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The Nature of Exposure Drives Transmission of Nipah Viruses from Malaysia and Bangladesh in Ferrets.

Clayton BA, Middleton D, Arkinstall R, Frazer L, Wang LF, Marsh GA - PLoS Negl Trop Dis (2016)

Bottom Line: In contrast, all naïve ferrets developed acute infection following assisted and direct exposure to oronasal fluid from animals that were shedding either NiV-BD or NiV-MY.In contrast, active transfer of infected bodily fluids consistently results in transmission, regardless of the virus strain.These observations suggest that the risk of NiV transmission is underpinned by social and environmental factors, and will have practical implications for managing transmission risk during outbreaks of human disease.

View Article: PubMed Central - PubMed

Affiliation: Health and Biosecurity, Australian Animal Health Laboratory, Commonwealth Scientific and Industrial Research Organisation, Geelong, Victoria, Australia.

ABSTRACT
Person-to-person transmission is a key feature of human Nipah virus outbreaks in Bangladesh. In contrast, in an outbreak of Nipah virus in Malaysia, people acquired infections from pigs. It is not known whether this important epidemiological difference is driven primarily by differences between NiV Bangladesh (NiV-BD) and Malaysia (NiV-MY) at a virus level, or by environmental or host factors. In a time course study, ferrets were oronasally exposed to equivalent doses of NiV-BD or NiV-MY. More rapid onset of productive infection and higher levels of virus replication in respiratory tract tissues were seen for NiV-BD compared to NiV-MY, corroborating our previous report of increased oral shedding of NiV-BD in ferrets and suggesting a contributory mechanism for increased NiV-BD transmission between people compared to NiV-MY. However, we recognize that transmission occurs within a social and environmental framework that may have an important and differentiating role in NiV transmission rates. With this in mind, ferret-to-ferret transmission of NiV-BD and NiV-MY was assessed under differing viral exposure conditions. Transmission was not identified for either virus when naïve ferrets were cohoused with experimentally-infected animals. In contrast, all naïve ferrets developed acute infection following assisted and direct exposure to oronasal fluid from animals that were shedding either NiV-BD or NiV-MY. Our findings for ferrets indicate that, although NiV-BD may be shed at higher levels than NiV-MY, transmission risk may be equivalently low under exposure conditions provided by cohabitation alone. In contrast, active transfer of infected bodily fluids consistently results in transmission, regardless of the virus strain. These observations suggest that the risk of NiV transmission is underpinned by social and environmental factors, and will have practical implications for managing transmission risk during outbreaks of human disease.

No MeSH data available.


Related in: MedlinePlus

Intranasal lesions after exposure to NiV-BD or NiV-MY.(A) Viral antigen in inflamed nasopharyngeal epithelium and submucosal cells of a NiV-BD-infected ferret, d5pi. (B) Rare immunopositive staining in epithelium (arrow-head; enlarged in inset) and underlying lymphoid tissue in the pharynx of a NiV-MY-infected ferret, d5pi. (C) Viral antigen in the respiratory epithelium, submucosal cells and endothelium of the nasal cavity of a ferret exposed to NiV-BD, d7pi. (A), (B): 20x objective, scale bars 50 um; (C): 40x objective.
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pntd.0004775.g002: Intranasal lesions after exposure to NiV-BD or NiV-MY.(A) Viral antigen in inflamed nasopharyngeal epithelium and submucosal cells of a NiV-BD-infected ferret, d5pi. (B) Rare immunopositive staining in epithelium (arrow-head; enlarged in inset) and underlying lymphoid tissue in the pharynx of a NiV-MY-infected ferret, d5pi. (C) Viral antigen in the respiratory epithelium, submucosal cells and endothelium of the nasal cavity of a ferret exposed to NiV-BD, d7pi. (A), (B): 20x objective, scale bars 50 um; (C): 40x objective.

Mentions: Similarly for the URT, acute viral rhinitis and/or nasopharyngitis were manifest on d3pi in the NiV-BD group and from d5pi in the NiV-MY group (Fig 2). Epithelial cells positive for viral antigen were also seen in the hard and/or soft palates and trachea of animals infected with NiV-BD (Ferrets 2, 8, 11, 13) and NiV-MY (Ferret 24) late in the disease course. Interestingly, at the later time points there was also viral antigen in, variously, nasopharyngeal epithelium; nasopharyngeal submucosa including connective tissues (Ferret 21) and vascular endothelium; mucosal lymphoid tissue; and tracheal and soft palate stroma of animals infected with NiV-BD (Ferrets 8, 11, 13, 14) and NiV-MY (Ferrets 15, 20, 21, 24, 25).


