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Biomedical subjects

D A Halvorson

Publications and source records attributed to D A Halvorson.

At least 37 records · Page 2Linked to original sources
PubMed1994

A type-specific avian influenza virus subunit vaccine for turkeys: induction of protective immunity to challenge infection.

The fraction NP/HA (nucleoprotein/haemagglutinin) obtained from n-octyl-beta-D-glucopyranoside-treated influenza A H5N2 virus was highly enriched for NP with residual haemagglutinin. This preparation was incorporated in ISCOMs. This potent 'immunostimulating complex' induced the production of high antibody titres in turkeys. The NP/HA ISCOMs preparation was found to protect turkeys from both homologous and heterologous challenge infection as shown by reduced viral titres in the lung and trachea of vaccinated turkeys. Clearance of the virus from trachea and lungs was seen at late stages of infection. The vaccine also induced a cellular immune response as measured by T-cell proliferation and a delayed-type hypersensitivity response. The results reported in this study demonstrate that the NP/HA ISCOM vaccine is capable of inducing type-specific immunity and that it has potential utility as a vaccine in turkeys.

Animals↗
PubMed1993

Influence of Newcastle disease virus on the severity of Pasteurella anatipestifer infection in turkeys.

This study was designed to examine whether vaccine or virulent strains of Newcastle disease virus (NDV) would potentiate the disease caused by Pasteurella anatipestifer infection in turkeys. The studies were conducted in turkeys of two age groups. There were three experiments. In two experiments four-week-old turkeys were exposed either to vaccine or virulent strains of NDV after experimental P anatipestifer infection. In the third experiment 14-week-old turkeys were first exposed to virulent NDV and superimposed with P anatipestifer infection. In experiment 1, one bird died where P anatipestifer was given in combination with the vaccine strain of NDV. However, there was no difference in the clinical signs, gross lesions and histopathology compared with turkeys given P anatipestifer alone. In experiment 3 where turkeys received a virulent strain of NDV in combination with P anatipestifer, birds became dyspnoeic and showed signs of illness. There was a difference in the course of the disease, gross lesions and histopathology when compared with turkeys that received P anatipestifer only.

Animals↗
PubMed1993

Effect of intravenous inoculation of avian influenza virus on reproduction and growth in mallard ducks.

An avian influenza virus isolate, A/Mallard/Ohio/184/86 (H5N1), was evaluated for its effects on reproduction in isolation-reared adult mallard ducks (Anas platyrhynchos) and growth rate in juvenile mallards after intravenous inoculation. There was a significant decrease in egg production in the experimental group during the first week after inoculation, but it returned to the normal production level during the second week. No effect was seen on egg weight, shape, or fertility. Ducklings receiving this influenza virus isolate did not differ from controls in their rate of growth.

Animals↗
PubMed1993

Antigen-capture enzyme immunoassay for detection of avian influenza virus in turkeys.

A double-antibody sandwich ELISA (DAS-ELISA) was developed for detection of avian influenza virus (AIV) antigen. A monoclonal antibody to the viral nucleoprotein (NP) was used to coat the ELISA plates. A direct DAS-ELISA and an indirect DAS-ELISA were evaluated. In the direct DAS-ELISA, monoclonal antibody to the AIV NP conjugated with horseradish peroxidase was used. The direct DAS-ELISA was evaluated for its sensitivity to detect purified NP; this procedure detected as little as 0.1 ng. In the indirect DAS-ELISA, rabbit NP antibody and horseradish peroxidase-conjugated goat anti-rabbit immunoglobin were used as primary and secondary antibodies, respectively. The indirect DAS-ELISA was evaluated for its ability to detect the AIV antigen in tracheal and cloacal specimens from turkeys inoculated with AIV. Results of indirect DAS-ELISA were compared with those of conventional virus isolation. Percentage agreement between indirect DAS-ELISA and virus isolation in AIV-positive samples was found to be 76.1% and, in AIV-negative samples, it was found to be 82.1%. These results indicate that the DAS-ELISA might be a viable alternative to virus isolation because of its rapidity, compared with virus isolation.

Animals↗
PubMed1992

Enhancement of antibody response of turkeys to trivalent avian influenza vaccine by positively charged liposomal avridine adjuvant.

Trivalent avian influenza (AIV) antigens (H4N8, H5N2 and H7N3), mixed with positively charged, negatively charged and neutral avridine-containing liposomes, and oil-emulsion were subcutaneously administered to 6-week-old turkeys. Charged liposomal avridine adjuvant, either positive or negative, produced a better antibody response than uncharged liposomal avridine or oil-emulsion adjuvants when used in a trivalent avian influenza vaccine. The antibody response to the different antigens was generally greater to the positively charged adjuvanted vaccine compared with the negatively or neutral charged or oil-emulsion adjuvanted vaccines and these differences were significant (P less than 0.05) with the three antigens. The results suggest that the positively charged liposomal avridine plays a significant role as adjuvant to the AIV antigens.

