Serological Evidence of Transmission of Human Influenza A and B Viruses to Caspian Seals (Phoca caspica)

Abstract

Seroepidemiological surveillance of influenza in Caspian seals (Phoca caspica) was conducted. Antibodies to influenza A virus were detected in 54% (7/13), 57% (4/7), 40% (6/15) and 26% (11/42) of the serum samples collected in 1993, 1997, 1998 and 2000 by enzyme‐linked immunosorbent assay (ELISA). In an hemagglutination‐inhibition (HI) test using H1‐H15 reference influenza A viruses as antigens, more than half of the examined ELISA‐positive sera reacted with an H3N2 prototype strain A/Aichi/2/68. These sera were then examined by HI test with a series of naturally occurring antigenic variants of human H3N2 virus, and H3 viruses of swine, duck, and equine origin. The sera reacted strongly with the A/Bangkok/1/79 (H3N2) strain, which was prevalent in humans in 1979–1981. The present results indicate that human A/Bangkok/1/79‐like virus was transmitted to Caspian seals probably in the early 1980s, and was circulated in the population. Antibodies to influenza B virus were detected by ELISA in 14% (1/7) and 10% (4/42) serum samples collected from Caspian seals in 1997 and 2000, respectively. Our findings indicate that seal might be a reservoir of both influenza A and B viruses originated from humans.

Age-Associated Change in the Frequency of Memory CD4+ T Cells Impairs Long Term CD4+ T Cell Responses to Influenza Vaccine

“…Anti-influenza virus Abs in serum obtained from seven young and 11 elderly individuals before and 3 mo after vaccination were measured by ELISA as previously described (27), with some modifications. Briefly, 96-well microtiter plates (ICN Biomedicals, Aurora, OH) were coated overnight at 4°C with lysates of influenza virus (A/New Caledonia, A/Panama, and B/Hong Kong) in coating buffer at 1 g/ml.…”

Serological Evidence of Influenza A Virus Infection in Kuril Harbor Seals (Phoca vitulina stejnegeri) of Hokkaido, Japan

“…Therefore, it is possible that ELISA might show a positive for the virus without the subtype being identifiable by HI test. Previous serological studies on influenza A virus infection have shown that the same sample can test positive by ELISA but negative by HI test [22][23][24]. In this study, antibodies to H3 and H6 subtypes of influenza A virus were detected from sera collected from Kuril harbor seals at Nosappu.…”

“…Enzyme-linked immunosorbent assay (ELISA): ELISA was performed according to the modified procedure described previously [16,24]. Purified A/Aichi/2/68 (H3N2) virus was disrupted in 0.5 M Tris pH 7.8 containing 0.5% Triton X-100 and 0.6 M KCl and diluted to 2 µg/ml in phosphate-buffered saline (PBS).…”

“…All of these seal viruses were of avian origin [2,10,16,35]. Serological investigation of seals in the Bering Sea [6], Barents Sea [30], Alaska [5], Arctic Canada [22], Caspian Sea [24], Lake Baikal and Kara Sea [23] revealed viral infections.…”

Ferret airway epithelial cell cultures support efficient replication of influenza B virus but not mumps virus

“…Influenza B viruses isolated from seals and pigs were likely acquired by reverse zoonotic events (Bodewes et al, 2013;Ohishi et al, 2002;Osterhaus et al, 2000;Ran et al, 2015). Although several studies have described infection of ferrets with influenza type B viruses (Huang et al, 2014;Kim et al, 2009), we were interested in understanding at the cellular level how appropriate the ferret model is for the study of human influenza B viruses.…”