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Geology topics

P. E. McAllister

Publications and source records attributed to P. E. McAllister.

At least 19 recordsLinked to original sources
USGS2006

A lymphosarcoma of thymic origin in the rainbow trout, Salmo gairdneri Richardson

A rainbow trout with a malignant lymphoma of probable thymic origin showed direct spread of the tumour to the gills, metastases to the liver and head kidney, and the presence of abnormal circulating lymphocytes. The cells of the tumour possessed plasma membrane immunoglobulin detectable by immuno–fluorescence. Examination of the tumour cells by transmission electron microscopy revealed no evidence of virus associated with the cells. Infectious viruses could not be detected in the tumour tissue, and the tumour was not transmissible by injection of live tumour cells into young rainbow trout. Attempts to establish the tumour in long–term culture were unsuccessful.

Journal of Fish Diseases↗
USGS2006

Mycoplasma contamination in fish cell lines: An evaluation of detection by differential incorporation of 3H-uridine and 14C-uracil

Differential incorporation of uridine and uracil was used to assay for mycoplasma contamination in five fish cell lines: bluegill fry (BF-2), chinook salmon embryo (CHSE-214), epithelioma papillosum cyprini (EPC), fathead minnow (FHM) and rainbow trout gonad (RTG-2). The method was not suitable for monitoring BF-2, CHSE-214, FHM, and RTG-2 cell lines because they incorporated uracil. Differential incorporation of uridine and uracil may be applicable for screening EPC cells because only this cell line could distinguish cultures experimentally infected with Mycoplasma orale from cultures known to be free from microbial contaminants.

Journal of Fish Diseases↗
USGS2005

Development of a subunit vaccine for infectious pancreatic necrosis virus using a baculovirus insect/larvae system

Various attempts to develop a vaccine against infectious pancreatic necrosis virus (IPNV) have not yielded consistent results. Thus, at present, no commercial vaccine is available that can be used with confidence to immunize fry of salmon and trout. We generated a cDNA clone of the large genome segment A of an IPNV Sp strain and expressed all structural protein genes in insect cells and larvae using a baculovirus expression system. Green fluorescent protein was also co-expressed as a reporter molecule. High yields of IPNV proteins were obtained and the structural proteins self assembled to form virus-like particles (VLPs). We tested the immunogenicity of the putative VLP antigen in immersion vaccine experiments (two concentrations) in rainbow trout (Oncorhynchus mykiss) fry, and by intraperitoneal immunisation of Atlantic salmon (Salmo salar) pre-smolts using an oil adjuvant formulation. Rainbow trout were challenged by immersion using either the Sp or the VR-299 strain of IPNV two or three weeks post-vaccination, while Atlantic salmon were bath challenged with Sp strain after two months, after parr-smolt transformation. In the rainbow trout fry challenged two weeks post-immunization, cumulative mortality rates three weeks post challenge were 14 % in the fry that had received the highest dose versus 8 % in the control groups. No indication of protection was seen in repeated trials using a lower dose of antigen and challenge three weeks post-immunisation. The cumulative mortality rate of intraperitoneally immunised Atlantic salmon post-smolts four weeks post challenge was lower (56 %) than in the control fish (77 %), showing a dose-response pattern.

Conference Paper↗
USGS2000

Experimental infectious pancreatic necrosis infections: propagative or point-source epidemic?

Experimentally initiated epidemics of infectious pancreatic necrosis in rainbow-trout fry were analyzed using a modification of the standard mathematical model for a simple propagative epidemic. Contrary to expectations, the value of the transmission parameter ( β ) was inversely related to initial density of susceptible hosts. This anomaly can be explained if we assume that the experimental epidemics were point-source rather than propagative epidemics. The implications of this conclusion for modeling experimental and natural epidemics are discussed.

