Detection of antibodies against influenza D virus in swine veterinarians in Italy in 2004

Abstract

Influenza D virus (IDV) was first isolated from a swine with respiratory disease symptoms in 2011 in the United States. Epidemiological and serological studies support the hypothesis that cattle represent the natural reservoir of IDV with periodical spillover events to other animal hosts. Little is known about the seroprevalence in humans and in specific target groups such as veterinarians in Italy. This study was designed to assess the prevalence of antibodies against two influenza D lineages (D/660 and D/OK) in Italy in archived serum samples from veterinarians working with swine collected in 2004. Serum samples were tested by haemagglutination inhibition (HI) and virus neutralization (VN) assays. Results showed that 4.88% (4/82) of tested samples were positive for D/660 and 2.44% (2/82) for D/OK by HI assay. Three out of four samples showed positivity when tested by VN

Serological Evidence for Circulation of Influenza D Virus in the Ovine Population in Italy

“…Overall, studies based on HI might tend to underestimate the prevalence of IDV. Similar inconsistencies have been reported in studies conducted in small ruminants and humans [ 11 , 14 ]. In contrast, a study in horses in the USA reported a strong agreement between the HI and VN seroprevalence data [ 12 ].…”

“…The presence of IDV has been reported globally, either directly or indirectly, in livestock animals [ 5 ], feral pigs and wild boars [ 6 , 7 ], camelids [ 8 ], small ruminants [ 9 , 10 , 11 ], and horses [ 12 ]. Abs specific to IDV have been also identified in humans [ 13 ], chiefly in workers with occupational exposure, i.e., veterinarians and farmers [ 14 , 15 ]. Although IDV was first isolated from pigs, cattle are presently considered as IDV’s main host and reservoir [ 16 ].…”

The Activation of the RIG-I/MDA5 Signaling Pathway upon Influenza D Virus Infection Impairs the Pulmonary Proinflammatory Response Triggered by Mycoplasma bovis Superinfection

“…These include the influenza D virus (IDV), a novel Orthomyxoviridae isolated in 2011 from swine with influenza-like illness ( 16 ). IDV exposure was documented in humans by serologic studies ( 17 – 19 ) and in several animal species ( 20 – 24 ), but cattle are considered its primary host ( 25 ). In the last few years, IDV detection in clinical samples has been positively associated with respiratory disease in cattle through metagenomic approaches ( 26 , 27 ).…”

Influenza Viruses and Vaccines: The Role of Vaccine Effectiveness Studies for Evaluation of the Benefits of Influenza Vaccines

“…However, both epidemiological and serological studies support the hypothesis that cattle are the natural reservoir. To date there is no direct evidence of IDV disease in humans, but antibodies against IDV have been detected, underlining the potential ability of this virus to infect and elicit an immune response in humans and especially in people working with animals and/or exposed to cattle [ 15 , 16 , 17 , 18 , 19 , 20 ].…”