Transgenic resistance to PMTV and PVA provides novel insights to viral long-distance movement

The studies in this thesis describe forms of transgenic resistance to plant viruses and how they can be used for studying viral infection cycle. S. tuberosum cv. Saturna expressing the CP gene of Potato mop-top virus (PMTV) was grown in a field infested with the viruliferous vector of PMTV, S. subterranea. The incidence of PMTV-infected tubers was lower in the CP-transgenic potato than in non-transgenic potato. RNA dot-blot analysis revealed that in tubers infected with PMTV, all three RNAs were present. N. benthamiana plants expressing the CP gene of PMTV were inoculated by two different methods i) mechanical inoculation to leaves and ii) growing plants in soil infested with viruliferous S. subterranea. Results showed that the expression of the transgene-derived RNA (or CP) inhibits replication of homologous RNA 2 in transgenic N. benthamiana. Furthermore, the results showed that transgene-mediated resistance to PMTV differs in roots and leaves. Mechanical inoculation with PMTV on CP-transgenic N. benthamiana resulted in symptomless, systemic movement of RNA 1 and RNA 3, but not the CP-encoding RNA (RNA 2). These findings show that PMTV RNA 1 and RNA 3 can infect and move systemically in N. benthamiana without the CP and RNA 2. N. benthamiana transformed with the P1 and VPg cistron, respectively, of Potato virus A (PVA) displayed: i) resistance to PVA infection, ii) susceptibility, or iii) systemic infection followed by recovery from PVA infection of new leaves. Long-distance transport of PVA from lower, infected parts of recovered plants was compromised in the recovered tissue. This result suggests that PVA is moving as ribonucleoprotein complex other than virus particles. N. benthamiana transformed with a polycistronic transgene encoding the CI-NIa-CP cistrons of PVA was susceptible to PVA infection. VPg (the N-proximal part of NIa) is a well-known virulence factor of potyviruses and its possible role in suppression of RNA silencing was studied. PVA VPg was found to increase the severity of disease symptoms when expressed from a Potato virus X vector in N. benthamiana. However, PVA VPg did not show apparent RNA silencing suppression activity. The reason why the polycistronic transgene did not provide resistance could not be resolved

Från Sverige till Rosengård - Studie av en etniskt diversifierad marknad

Studiens syfte är att undersöka om, och i sådana fall hur, företag anpassar sina marknadsföringsinstrument på en lokalt etniskt diversifierad marknad. Vidare ämnas studera om företag, på central nivå, tillvaratar lokala butikers/kontors erfarenheter och kunskaper av en etniskt diversifierad marknad. En kvalitativ metod valdes eftersom vi ämnade skapa en djupgående förståelse och helhetsuppfattning av den undersöka företeelsen. Djupintervjuer genomfördes med företagsrepresentanter från fallföretagen samt med experter på den studerande företeelsen. Dessa intervjuer utgjorde empirin som sedan var grunden för analysen och slutsatserna. Hos samtliga fallföretag hade någon form av anpassning av marknadsföringsinstrumenten skett till den etniskt diversifierade marknaden. Produkt, promotion och personal är de marknadsföringsinstrument med vilka fallföretagen anpassat sig till den lokala etniskt diversifierade marknaden. Tillvaratagandet av personalens kunskap från kontor/butiker verksamma på en etniskt diversifierad marknad varierade mellan fallföretagen, från att inte vara intresserade till försök till tillvaratagande. Inget av fallföretagen hade ett utvecklat systematiskt tillvaratagande, utan i de fall tillvaratagande önskades skedde det på ett ostrukturerat sätt. Företag som på centralnivå arbetar med mångfaldsfrågor tycktes vara mera intresserade av att tillvarata kunskapen som skapats på en lokalt etniskt diversifierad marknad

Prevalence and subtypes of Influenza A Viruses in Wild Waterfowl in Norway 2006-2007

The prevalence of influenza A virus infection, and the distribution of different subtypes of the virus, were studied in 1529 ducks and 1213 gulls shot during ordinary hunting from August to December in two consecutive years, 2006 and 2007, in Norway. The study was based on molecular screening of cloacal and tracheal swabs, using a pan-influenza A RT-PCR. Samples found to be positive for influenza A virus were screened for the H5 subtype, using a H5 specific RT-PCR, and, if negative, further subtyped by a RT-PCR for the 3'-part of the hemagglutinin (HA) gene, encompassing almost the entire HA2, and the full-length of the neuraminidase (NA) gene, followed by sequencing and characterization. The highest prevalence (12.8%) of infection was found in dabbling ducks (Eurasian Wigeon, Common Teal and Mallard). Diving ducks (Common Goldeneye, Common Merganser, Red-breasted Merganser, Common Scoter, Common Eider and Tufted Duck) showed a lower prevalence (4.1%). In gulls (Common Gull, Herring Gull, Black-headed Gull, Lesser Black-headed Gull, Great Black-backed Gull and Kittiwake) the prevalence of influenza A virus was 6.1%. The infection prevalence peaked during October for ducks, and October/November for gulls. From the 16 hemagglutinin subtypes known to infect wild birds, 13 were detected in this study. Low pathogenic H5 was found in 17 dabbling ducks and one gull

Virological and serological surveillance for type A influenza in the black-legged kittiwake (Rissa tridactyla)

<p>Abstract</p> <p>Background</p> <p>The epidemiology of avian influenza viruses (AIVs) in gulls is only partially known. The role of the world's most numerous gull species, the black-legged kittiwake (<it>Rissa tridactyla</it>), as a potential AIV reservoir species has been unclear. The prevalence of AIV and humoral response against AIV were therefore studied in a colony of apparently healthy black-legged kittiwakes breeding in a nesting cliff in the South West Barents Region of Norway (70°22' N, 31°10' E), in 2008 and 2009.</p> <p>Results</p> <p>AIVs were detected from the oropharynx and cloaca in low amounts, with prevalences of 15% and 5%, in 2008 and 2009, respectively. Direct, partial sequencing of the hemagglutinin (HA) gene revealed that the H4 subtype was present. In 2009, antibodies to influenza A virus were detected in sera from 57 of 80 adult birds. In contrast, none of the three-week-old chicks (n = 18) tested seropositive. Hemagglutination inhibition (HI) assays demonstrated that the adult kittiwakes primarily had antibodies specific to the gull-associated H13 and H16 subtypes, with antibodies to H16 being most common.</p> <p>Conclusions</p> <p>These results support that the highly pelagic black-legged kittiwake is a reservoir of AIV. The serological findings suggest that H16 might be the main AIV subtype in the black-legged kittiwake. Further studies are needed to understand the ecology of AIV in the black-legged kittiwake and in gulls in general.</p