Pathogenesis of West Nile Virus Lineage 2 in Domestic Geese after Experimental Infection

Abstract

West Nile virus (WNV) is an emerging infectious pathogen circulating between mosquitoes and birds but also infecting mammals. WNV has become autochthonous in Germany, causing striking mortality rates in avifauna and occasional diseases in humans and horses. We therefore wanted to assess the possible role of free-ranging poultry in the WNV transmission cycle and infected 15 goslings with WNV lineage 2 (German isolate). The geese were monitored daily and sampled regularly to determine viremia, viral shedding, and antibody development by molecular and serological methods. Geese were euthanized at various time points post-infection (pi). All infected geese developed variable degrees of viremia from day 1 to day 10 (maximum) and actively shed virus from days 2 to 7 post-infection. Depending on the time of death, the WN viral genome was detected in all examined tissue samples in at least one individual by RT-qPCR and viable virus was even re-isolated, except for in the liver. Pathomorphological lesions as well as immunohistochemically detectable viral antigens were found mainly in the brain. Furthermore, all of the geese seroconverted 6 days pi at the latest. In conclusion, geese are presumably not functioning as important amplifying hosts but are suitable sentinel animals for WNV surveillance.

A Prior Usutu Virus Infection Can Protect Geese from Severe West Nile Disease

“…Exceptions were the lungs and livers, which already contained only a few RNA copies when mono-infected with WNV. The overall milder disease course observed in most of the birds compared to the previously published WNV mono-infection [36] is consistent with human cases, in which WNV infections, secondary to USUV infections, have been shown to be asymptomatic or to exhibit only mild symptoms [30]. This is also corroborated by the results of the histopathological examination in the present study; neither encephalomalacia nor necrotic myocarditis nor lesions of a systemic vasculitis were detectable in the geese.…”

“…These results demonstrate that USUV successfully infected the geese by causing viremia and spreading to lymphatic organs, such as the spleen. Moreover, the distinct ganglioneuritis shown in the ENS early rather than late in the incubation period clearly indicates a crucial role of the vegetative nervous system in the early pathogenesis of the disease, as was already discussed for WNV [33,36]. Hence, USUV infection must also be added to the list of possible differential diagnoses associated with acute non-suppurative ganglioneuritis of the ENS in birds.…”

“…Also, the ratio of the WNV infected geese without viral copies in their swabs after USUV infection was higher than for the WNV mono-infected geese (2-7 dpi RR oropharyngeal and cloacal > 1, Table S11). Comparative illustration of RT-qPCR results of the blood cruors from WNV mono-infe geese (from a previous experiment, published in [36]) in blue dots, and from USUV and su quently WNV-infected geese in pink triangles. Both the total number of geese and the numbe geese tested per day were similar in both experiments, and negative results are not depicted.…”

“…Correspondingly, after the WNV infection, all samples were negative according to the USUV RT-qPCR (Tables S3, S5, and S6). Comparative illustration of WNV RT-qPCR results of organs from WNV mono-infected geese (from a previous experiment [36]) in dots, and from USUV-and subsequently WNV-infected geese in triangles. (a) Brain and feather pulp; (b) spleen and heart; (c) bursa fabricii and kidney; and (d) liver and lung samples.…”

“…Comparative illustration of WNV RT-qPCR results of the oropharyngeal (a) and clo (b) swab samples from WNV mono-infected geese (from a previous experiment [36]) in blue d Figure 8. Comparative illustration of WNV RT-qPCR results of the oropharyngeal (a) and cloacal (b)swab samples from WNV mono-infected geese (from a previous experiment[36]) in blue dots, and from WNV-infected geese after USUV infection in pink triangles. Both the total number of geese and the number of geese tested per day were similar in both experiments, and negative results are not depicted.…”