Biomedical subjects

D A Halvorson

Publications and source records attributed to D A Halvorson.

80 records · Page 5Linked to original sources

PubMedDate not supplied

Effect of temperature on the stability of avian influenza virus antigens under different storage conditions.

The combined effect of time and temperature on the stability of two avian influenza virus (AIV) isolates concentrated with polyethylene glycol (PEG), stored at different temperatures, and used in the preparation of avian influenza vaccine was evaluated in turkeys at 24 hr and at 12, 24, 30, 36, and 42 months of storage. The differences detected between antibodies raised in turkeys by vaccines made from isolates under different storage conditions, times, and temperatures were not significant (P > 0.05), especially with vaccines prepared from one isolate. Virus recovery rates following challenge studies of vaccinated birds were similar. However, birds that were vaccinated twice had lower rates of virus recovery from the trachea, lungs, pancreas, and fecal samples following challenge infection. The results suggest that if stable isolates of AIV can be identified, such isolates can be rapidly concentrated with PEG and stored at -20 C or -196 C for at least 42 months without any loss of potency in the vaccine prepared from these isolates. This would reduce the costs associated with vaccine storage and subsequent expiration dates.

Animals↗

PubMedDate not supplied

Early chick mortality associated with rupture of the yolk sac.

Rupture of the yolk sac was identified in leghorn chicks from six placements of a commercial hatchery that had high mortality (up to 3%) during the first 3 days. The abdomens of these chicks were filled with cloudy yellowish fluid; kidneys were swollen, and many chicks also had severe visceral urate deposition (visceral gout). No significant bacterial growth was detected. The hatchery had recently hired new sexors. After the sexors were cautioned to handle the chicks more carefully, the problem abruptly subsided. In an experimental attempt to reproduce the condition, a graded series of doses (0, 0.5, 1.0, 2.0, and 4.0 ml) of egg yolk were injected intraperitoneally into five groups of twenty 1-day-old chicks. Twelve of the 20 chicks that received the 4-ml dose died. They developed swollen, pale kidneys and had cloudy yellow fluid in the abdominal cavity, but no visceral urate deposition. Only six of the remaining 80 chicks that received lesser doses or no yolk died.

Animal Husbandry↗

PubMedDate not supplied

Description of osteomyelitis lesions associated with Actinomyces pyogenes infection in the proximal tibia of adult male turkeys.

Actinomyces pyogenes was isolated from osteomyelitis lesions from the proximal tibia of mature tom turkeys. Gram-stained impression smears of the lesions resulted in bacteria that appeared as club-shaped, gram-positive pleomorphic rods. The bacteria grew better in a reduced-oxygen environment. The lesions were well demarcated and cavernous, ranging from purulent to caseous in consistency.

Actinomycosis↗

PubMedDate not supplied

Excessive mortality in market-age turkeys associated with cellulitis.

Between July, 1993, and October, 1994, seven cases were examined that consisted of increased mortality in commercial turkeys due to cellulitis. The condition started at 13-16 wk of age in toms and persisted until the birds were marketed. The mortality rate was 1-2% per week. Lesions began on the ventrum of the tail and consisted of swelling and the formation of vesiclelike structures. Most of the affected birds also had an accumulation of gelatinous fluid in the subcutis of the tail and breast areas. The underlying musculature was often darkened or petechiated. Clostridium perfringens type A was isolated from two of the cases. Lesions similar to those found in the field were reproduced experimentally in turkeys injected with the subcutaneous fluid obtained from birds in field cases.

Animals↗

PubMedDate not supplied

A dot immunoblotting assay (dot blot ELISA) for early detection of Newcastle disease antibodies in chickens.

An enzyme-linked immunosorbent assay using nitrocellulose blotting membrane (dot blot ELISA) was developed for the detection of antibodies against Newcastle disease virus (NDV) in chickens. In this method, a nitrocellulose blotting membrane was used as the solid phase carrier. NDV antigens were directly bound onto the nitrocellulose membrane that was set into a dot blot microfiltration apparatus. Efficiency of the assay was evaluated using known positive and negative NDV sera obtained from chickens. The ability of the assay to detect antibodies 2 days earlier than the standard hemagglutination-inhibition (HI) test was demonstrated on sera collected from chickens experimentally infected with NDV, La Sota strain.

Animals↗

PubMedDate not supplied

Ornithobacterium rhinotracheale infection in turkeys: experimental reproduction of the disease.

This report details the first experimental production of clinical disease, mortality, and pathology resembling that of field infections by using Ornithobacterium rhinotracheale alone. Twenty-two-week-old male turkeys were exposed to O. rhinotracheale or lung homogenate from O. rhinotracheale-infected turkeys. Within 24 hr after inoculation, turkeys given O. rhinotracheale or lung homogenate intratracheally were depressed and coughing and had decreased feed intake. By 48 hr, several birds were coughing blood and ultimately died. Grossly, the lungs were reddened, wet, and heavy, failed to collapse, and were covered by tenacious tan-to-white exudate. Microscopically, the parabronchi and air capillaries were filled with fibrin, heterophils, macrophages, and small numbers of gram-negative bacteria. The pleura was often covered by a thick layer of fibrin, heterophils, and macrophages. Turkeys that survived to day 7 postinoculation had severe, subacute pneumonia. Ornithobacterium rhinotracheale was recovered from the lungs of most birds with pneumonia and was also cultured from the air sacs, sinuses, tracheas, spleens, and livers. All turkeys inoculated with O. rhinotracheale developed antibodies to O. rhinotracheale detectable by the serum plate agglutination test.

Animals↗

PubMedDate not supplied

Efficacy of combined killed-in-oil emulsion and live Newcastle disease vaccines in chickens.

Following the introduction of routine vaccination regimes with different types of Newcastle disease (ND) vaccines, the incidence of velogenic viscerotropic Newcastle disease (VVND) in commercial poultry worldwide has declined dramatically. Unfortunately, these vaccination regimes are not feasible in free-range and backyard systems of poultry production practiced in many developing countries. In this study, we sought to develop a single vaccination regime in chickens with ND vaccines to elicit a long-lasting high level of ND virus (NDV) antibodies adequate to protect chickens against ND. The level of antibody response, as measured by the hemagglutination-inhibition (HI) test, and the degree of protection against the virulent strain of NDV were studied in chickens immunized with different vaccines. The vaccines used were: killed-in-oil emulsion (subcutaneous; s.c.) plus live virus (oculanasal; o.n.), given concurrently; experimental vaccine (s.c.) plus live virus (o.n.), given concurrently; killed-in-oil (s.c.); experimental vaccine prepared by homogenizing commercial live vaccine and oil emulsion (s.c.); and live virus (o.n.). The results obtained in this study indicate that concurrent administration of oil emulsion and live NDV vaccines induced the best antibody response, but there was no significant difference in protection among the vaccinated groups.

Animals↗

PubMedDate not supplied

Isolation and identification of Ornithobacterium rhinotracheale from commercial turkey flocks in the upper midwest.

Increased death loss was seen in a flock of 22-wk-old tom turkeys. The predominant postmortem lesion was fibrinopurulent pneumonia and pleuritis. Within 5 wk, turkey flocks on 17 other farms developed similar problems. All affected flocks during the 5-wk period were between 14 and 22 wk of age, and the severity of clinical signs and the degree of mortality increased with age. Ornithobacterium rhinotracheale was isolated in pure culture from affected lungs. Further investigation by tracheal swab culture of 261 flocks between 5 and 7 wk of age resulted in detection of O. rhinotracheale in 43% of the flocks.

Animals↗