The Nature of Exposure Drives Transmission of Nipah Viruses from Malaysia and Bangladesh in Ferrets.

Clayton BA, Middleton D, Arkinstall R, Frazer L, Wang LF, Marsh GA - PLoS Negl Trop Dis (2016)

Intranasal lesions after exposure to NiV-BD or NiV-MY.(A) Viral antigen in inflamed nasopharyngeal epithelium and submucosal cells of a NiV-BD-infected ferret, d5pi. (B) Rare immunopositive staining in epithelium (arrow-head; enlarged in inset) and underlying lymphoid tissue in the pharynx of a NiV-MY-infected ferret, d5pi. (C) Viral antigen in the respiratory epithelium, submucosal cells and endothelium of the nasal cavity of a ferret exposed to NiV-BD, d7pi. (A), (B): 20x objective, scale bars 50 um; (C): 40x objective.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4920392&req=5

pntd.0004775.g002: Intranasal lesions after exposure to NiV-BD or NiV-MY.(A) Viral antigen in inflamed nasopharyngeal epithelium and submucosal cells of a NiV-BD-infected ferret, d5pi. (B) Rare immunopositive staining in epithelium (arrow-head; enlarged in inset) and underlying lymphoid tissue in the pharynx of a NiV-MY-infected ferret, d5pi. (C) Viral antigen in the respiratory epithelium, submucosal cells and endothelium of the nasal cavity of a ferret exposed to NiV-BD, d7pi. (A), (B): 20x objective, scale bars 50 um; (C): 40x objective.
Mentions: Similarly for the URT, acute viral rhinitis and/or nasopharyngitis were manifest on d3pi in the NiV-BD group and from d5pi in the NiV-MY group (Fig 2). Epithelial cells positive for viral antigen were also seen in the hard and/or soft palates and trachea of animals infected with NiV-BD (Ferrets 2, 8, 11, 13) and NiV-MY (Ferret 24) late in the disease course. Interestingly, at the later time points there was also viral antigen in, variously, nasopharyngeal epithelium; nasopharyngeal submucosa including connective tissues (Ferret 21) and vascular endothelium; mucosal lymphoid tissue; and tracheal and soft palate stroma of animals infected with NiV-BD (Ferrets 8, 11, 13, 14) and NiV-MY (Ferrets 15, 20, 21, 24, 25).

Bottom Line: In contrast, all naïve ferrets developed acute infection following assisted and direct exposure to oronasal fluid from animals that were shedding either NiV-BD or NiV-MY.In contrast, active transfer of infected bodily fluids consistently results in transmission, regardless of the virus strain.These observations suggest that the risk of NiV transmission is underpinned by social and environmental factors, and will have practical implications for managing transmission risk during outbreaks of human disease.

View Article: PubMed Central - PubMed

Affiliation: Health and Biosecurity, Australian Animal Health Laboratory, Commonwealth Scientific and Industrial Research Organisation, Geelong, Victoria, Australia.

ABSTRACT
Person-to-person transmission is a key feature of human Nipah virus outbreaks in Bangladesh. In contrast, in an outbreak of Nipah virus in Malaysia, people acquired infections from pigs. It is not known whether this important epidemiological difference is driven primarily by differences between NiV Bangladesh (NiV-BD) and Malaysia (NiV-MY) at a virus level, or by environmental or host factors. In a time course study, ferrets were oronasally exposed to equivalent doses of NiV-BD or NiV-MY. More rapid onset of productive infection and higher levels of virus replication in respiratory tract tissues were seen for NiV-BD compared to NiV-MY, corroborating our previous report of increased oral shedding of NiV-BD in ferrets and suggesting a contributory mechanism for increased NiV-BD transmission between people compared to NiV-MY. However, we recognize that transmission occurs within a social and environmental framework that may have an important and differentiating role in NiV transmission rates. With this in mind, ferret-to-ferret transmission of NiV-BD and NiV-MY was assessed under differing viral exposure conditions. Transmission was not identified for either virus when naïve ferrets were cohoused with experimentally-infected animals. In contrast, all naïve ferrets developed acute infection following assisted and direct exposure to oronasal fluid from animals that were shedding either NiV-BD or NiV-MY. Our findings for ferrets indicate that, although NiV-BD may be shed at higher levels than NiV-MY, transmission risk may be equivalently low under exposure conditions provided by cohabitation alone. In contrast, active transfer of infected bodily fluids consistently results in transmission, regardless of the virus strain. These observations suggest that the risk of NiV transmission is underpinned by social and environmental factors, and will have practical implications for managing transmission risk during outbreaks of human disease.

No MeSH data available.


Related in: MedlinePlus