Adjuvants, Immunologic↗
PubMed1991

A quantitative measurement of the effect of avian influenza virus on the ability of turkeys to eliminate Pasteurella multocida from the respiratory tract.

The effect of avian influenza virus (AIV) infection on the ability of turkeys to eliminate Pasteurella multocida from the respiratory tract was evaluated. Four-week-old turkeys were experimentally infected with an apathogenic AIV subtype (H5N2) by the oculonasal route and subsequently superinfected with P multocida (Urbach strain) by the intranasal route three days after infection with AIV. Quantitative clearance of P multocida from the trachea and lung was determined using a pour plate technique on samples collected at intervals after infection. Samples from turkeys which had been infected with AIV were found to yield more P multocida than those from turkeys which had not been infected with AIV. The numbers of P multocida increased in infected birds to a greater extent than in birds which had not been infected with the virus. The present study suggests that AIV infection may contribute to the increased numbers and a decreased clearance of P multocida in turkeys.

Animals↗
PubMed1991

A retrospective analysis on the epizootiological aspects of outbreaks of Pasteurella anatipestifer infection in turkeys in Minnesota.

The possible risk factors associated with outbreaks of Pasteurella anatipestifer infection in turkeys were analyzed to study the epizootiology of the disease. The data for the study was obtained from flocks affected and unaffected with Pasteurella infection. The results of the analysis suggested that overcrowding, preexisting viral infections, increased activity of wild birds on the farm, and shorter down time were possible factors that initiate the occurrence of the disease in turkey flocks. The statistical models used in the analysis predicted correctly 80% of the unaffected flocks (8 out of 10 flocks), and 95% of the affected flocks (13 out of 14 flocks). The overall correct prediction was 88% (21 out of 24 flocks). Fish meal and meat and bone meal, which are integral components of turkey feed, were analyzed for the possible presence of P. anatipestifer. Its presence in a sample of fish meal was demonstrated.

Animal Feed↗
PubMed1988

Efficacy of infectious bronchitis virus vaccines against heterologous challenge.

Twenty-four-week-old white Leghorn layers were inoculated subcutaneously with a killed Newcastle disease-infectious bronchitis (Massachusetts type) virus (MIBV) vaccine. Twenty-eight weeks after vaccination, the birds were challenged intraocularly with the Arkansas strain of infectious bronchitis virus (AIBV) to determine the effects of heterologous virus exposure on egg production, egg quality and serum antibody response of the birds. The challenged hens laid significantly (P less than 0.005) fewer eggs than the unchallenged layers. Eggs laid by the unchallenged groups weighed significantly more (P less than 0.005) than those laid by the challenged groups. Further, the internal quality (Haugh units) and shell quality of eggs laid by the AIBV-challenged hens was significantly (P less than 0.005) inferior to those from the unchallenged hens. In addition, the AIBV-challenged hens laid more soft-shell, misshapen and small eggs than the unchallenged hens. The Arkansas serum haemagglutination inhibition (AIBV-HI) titres of AIBV challenged birds increased up to four weeks after challenge. The corresponding MIBV haemagglutination-inhibition (MIBV-HI) titres decreased during the same period. The study indicates that killed MIBV vaccine offered no protection to birds exposed to heterologous AIBV.

Animals↗
PubMed1987

Use of temperature-sensitive gel for concentration of influenza virus from infected allantoic fluids.

Cross-linked, poly(N-isopropylacrylamide) gel was used to concentrate avian influenza virus from allantoic fluid. Placing the gel in virus-infected allantoic fluid at 4 degrees C caused the gel to swell and absorb small molecular weight solutes, while excluding avian influenza virus and other large particles. Warming the gel to 37 degrees C or more caused the gel to collapse. The gel remained functional after sterilization in an autoclave and could be reused to concentrate other samples of allantoic fluid. Using a combined concentration and elution technique, we were able to achieve an average of 84.2% virus recovery, while reducing the fluid volume from 90 ml to 7.6 ml.

Acrylic Resins↗
PubMed1986

Standardization of enzyme-linked immunosorbent assay for avian influenza virus antibodies in turkeys.

