pigs that have been brought into Hong Kong since 2005 (12).…”

Protective efficacy of an inactivated Eurasian avian-like H1N1 swine influenza vaccine against homologous H1N1 and heterologous H1N1 and H1N2 viruses in mice

“…Sporadic human infection with the EA H1N1 SIV has been reported in Europe and China [9][10][11]. Moreover, our recent study showed that the EA H1N1 viruses have obtained traits that could cause a human influenza pandemic after long-term evolution in pigs [6].…”