Mosquito-Independent Transmission of West Nile virus in Farmed Saltwater Crocodiles (<i>Crocodylus porosus</i>)
West Nile virus, Kunjin strain (WNV<sub>KUN</sub>) is endemic in Northern Australia, but rarely causes clinical disease in humans and horses. Recently, WNV<sub>KUN</sub> genomic material was detected in cutaneous lesions of farmed saltwater crocodiles (<i>Crocodylus por...
| Main Authors: | , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-02-01
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| Series: | Viruses |
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| Online Access: | https://www.mdpi.com/1999-4915/12/2/198 |
| _version_ | 1819103684860051456 |
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| author | Gervais Habarugira Jasmin Moran Agathe M.G. Colmant Steven S. Davis Caitlin A. O’Brien Sonja Hall-Mendelin Jamie McMahon Glen Hewitson Neelima Nair Jean Barcelon Willy W. Suen Lorna Melville Jody Hobson-Peters Roy A. Hall Sally R. Isberg Helle Bielefeldt-Ohmann |
| author_facet | Gervais Habarugira Jasmin Moran Agathe M.G. Colmant Steven S. Davis Caitlin A. O’Brien Sonja Hall-Mendelin Jamie McMahon Glen Hewitson Neelima Nair Jean Barcelon Willy W. Suen Lorna Melville Jody Hobson-Peters Roy A. Hall Sally R. Isberg Helle Bielefeldt-Ohmann |
| author_sort | Gervais Habarugira |
| collection | DOAJ |
| description | West Nile virus, Kunjin strain (WNV<sub>KUN</sub>) is endemic in Northern Australia, but rarely causes clinical disease in humans and horses. Recently, WNV<sub>KUN</sub> genomic material was detected in cutaneous lesions of farmed saltwater crocodiles (<i>Crocodylus porosus</i>), but live virus could not be isolated, begging the question of the pathogenesis of these lesions. Crocodile hatchlings were experimentally infected with either 10<sup>5</sup> (<i>n</i> = 10) or 10<sup>4</sup> (<i>n</i> = 11) TCID<sub>50</sub>-doses of WNV<sub>KUN</sub> and each group co-housed with six uninfected hatchlings in a mosquito-free facility. Seven hatchlings were mock-infected and housed separately. Each crocodile was rotationally examined and blood-sampled every third day over a 3-week period. Eleven animals, including three crocodiles developing typical skin lesions, were culled and sampled 21 days post-infection (dpi). The remaining hatchlings were blood-sampled fortnightly until experimental endpoint 87 dpi. All hatchlings remained free of overt clinical disease, apart from skin lesions, throughout the experiment. Viremia was detected by qRT-PCR in infected animals during 2−17 dpi and in-contact animals 11−21 dpi, indicating horizontal mosquito-independent transmission. Detection of viral genome in tank-water as well as oral and cloacal swabs, collected on multiple days, suggests that shedding into pen-water and subsequent mucosal infection is the most likely route. All inoculated animals and some in-contact animals developed virus-neutralizing antibodies detectable from 17 dpi. Virus-neutralizing antibody titers continued to increase in exposed animals until the experimental endpoint, suggestive of persisting viral antigen. However, no viral antigen was detected by immunohistochemistry in any tissue sample, including from skin and intestine. While this study confirmed that infection of saltwater crocodiles with WNV<sub>KUN</sub> was associated with the formation of skin lesions, we were unable to elucidate the pathogenesis of these lesions or the nidus of viral persistence. Our results nevertheless suggest that prevention of WNV<sub>KUN</sub> infection and induction of skin lesions in farmed crocodiles may require management of both mosquito-borne and water-borne viral transmission in addition to vaccination strategies. |
| first_indexed | 2024-12-22T01:54:23Z |
| format | Article |
| id | doaj.art-4698d708abd1489b8056957588c28e52 |
| institution | Directory Open Access Journal |
| issn | 1999-4915 |
| language | English |
| last_indexed | 2024-12-22T01:54:23Z |
| publishDate | 2020-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Viruses |
| spelling | doaj.art-4698d708abd1489b8056957588c28e522022-12-21T18:42:50ZengMDPI AGViruses1999-49152020-02-0112219810.3390/v12020198v12020198Mosquito-Independent Transmission of West Nile virus in Farmed Saltwater Crocodiles (<i>Crocodylus porosus</i>)Gervais Habarugira0Jasmin Moran1Agathe M.G. Colmant2Steven S. Davis3Caitlin A. O’Brien4Sonja Hall-Mendelin5Jamie McMahon6Glen Hewitson7Neelima Nair8Jean Barcelon9Willy W. Suen10Lorna Melville11Jody Hobson-Peters12Roy A. Hall13Sally R. Isberg14Helle Bielefeldt-Ohmann15School of Veterinary Science, University of Queensland, Gatton, Qld 4343, AustraliaCentre for Crocodile Research, Noonamah, NT 0837, AustraliaSchool of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Qld 4072, AustraliaBerrimah Veterinary Laboratories, NT 0828, AustraliaSchool of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Qld 