The signal-to-noise ratio was useful in determining the optimal dilution of rabbit anti-turkey conjugate. Optimum dilution for rabbit anti-turkey conjugate to be used in the enzyme-linked immunosorbent assay (ELISA) was 1:1,000. The avian influenza virus antigen concentration was 128 hemagglutinating units (0.3 microgram of protein) per well, as determined by checkerboard titration. Bovine serum albumin fraction V increased nonspecific binding of conjugate and was not used to coat the plates in subsequent tests. Using ELISA, nonspecific binding to avian influenza virus-coated plates were not found with antibodies to Newcastle disease virus, infectious bursal disease, Salmonella, or Escherichia coli. Chromogens o-phenenediamine, and 2,2'-azino-di-(3-ethyl-benz-thiazoline sulfonic acid) were almost equal in sensitivity for detecting released oxygen from the H2O2. The substrate plate was more sensitive than was the polystyrene plate. Dual wavelength was reliable in reading ELISA results.

Animals↗
PubMed1985

Epizootiology of avian influenza: effect of season on incidence in sentinel ducks and domestic turkeys in Minnesota.

Sentinel ducks and domestic turkey flocks were monitored for influenza infection during a 4-year period. The onset of infection among ducks was similar each year, occurring in late July or early August. Influenza in turkeys was also shown to be seasonal, but the usual onset was 6 to 8 weeks after the detection of influenza in sentinel ducks. Possible explanations for the delayed infection in turkeys are (i) increased waterfowl activity associated with fledging and congregating in late summer and early fall; (ii) vectors transmitting virus from the waterfowl habitat to poultry farms; (iii) cooler environmental temperature, allowing prolonged virus viability; (iv) cooler surface water temperature, allowing prolonged virus viability; (v) groundwater contamination from contaminated surface water; and (vi) virus adaptation in domestic turkeys before infection is detected. We conclude that ducks are not only a natural reservoir of influenza but also have a seasonal infection that appears to be related to seasonal influenza outbreaks in domestic turkeys in Minnesota. However, only some influenza A virus isolates circulating among waterfowl at any given time appear capable of causing detectable infection in turkeys. It is speculated that the seasonal infection in migratory waterfowl may also be related to seasonal influenza infections in other species including humans.

Animals↗
PubMed1985

Field trials to test the efficacy of polyvalent Marek's disease vaccines in layer and broiler breeder chickens.

As a follow-up to earlier trials to evaluate the efficacy of polyvalent Marek's disease (MD) vaccines in broilers, four trials were conducted with layer or broiler breeder flocks. Chickens caccinated with trivalent (Md11/75C plus SB-1 plus HVT) and bivalent (SB-1 plus HVT) vaccines were compared with those vaccinated with turkey herpesvirus (HVT) alone. Data from three of the four trials indicated polyvalent vaccines were more efficacious than HVT. However, critical interpretations were confounded by low MD lesion frequencies, unequal exposure in different houses on a farm, and difficulty in the differential diagnosis of mortality due to neoplasms. The data confirmed our earlier observation that trivalent and bivalent vaccines were equally effective. Broiler progeny of breeders vaccinated or contact-infected with Serotype 2 MD virus were well protected by either bivalent or HVT vaccines against challenge with very virulent MD virus strains in the laboratory. A high incidence of lymphoid leukosis was observed in two trials and may have been due to post-hatch exposure to an unidentified environmental source of avian leukosis virus.

Animals↗
PubMedDate not supplied

Development, characterization, and preliminary evaluation of a temperature-sensitive mutant of Ornithobacterium rhinotracheale for potential use as a live vaccine in turkeys.

A temperature-sensitive (Ts) mutant strain of Ornithobacterium rhinotracheale (ORT) was developed after exposure of the wild-type organism to N-methyl-N'-nitro-N-nitrosoguanidine. The Ts mutant strain grew at 31 C but had its growth inhibited at 41 C unlike wild-type parent strain. The Ts mutant and parent strains were characterized. Morphologic and biochemical properties of wild-type and mutant strains did not show any differences. The strains were also characterized by polymerase chain reaction (PCR)-based fingerprinting methods. Results showed similar patterns in repetitive sequences by repetitive PCR (enterobacterial repetitive intergenic consensus, highly conserved repeated DNA elements present in Streptococcus pneumoniae (BOX), repetitive extragenic palindromic, and Salmonella enteritidis repetitive element primers); however, random amplified polymorphic DNA fingerprinting was able to differentiate mutant and parent strains showing a unique pattern for each of the ORT strains. The rationale for the use of a Ts strain as a vaccine is based on the ability of the mutant to colonize the upper respiratory tract but not the lower respiratory tract and systemic system of the birds, where the wild-type strain causes severe lesions. In a preliminary evaluation, Ts strain of ORT was recovered from tracheas and choanae of Ts-treated turkeys for 13 days postadministration of the strain either in drinking water or by oculonasal instillation. Humoral immune response was detected in Ts-vaccinated but not in control group birds after 3 wk postadministration. Results suggest that Ts strain of ORT has promising potential use as a live vaccine for ORT.

