Geology topics

Katja Einer-Jensen

Publications and source records attributed to Katja Einer-Jensen.

4 recordsLinked to original sources

USGS2017

Influence of temperature on the efficacy of homologous and heterologous DNA vaccines against viral hemorrhagic septicemia in Pacific Herring

Homologous and heterologous (genogroup Ia) DNA vaccines against viral hemorrhagic septicemia virus (genogroup IVa) conferred partial protection in Pacific Herring Clupea pallasii . Early protection at 2 weeks postvaccination (PV) was low and occurred only at an elevated temperature (12.6°C, 189 degree days), where the relative percent survival following viral exposure was similar for the two vaccines (IVa and Ia) and higher than that of negative controls at the same temperature. Late protection at 10 weeks PV was induced by both vaccines but was higher with the homologous vaccine at both 9.0°C and 12.6°C. Virus neutralization titers were detected among 55% of all vaccinated fish at 10 weeks PV. The results suggest that the immune response profile triggered by DNA vaccination of herring was similar to that reported for Rainbow Trout Oncorhynchus mykiss by Lorenzen and LaPatra in 2005, who found interferon responses in the early days PV and the transition to adaptive response later. However, the protective effect was far less prominent in herring, possibly reflecting different physiologies or adaptations of the two fish species.

Journal of Aquatic Animal Health↗

USGS2005

Genotyping of the fish rhabdovirus, viral haemorrhagic septicaemia virus, by restriction fragment length polymorphisms

The aim of this study was to develop a standardized molecular assay that used limited resources and equipment for routine genotyping of isolates of the fish rhabdovirus, viral haemorrhagic septicaemia virus (VHSV). Computer generated restriction maps, based on 62 unique full-length (1524 nt) sequences of the VHSV glycoprotein ( G ) gene, were used to predict restriction fragment length polymorphism (RFLP) patterns that were subsequently grouped and compared with a phylogenetic analysis of the G -gene sequences of the same set of isolates. Digestion of PCR amplicons from the full-length G -gene by a set of three restriction enzymes was predicted to accurately enable the assignment of the VHSV isolates into the four major genotypes discovered to date. Further sub-typing of the isolates into the recently described sub-lineages of genotype I was possible by applying three additional enzymes. Experimental evaluation of the method consisted of three steps: (i) RT-PCR amplification of the G -gene of VHSV isolates using purified viral RNA as template, (ii) digestion of the PCR products with a panel of restriction endonucleases and (iii) interpretation of the resulting RFLP profiles. The RFLP analysis was shown to approximate the level of genetic discrimination obtained by other, more labour-intensive, molecular techniques such as the ribonuclease protection assay or sequence analysis. In addition, 37 previously uncharacterised isolates from diverse sources were assigned to specific genotypes. While the assay was able to distinguish between marine and continental isolates of VHSV, the differences did not correlate with the pathogenicity of the isolates.

Veterinary Microbiology↗

USGS2003

Phylogeography of infectious haematopoietic necrosis virus in North America

Infectious hematopoietic necrosis virus (IHNV) is a rhabdoviral pathogen that infects wild and cultured salmonid fish throughout the Pacific Northwest of North America. IHNV causes severe epidemics in young fish and can cause disease or occur asymptomatically in adults. In a broad survey of 323 IHNV field isolates, sequence analysis of a 303 nucleotide variable region within the glycoprotein gene revealed a maximum nucleotide diversity of 8·6 %, indicating low genetic diversity overall for this virus. Phylogenetic analysis revealed three major virus genogroups, designated U, M and L, which varied in topography and geographical range. Intragenogroup genetic diversity measures indicated that the M genogroup had three- to fourfold more diversity than the other genogroups and suggested relatively rapid evolution of the M genogroup and stasis within the U genogroup. We speculate that factors influencing IHNV evolution may have included ocean migration ranges of their salmonid host populations and anthropogenic effects associated with fish culture.

Journal of General Virology↗

USGS2002

Molecular diagnosis of infectious hematopoietic necrosis and viral hemorrhagic septicemia

The fish rhabdoviruses, infectious hematopoietic necrosis virus (IHNV) and viral hemorrhagic septicemia virus (VHSV), cause extensive losses among salmon and trout in several areas of the world (Bootland and Leong, 1999; Smail, 1999; Wolf, 1988). Historically, IHNV was endemic among wild anadromous salmonids in the western portion of North America, but the virus has spread to stocks of cultured rainbow trout ( Oncorhynchus mykiss ) in the United States, Asia and Western Europe, probably as a result of the movement of infected fish or eggs (Winton, 1991). Prior to 1989, VHSV was thought to be largely restricted to freshwater fishes in Western Europe (Wolf, 1988); however, in the last decade, VHSV has been isolated from an increasing number of free-living marine fish species in the North Pacific and North Atlantic Oceans (Dixon et al ., 1997; Dixon, 1999; Kent et al ., 1998; Meyers and Winton, 1995; Meyers et al ., 1999; Mortensen et al ., 1999; Smail; 2000, Takano et al ., 2000). These findings have lead to the conclusion that both viruses are principally endemic among marine or anadromous fish species, but have established themselves in freshwater among cultured salmonids where their effects are most frequently observed.

Book chapter↗