Papers by Douglas A Gregg
Journal of Veterinary Diagnostic Investigation, 1995
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PubMed, Dec 9, 1989
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PubMed, 1980
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American Journal of Veterinary Research, May 1, 1986
The association of African swine fever virus (ASFV) with swine erythrocytes in vivo, in high tite... more The association of African swine fever virus (ASFV) with swine erythrocytes in vivo, in high titers, was verified by inoculating 30 pigs with 17 ASFV isolates and assaying their plasma and washed erythrocyte fractions for residual virus. Viral antigens were specifically localized on the surface of in vitro and in vivo swine erythrocytes, using the fluorescent antibody technique and 3 monoclonal antibodies specific for ASFV. The same monoclonal antibodies immunoprecipitated virus-specific polypeptides of molecular weights 13 kd and 73 kd from ASFV-infected Vero cells. Erythrocytes from viremic swine infected with Lisbon-60, Dominican Republic, Badajoz-M98, or Cameroon isolates of ASFV were studied by transmission electron microscopy. Virus was found in membrane depressions at the surface of erythrocytes. These surface depressions resembled stages of smooth surfaced pits. Erythrocytes from viremic pigs were fragile osmotically.
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Revue Scientifique Et Technique De L Office International Des Epizooties, Jun 1, 1991
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Springer eBooks, 1991
ABSTRACT African swine fever (ASF) presently occurs in domestic pigs as a virulent disease, and a... more ABSTRACT African swine fever (ASF) presently occurs in domestic pigs as a virulent disease, and a moderately virulent disease. The virulent form causes a necrotizing disease and high mortality in 7 to 10 days with negligible immunoglobulin production. The moderately virulent disease does not produce extensive necrosis, has low mortality, and detectable antibody to ASF is produced starting at 6 days post-inoculation (DPI). Using avidin-biotin alkaline phosphatase (ABC-AP) immunostaining systems on paraffin sections we have identified ASF-infected interdigitating dendritic cells (IDCs) in the lymph node as early as 2 days post-infection. Infection of interdigitating cells was confirmed with anti-S-100 double staining and by finding viral factories in these cells by electron microscopy. Similar electron microscopic results were obtained in vitro with Langerhan’s cells (LCs) collected from skin expiant cultures. The infection and necrosis of these antigen-presenting cells may explain the lack of a humoral immune response in virulent ASF, despite their apparently normal lymphocyte functions.
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Journal of Veterinary Diagnostic Investigation, 1995
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Journal of Veterinary Diagnostic Investigation, 1995
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Journal of Veterinary Diagnostic Investigation, 1995
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Vaccine, Dec 30, 2005
Recent outbreaks of foot-and-mouth disease virus (FMDV) demonstrate that this highly contagious v... more Recent outbreaks of foot-and-mouth disease virus (FMDV) demonstrate that this highly contagious viral infection of cloven hoofed animals continues to be a significant economic problem worldwide. Debate about the most effective way to respond to outbreaks of FMDV in disease free countries continues to center on the use of vaccines. In this report, we present data showing that a commercially available, standard dose vaccine formulation can fully protect cattle against direct challenge with the virus in as little as 7 days with no carrier transmission to naïve animals. Cattle challenged 4 days after vaccination have reduced disease severity, no detectable virus in blood and little virus shedding from nasal secretions. These significant effects at 4 days post vaccination, confirmed in two separate trials, support the value of using currently available vaccines as a first line of defense against foot-and-mouth disease (FMD) outbreaks.
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Journal of Swine Health and Production, 2002
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Vaccine, 2012
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Annals of the New York Academy of Sciences, Jun 1, 1983
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CRC Press, Dec 6, 2017
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Abstract. Three llamas (Lama glama) were experimentally infected intranasally with an isolate of ... more Abstract. Three llamas (Lama glama) were experimentally infected intranasally with an isolate of equine herpesvirus-1 (EHV-1) from the brain of an alpaca that had experienced severe neurologic signs. Two of the 3 llamas developed severe neurologic disorders following inoculation; 1 died, and 1 was euthanized in a moribund state. The third llama showed only mild neurologic signs. The euthanized llama had preexisting antibodies to-EHV-1, and the remaining 2 llamas were seronegative (virus neutralization titer < 6) at the time of inoculation. One of the seronegative llamas died acutely without production of detectable antibodies, and the other developed antibodies typical of a primary immune response. The EHV-1 virus was recovered only from a sample of the thalamus of the llama that died acutely. Histopathologic lesions were observed in the brain and retina of the dead and euthanized animals. This study verifies the pathogenic potential of EHV-1 for llamas. Equine herpesvirus-1 (EHV...
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Southwestern Entomologist
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Http Dx Doi Org 10 2460 Javma 2003 223 1151, Dec 27, 2005
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Skin Langerhans (Dendritic) Cells in Virus Infections and AIDS, 1991
ABSTRACT African swine fever (ASF) presently occurs in domestic pigs as a virulent disease, and a... more ABSTRACT African swine fever (ASF) presently occurs in domestic pigs as a virulent disease, and a moderately virulent disease. The virulent form causes a necrotizing disease and high mortality in 7 to 10 days with negligible immunoglobulin production. The moderately virulent disease does not produce extensive necrosis, has low mortality, and detectable antibody to ASF is produced starting at 6 days post-inoculation (DPI). Using avidin-biotin alkaline phosphatase (ABC-AP) immunostaining systems on paraffin sections we have identified ASF-infected interdigitating dendritic cells (IDCs) in the lymph node as early as 2 days post-infection. Infection of interdigitating cells was confirmed with anti-S-100 double staining and by finding viral factories in these cells by electron microscopy. Similar electron microscopic results were obtained in vitro with Langerhan’s cells (LCs) collected from skin expiant cultures. The infection and necrosis of these antigen-presenting cells may explain the lack of a humoral immune response in virulent ASF, despite their apparently normal lymphocyte functions.
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Viral Immunol, 2008
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Papers by Douglas A Gregg