| 1. |
- Wallenhammar, Amélie, 1986-, et al.
(författare)
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Developing a novel strategy to determine new Tick-borne encephalitis foci
- 2018
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Ingår i: 15th Smögen Summer Symposium on Virology, Smögen, Sweden, August 23-25, 2018..
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Konferensbidrag (refereegranskat)abstract
- TBEV is the most important viral tick-borne zoonosis in Europe, and infection may lead to severeCNS disease, including encephalitis and myelitis. Climate changes have increased the tickdistribution in Sweden, increasing the risk areas of Tick-borne encephalitis (TBE) at severalregions including the Örebro county. The TBE virus (TBEV) is usually transmitted to humans viatick bites, however oral transmission through consumption of non-pasteurized dairy products havealso been described. Both TBEV and antibodies against the viral proteins have been detected inmilk of goats, sheep and cattle. Since the prevalence of TBEV in the tick population is low there is a need for new and robust surveillance techniques identifying novel risk areas of TBEV at earlystages.In this study we have developed a strategy for identifying new TBEV foci. We have collected raw milk and colostrum samples from sheep and goats in the Örebro region. The milk samples were analyzed for the presence of TBEV antibodies by ELISA. In addition, the ELISA results were further verified by an in-house Western Blot assay where milk samples were used asprimary antibody to detect the Envelope-protein of TBEV. This method has so far revealed two novel TBEV foci within the Örebro county. Questing ticks and ticks feeding on sheep have been collected at areas of TBEV positive milk. The ticks are currently being analyzed for TBEV by PCR. The specific Örebro strains will be isolated from TBEV positive ticks and the viral genomeswill be further characterized using established next-generation sequencing technique.
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| 2. |
- Wallenhammar, Amélie, 1986-, et al.
(författare)
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Revealing new tick-borne encephalitis foci by screening antibodies in sheep milk
- 2019
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Ingår i: 16th Smögen Symposium on Virology, August 22-24, 2019.
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Konferensbidrag (refereegranskat)abstract
- Climate changes have increased the tick-distribution in Sweden, and the prevalence of ticks has been predicted to increase towards the northern parts of the country, increasing the risk of tick-borne zoonosis in new regions. Tick-borne encephalitis (TBE) is the most important viral tick-borne zoonosis in Sweden as well as in Europe. TBE virus (TBEV) infection often leads to severe CNS disease, including encephalitis and severe myelitis, which may lead to paralysis and respiratory failure in humans. TBEV and antibodies against TBEV are excreted in milk of goats, sheep and cattle and the virus can be ingested orally by consumption of non-pasteurized dairy products. Since the prevalence of TBEV in the tick population is low there is a need for new and robust surveillance techniques identifying new risk areas of TBEV at early stages.In this study we have developed a novel strategy for identifying new TBEV foci. We have collected raw milk and colostrum samples from sheep and goats in Örebro County, Sweden. The milk samples were analyzed for the presence of TBEV antibodies by ELISA, and validated by an in-house Western Blot assay where milk samples were used as primary antibody to detect purified TBEV E-protein. By monitoring TBEV antibodies in milk we have found three novel foci in the Örebro County which also overlap with the plausible place of infection of registered human TBE cases reported during 2009-2018. Furthermore, the stability of TBEV in milk and raw milk was studied at different temperatures. Our data indicates that keeping unpasteurized milk at 4 ˚C will preserve the infectivity of TBEV for several days. Ticks have also been collected from areas with TBEV positive milk. We aim to extract total RNA from the sampled ticks, followed by TBEV detection by nested-PCR and next-generation sequencing.Here we present a novel technique to reveal risk areas of TBE in Sweden, which is robust, reliable, and non-invasive and can accordingly be used to map TBEV “hotspots”. In the TBE foci, more than 50 % of the tested animals were antibody positive, and TBEV infectivity in refrigerated milk was preserved, stressing the importance of pasteurization before consumption.
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| 3. |
- Wallenhammar, Amélie, 1986-, et al.
(författare)
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Revealing new tick-borne encephalitis virus foci by screening antibodies in sheep milk
- 2020
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Ingår i: Parasites & Vectors. - : BioMed Central. - 1756-3305. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Tick distribution in Sweden has increased in recent years, with the prevalence of ticks predicted to spread towards the northern parts of the country, thus increasing the risk of tick-borne zoonoses in new regions. Tick-borne encephalitis (TBE) is the most significant viral tick-borne zoonotic disease in Europe. The disease is caused by TBE virus (TBEV) infection which often leads to severe encephalitis and myelitis in humans. TBEV is usually transmitted to humans via tick bites; however, the virus can also be excreted in the milk of goats, sheep and cattle and infection may then occur via consumption of unpasteurised dairy products. Virus prevalence in questing ticks is an unreliable indicator of TBE infection risk as viral RNA is rarely detected even in large sample sizes collected at TBE-endemic areas. Hence, there is a need for robust surveillance techniques to identify emerging TBEV risk areas at early stages.METHODS: Milk and colostrum samples were collected from sheep and goats in Örebro County, Sweden. The milk samples were analysed for the presence of TBEV antibodies by ELISA and validated by western blot in which milk samples were used to detect over-expressed TBEV E-protein in crude cell extracts. Neutralising titers were determined by focus reduction neutralisation test (FRNT). The stability of TBEV in milk and colostrum was studied at different temperatures.RESULTS: In this study we have developed a novel strategy to identify new TBEV foci. By monitoring TBEV antibodies in milk, we have identified three previously unknown foci in Örebro County which also overlap with areas of TBE infection reported during 2009-2018. In addition, our data indicates that keeping unpasteurised milk at 4 °C will preserve the infectivity of TBEV for several days.CONCLUSIONS: Altogether, we report a non-invasive surveillance technique for revealing risk areas for TBE in Sweden, by detecting TBEV antibodies in sheep milk. This approach is robust and reliable and can accordingly be used to map TBEV "hotspots". TBEV infectivity in refrigerated milk was preserved, emphasising the importance of pasteurisation (i.e. 72 °C for 15 s) prior to consumption.
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