Preventive Veterinary Medicine↗
USGS2000

Susceptibility of Arctic char to experimental challenge with Infectious Hematopoietic Necrosis Virus (IHNV) and Infectious Pancreatic Necrosis Virus (IPNV)

Arctic char Salvelinus alpinus were exposed to the fish pathogens infectious hematopoietic necrosis virus (IHNV) and infectious pancreatic necrosis virus (IPNV) to estimate susceptibility of the species to infection. Fish were immersion challenged at 46, 74, and 95 d posthatch for 5 h in viral concentration of 10 3 or 10 5 PFU(plaque-forming units)/mL and were monitored for 21 d postchallenge. Fish that died were assayed individually for virus-associated mortality, and survivors were assayed individually to estimate prevalence of virus carrier status. Arctic char succumbed to IHNV infection with population losses as high as 41%, and prevalence of IHNV carriers in surviving fish was 24% or less with virus titers in carrier fish ranging from 2.5 × 10 2 PFU/g to greater than 1.3 × 10 6 PFU/g. Infections with IPNV resulted in losses of 20% or less, and prevalence of IPNV carriers in surviving fish was as high as 82% with virus titers in carrier fish ranging from 2.5 × 10 2 PFU/g to greater than 5.0 × 10 6 PFU/g. Logistic regression models were developed for the mortality and infection data for each virus. For IHNV, the odds of dying or becoming infected were significantly greater for the fish from the 74-d age-group than for the fish from the 46-d or 95-d age-groups. Fish exposed to 10 5 PFU of IHNV/mL had significantly greater odds of dying or becoming infected than fish exposed to 10 3 PFU/mL. For IPNV, the odds of dying were significantly greater for the 74-d age-group compared with the other two age-groups. The 74-d fish were also significantly more likely to become infected than the 95-d-old fish. Fish exposed to 10 5 PFU of IPNV/mL had significantly greater odds of dying or becoming infected than fish exposed to 10 3 PFU of IPNV /mL.

Journal of Aquatic Animal Health↗
USGS1998

Infectious pancreatic necrosis virus: transmission from infectious to susceptible rainbow trout fry

Fry of rainbow trout Oncorhynchus mykiss were exposed to serotype VR-299 of infectious pancreatic necrosis virus (IPNV) by using a standardized immersion challenge. In concurrent experiments, fish were monitored for 11 d for excretion of IPNV or monitored for 9 d for excretion and transmission of IPNV to susceptible rainbow trout fry. Immersion-challenged fish began excreting virus within 2 d after challenge. The rate of IPNV excretion per fish increased steadily from about day 4 to day 8 and then decreased. Virus concentrations in tissues of immersion-challenged fish increased exponentially. Susceptible fish became infected with IPNV within 4 d after being introduced to immersion-challenged fish (e.g., 2 d after the challenged fish began excreting virus). By 9 d, 84% of the susceptible fish were infected with IPNV.

Journal of Aquatic Animal Health↗
USGS1995

Detection and identification of aquatic birnaviruses by PCR assay

A reverse transcriptase polymerase chain reaction (RT-PCR) assay was developed for the detection and identification of aquatic birnaviruses. The four sets of primers (PrA, PrB, PrC, and PrD) that we used are specific for regions of cDNA coded by genome segment A of aquatic birnaviruses. PrA identifies a large fragment (1,180 bp) within the pVP2-coding region, and PrB identifies a 524-bp fragment within the sequence amplified by PrA. Primer set PrC frames a genome fragment (339 bp) within the NS-VP3-coding region, and PrD identifies a 174-bp sequence within the fragment identified by PrC. PrB and PrD amplified cDNAs from all nine recognized serotypes of aquatic birnavirus serogroup A as well as the N1 isolate that may represent a 10th serotype. These results indicate that these three primer sequences are highly conserved and can be used in PCR assays for group identification of these viruses. PrA routinely produced amplification products from eight serotypes but exhibited variable results with one serotype, and primer PrC identified 6 of the 11 virus isolates tested. The qualitative sensitivity of the RT-PCR assay was evaluated by comparison of the results with those of cell culture isolation assays. With the exception of one sample, the RT-PCR assay with primer PrD was as accurate as cell culture isolation for detecting virus in kidney and spleen tissues from naturally infected, asymptomatic carrier fish. These results indicate that the RT-PCR assay can be a rapid and reliable substitute for cell culture methods for the detection of aquatic birnaviruses.

Journal of Clinical Microbiology↗
USGS1994

Effects of elevated water temperature and immunosuppressant treatment on prevalence and titer of infectious pancreatic necrosis virus in naturally infected brook trout

Using fingerlings of brook trout Salvelinus fontinalis naturally infected with infectious pancreatic necrosis virus (IPNV), we demonstrated that elevated water temperature and treatment with the immunosuppressant triamcinolone acetonide (generic Kenalog®) significantly increases the titer of IPNV and probably also the prevalence of the infection. Stress-promoting treatments could potentially enhance the capability to detect various fish viral agents.

Journal of Aquatic Animal Health↗