| 1. |
- Wallensten, Anders, et al.
(författare)
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Surveillance of influenza A virus in migratory waterfowl in northern Europe
- 2007
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Ingår i: Emerging Infectious Diseases. - 1080-6040 .- 1080-6059. - 1080-6040 ; 13:3, s. 404-411
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Tidskriftsartikel (refereegranskat)abstract
- We conducted large-scale, systematic sampling of influenza type A virus in migratory waterfowl (mostly mallards [Anas platyrhynchos]) at Ottenby Bird Observatory, southeast Sweden. As with previous studies, we found a higher prevalence in fall than spring, and among juveniles compared with adults. However, in contrast to other studies, we found that prevalence in spring was sometimes high (mean 4.0%, highest 9.5%). This finding raises the possibility that ducks are capable of perpetuating influenza A virus of different subtypes and subtype combinations throughout the year and from 1 year to the next. Isolation of the H5 and H7 subtypes was common, which suggests risk for transmission to sensitive domestic animals such as poultry. We argue that wild bird screening can function as a sentinel system, and we give an example of how it could have been used to forecast a remote and deadly outbreak of influenza A in poultry.
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| 2. |
- Karlsson, Malin, et al.
(författare)
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A real-time PCR assay for the monitoring of influenza a virus in wild birds
- 2007
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Ingår i: Journal of Virological Methods. - : Elsevier BV. - 0166-0934 .- 1879-0984. ; 144:1-2, s. 27-31
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Tidskriftsartikel (refereegranskat)abstract
- A screening system including a new real-time PCR assay for the monitoring of influenza A virus in wild birds was developed. The real-time PCR assay uses SYBR green chemistry and the primers are targeting the matrix gene of influenza A virus. The performance of the assay was compared with two other assays, one assay also using SYBR green chemistry and one assay using TaqMan chemistry, i.e. a specific probe. A total of 45 fecal bird samples were analysed for influenza A virus in three different PCR reactions. Overall, 26 samples were positive in at least one of the three real-time PCR assays. Of the 26 samples, 18 were positive by all three reactions. Eight samples were found positive exclusively by the two SYBR green reactions, six of which were detected by both SYBR green reactions. Of the 26 positive samples, 15 samples were verified as positive either by virus isolation or influenza A M2-gene PCR. The results showed that the two SYBR green systems had a higher performance regarding the detection of influenza A as compared to the PCR reaction using a specific probe.
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| 3. |
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| 4. |
- Voutilainen, Liina, et al.
(författare)
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Life-long shedding of Puumala hantavirus in wild bank voles (Myodes glareolus)
- 2015
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Ingår i: Journal of General Virology. - : Society for General Microbiology. - 0022-1317 .- 1465-2099. ; 96:6, s. 1238-1247
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Tidskriftsartikel (refereegranskat)abstract
- The knowledge of viral shedding patterns and viraemia in the reservoir host species is a key factorin assessing the human risk of zoonotic viruses. The shedding of hantaviruses (familyBunyaviridae) by their host rodents has widely been studied experimentally, but rarely in naturalsettings. Here we present the dynamics of Puumala hantavirus (PUUV) shedding and viraemia innaturally infected wild bank voles (Myodes glareolus). In a monthly capture–mark–recapturestudy, we analysed 18 bank voles for the presence and relative quantity of PUUV RNA in theexcreta and blood from 2 months before up to 8 months after seroconversion. The proportion ofanimals shedding PUUV RNA in saliva, urine and faeces peaked during the first month afterseroconversion, but continued throughout the study period with only a slight decline. The quantityof shed PUUV in reverse transcription quantitative PCR (RT-qPCR) positive excreta was constantover time. In blood, PUUV RNA was present for up to 7 months but both the probability of viraemiaand the virus load declined with time. Our findings contradict the current view of a decline in virusshedding after the acute phase and a short viraemic period in hantavirus infection – anassumption widely adopted in current epidemiological models. We suggest the life-long sheddingas a means of hantaviruses to survive over host population bottlenecks, and to disperse infragmented habitats where local host and/or virus populations face temporary extinctions. Ourresults indicate that the kinetics of pathogens in wild hosts may differ considerably from thoseobserved in laboratory settings.
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| 5. |
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| 6. |
- Wallerström, Sofie, et al.
(författare)
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Detection of antibodies against H5 and H7 strains in birds : evaluation of influenza pseudovirus particle neutralization tests
- 2014
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Ingår i: Infection Ecology & Epidemiology. - : Informa UK Limited. - 2000-8686 .- 2000-8686. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Avian influenza viruses circulate in bird populations, and it is important to maintain and uphold our knowledge of the viral strains that are currently of interest in this context. Here, we describe the use of hemagglutinin-pseudotype retroviruses based on highly pathogenic influenza viruses for the screening of avian sera for influenza A antibodies. Our aim was also to determine whether the pseudovirus neutralization tests that we assessed were sensitive and simple to use compared to the traditional methods, including hemagglutination inhibition assays and microneutralization tests.MATERIAL AND METHODS: H5 and H7 pseudovirus neutralization tests were evaluated by using serum from infected rabbits. Subsequently, the assays were further investigated using a panel of serum samples from avian species. The panel contained samples that were seropositive for five different hemagglutinin subtypes as well as influenza A seronegative samples.RESULTS AND DISCUSSION: The results suggest that the pseudovirus neutralization test is an alternative to hemagglutination inhibition assays, as we observed comparable titers to those of both standard microneutralizations assays as well as hemagglutinin inhibition assays. When evaluated by a panel of avian sera, the method also showed its capability to recognize antibodies directed toward low-pathogenic H5 and H7. Hence, we conclude that it is possible to use pseudoviruses based on highly pathogenic avian influenza viruses to screen avian sera for antibodies directed against influenza A subtypes H5 and H7.
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