4072, AustraliaQueensland Health, Forensic and Scientific Services, Public Health Virology, Coopers Plains, Qld 4108, AustraliaQueensland Health, Forensic and Scientific Services, Public Health Virology, Coopers Plains, Qld 4108, AustraliaQueensland Health, Forensic and Scientific Services, Public Health Virology, Coopers Plains, Qld 4108, AustraliaQueensland Health, Forensic and Scientific Services, Public Health Virology, Coopers Plains, Qld 4108, AustraliaQueensland Health, Forensic and Scientific Services, Public Health Virology, Coopers Plains, Qld 4108, AustraliaSchool of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Qld 4072, AustraliaBerrimah Veterinary Laboratories, NT 0828, AustraliaSchool of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Qld 4072, AustraliaSchool of Chemistry and Molecular Biosciences, University of Queensland, St Lucia, Qld 4072, AustraliaCentre for Crocodile Research, Noonamah, NT 0837, AustraliaSchool of Veterinary Science, University of Queensland, Gatton, Qld 4343, AustraliaWest Nile virus, Kunjin strain (WNV<sub>KUN</sub>) is endemic in Northern Australia, but rarely causes clinical disease in humans and horses. Recently, WNV<sub>KUN</sub> genomic material was detected in cutaneous lesions of farmed saltwater crocodiles (<i>Crocodylus porosus</i>), but live virus could not be isolated, begging the question of the pathogenesis of these lesions. Crocodile hatchlings were experimentally infected with either 10<sup>5</sup> (<i>n</i> = 10) or 10<sup>4</sup> (<i>n</i> = 11) TCID<sub>50</sub>-doses of WNV<sub>KUN</sub> and each group co-housed with six uninfected hatchlings in a mosquito-free facility. Seven hatchlings were mock-infected and housed separately. Each crocodile was rotationally examined and blood-sampled every third day over a 3-week period. Eleven animals, including three crocodiles developing typical skin lesions, were culled and sampled 21 days post-infection (dpi). The remaining hatchlings were blood-sampled fortnightly until experimental endpoint 87 dpi. All hatchlings remained free of overt clinical disease, apart from skin lesions, throughout the experiment. Viremia was detected by qRT-PCR in infected animals during 2−17 dpi and in-contact animals 11−21 dpi, indicating horizontal mosquito-independent transmission. Detection of viral genome in tank-water as well as oral and cloacal swabs, collected on multiple days, suggests that shedding into pen-water and subsequent mucosal infection is the most likely route. All inoculated animals and some in-contact animals developed virus-neutralizing antibodies detectable from 17 dpi. Virus-neutralizing antibody titers continued to increase in exposed animals until the experimental endpoint, suggestive of persisting viral antigen. However, no viral antigen was detected by immunohistochemistry in any tissue sample, including from skin and intestine. While this study confirmed that infection of saltwater crocodiles with WNV<sub>KUN</sub> was associated with the formation of skin lesions, we were unable to elucidate the pathogenesis of these lesions or the nidus of viral persistence. Our results nevertheless suggest that prevention of WNV<sub>KUN</sub> infection and induction of skin lesions in farmed crocodiles may require management of both mosquito-borne and water-borne viral transmission in addition to vaccination strategies.https://www.mdpi.com/1999-4915/12/2/198west nile virussaltwater crocodilewater-borne transmission |
| spellingShingle | Gervais Habarugira Jasmin Moran Agathe M.G. Colmant Steven S. Davis Caitlin A. O’Brien Sonja Hall-Mendelin Jamie McMahon Glen Hewitson Neelima Nair Jean Barcelon Willy W. Suen Lorna Melville Jody Hobson-Peters Roy A. Hall Sally R. Isberg Helle Bielefeldt-Ohmann Mosquito-Independent Transmission of West Nile virus in Farmed Saltwater Crocodiles (<i>Crocodylus porosus</i>) Viruses west nile virus saltwater crocodile water-borne transmission |
| title | Mosquito-Independent Transmission of West Nile virus in Farmed Saltwater Crocodiles (<i>Crocodylus porosus</i>) |
| title_full | Mosquito-Independent Transmission of West Nile virus in Farmed Saltwater Crocodiles (<i>Crocodylus porosus</i>) |
| title_fullStr | Mosquito-Independent Transmission of West Nile virus in Farmed Saltwater Crocodiles (<i>Crocodylus porosus</i>) |
| title_full_unstemmed | Mosquito-Independent Transmission of West Nile virus in Farmed Saltwater Crocodiles (<i>Crocodylus porosus</i>) |
| title_short | Mosquito-Independent Transmission of West Nile virus in Farmed Saltwater Crocodiles (<i>Crocodylus porosus</i>) |
| title_sort | mosquito independent transmission of west nile virus in farmed saltwater crocodiles i crocodylus porosus i |
| topic | west nile virus saltwater crocodile water-borne transmission |
| url | https://www.mdpi.com/1999-4915/12/2/198 |
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