Animals↗
PubMedDate not supplied

Neonatal avian pneumovirus infection in commercial turkeys.

Eleven market turkey flocks developed a respiratory disease characterized by coughing, swollen sinuses and nasal discharge. These symptoms first appeared between 3 and 16 days of age. Avian pneumovirus (APV) RNA was detected by reverse transcriptase (RT)-polymerase chain reaction (PCR) in six of six flocks tested. APV was detected by immunohistochemistry in turbinates of three of three affected flocks tested. Virus isolation attempts were negative. Ten of 11 flocks became seropositive on the APV enzyme-linked immunosorbent assay. Five weeks prior to hatch of these affected market turkeys, several breeder flocks in one geographic area had developed clinical signs and experienced decline in egg production typical of APV infection. In two breeder flocks, acute and convalescent sera indicated APV infection during the period of declining egg production. Attempts to detect APV RNA by RT-PCR from choanal cleft swabs of newly hatched poults were successful. Attempts to isolate the virus from these PCR-positive samples were negative.

Age Factors↗
PubMedDate not supplied

Comparison of enzyme-linked immunosorbent assays and virus neutralization test for detection of antibodies to avian pneumovirus.

Two different whole-virus enzyme-linked immunosorbent assays (ELISAs), developed in Ohio (OH) with APV/Minnesota/turkey/2a/97 and in Minnesota (MN) with APV/Colorado/turkey/97, and the virus neutralization (VN) test were used to test 270 turkey serum samples from 27 Minnesota turkey flocks for avian pneumovirus (APV) antibodies. In addition, 77 turkey serum samples and 128 ostrich serum samples from Ohio were tested. None of the turkey samples from Ohio had antibodies to APV by the VN test and OH ELISA. The ostrich samples were only tested with the VN test and were all negative for antibodies to APV. For the Minnesota serum samples, 107, 115, and 120 were positive by the VN test, the OH ELISA, and the MN ELISA, respectively. The Kappa values of 0.938 and 0.825 showed excellent agreement between the VN test and the OH ELISA and the MN ELISA, respectively, for detection of antibodies to the APV. The OH ELISA and MN ELISA had sensitivities of 1.0 and 0.953, specificities of 0.950 and 0.889, and accuracies of 0.970 and 0.914, respectively. Our results indicate that the 3 methods are sensitive and specific for diagnosis of the APV infection.

Animals↗
PubMedDate not supplied

Survival of Ornithobacterium rhinotracheale in sterilized poultry litter.

Ornithobacterium rhinotracheale (ORT) has been associated with respiratory disease, increased mortality, retarded growth, and decreased egg production in chickens and turkeys. Surveillance of exposure to ORT infection in the field has shown that prevalence of the infection is higher during winter months. The ability of ORT to remain viable in the poultry litter was studied at different temperatures over time. Presterilized poultry litter was inoculated with 10(11) colony-forming units of ORT and kept at -12 C, 4 C, 22 C, 37 C, and 42 C. Reisolation and titration of ORT from litter was attempted at intervals. Results indicate that ORT survived for 1 day at 37 C, 6 days at 22 C, 40 days at 4 C, and at least 150 days at -12 C. ORT did not survive 24 hr at 42 C. The survival of ORT at lower temperatures may be associated with the higher incidence of ORT infection in poultry during winter months.

Animals↗
PubMedDate not supplied

Detection of avian pneumovirus in wild Canada (Branta canadensis) and blue-winged teal (Anas discors) geese.

Choanal cleft swab samples from 770 wild Canada geese (Branta canadensis) and 358 blue-winged teal (Anas discors), captured for relocation or banding, were examined for the presence of avian pneumovirus (APV) RNA by reverse transcription (RT)-polymerase chain reaction (PCR) and for virus isolation. The swab samples were pooled into groups of 5 or 10. Sixty eight of 102 (66.7%) pooled goose samples were RT-PCR positive for APV RNA. Thirteen of 52 (25.0%) pooled blue-winged teal samples were RT-PCR positive for APV RNA. APV RNA-positive samples were inoculated onto chick embryo fibroblasts (CEF) and QT-35 cells. Infectious APV was isolated from five Canada goose pooled samples in CEF and from one Canada goose pool in QT-35 cells but not from blue-winged teal.

Animals↗