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Biomedical subjects

A E Castro

Publications and source records attributed to A E Castro.

At least 19 recordsLinked to original sources
PubMed2003

Survival of avian influenza virus H7N2 in SPF chickens and their environments.

The survival or clearance of the avian influenza virus (AIV) of subtype H7N2 in its chicken host was evaluated using experimentally infected specific pathogen free (SPF) chickens of different age groups. Birds of different ages were successfully infected with infectious doses ranging between 10(4.7) and 10(5.7) ELD50 per bird. In infected birds, the infective virus was undetectable usually by the third week following exposure. The infectivity or inactivation time of the H7N2 AIV in various environmental conditions was studied using chicken manure, heat, ethanol, pH, and disinfectants. The H7N2 AIV was effectively inactivated by field chicken manure in less than a week at an ambient temperature of 15-20 degrees C. At a pH 2, heating at 56 degrees C, and exposure to 70% ethanol or a specific disinfectant, the AIV infectivity was destroyed in less than 30 min.

Animals↗
PubMed2003

Epidemiology, production losses, and control measures associated with an outbreak of avian influenza subtype H7N2 in Pennsylvania (1996-98).

An outbreak of H7N2 low-pathogenicity (LP) avian influenza (AI) occurred in a two-county area in Pennsylvania from December of 1996 through April of 1998. The outbreak resulted in infection of 2,623,116 commercial birds on 25 premises encompassing 47 flocks. Twenty-one (one premise with infection twice) of the twenty-five infected premises housed egg-laying chickens and one premise each had turkeys, layer pullets, quail, and a mixed backyard dealer flock. Despite dose proximity of infected flocks to commercial broiler flocks, no infected broilers were identified. Experimentally, when market age broilers were placed on an influenza-infected premise they seroconverted and developed oviduct lesions. The outbreak was believed to have originated from two separate introductions into commercial layer flocks from premises and by individuals dealing in sales of live fowl in the metropolitan New York and New Jersey live-bird markets. Source flocks for these markets are primarily in the northeast and mid-Atlantic areas, including Pennsylvania. Mixed fowl sold include ducks, geese, guinea hens, quail, chukar partridges, and a variety of chickens grown on perhaps hundreds of small farms. Infections with the H7N2 AI virus were associated with variable morbidity and temporary decreases in egg production ranging from 1.6% to 29.1% in commercial egg-laying chickens. Egg production losses averaged 4.0 weeks duration. Mortality ranged from 1.5 to 18.3 times normal (mean of 4.3 times normal). Duration of mortality ranged from 2 to 13 weeks (average of 3.9 weeks) in flocks not depopulated. Lesions observed were primarily oviducts filled with a mucous and white gelatinous exudates and atypical egg yolk peritonitis. Quarantine of premises and complete depopulation were the early measures employed in control of this outbreak. Epidemiological studies suggested that depopulation furthered the spread of influenza to nearby flocks. Thereafter, later control measures included quarantine, strict biosecurity, and controlled marketing of products.

Animals↗
PubMed2001

Single-tube single-enzyme reverse transcriptase PCR assay for detection of bovine viral diarrhea virus in pooled bovine serum.

A reverse transcriptase PCR (RT-PCR) was developed for use as a diagnostic screening test for the detection of bovine viral diarrhea virus (BVDV) in pooled bovine serum samples. Individual serum samples from 60 dairy cattle herds located in Pennsylvania were evaluated by the microplate virus isolation method, and pooled sera were analyzed by RT-PCR. RT-PCR was sensitive and specific and detected a single viremic serum sample in up to 100 pooled serum samples. RT-PCR analysis of pooled sera provides a rapid and cost-effective method for the screening of cattle herds for the presence of animals persistently infected with BVDV.

Animals↗
PubMed2000

Production and evaluation criteria of specific monoclonal antibodies to the hemagglutinin of the H7N2 subtype of avian influenza virus.

To enhance the rapidity in diagnosing the spread of avian influenza virus (AIV) in chicken layer flocks, studies were initiated to develop more sensitive and specific immunological and molecular methods for the detection of AIV. In this study, the purification of the hemagglutinin protein (H) from field isolates of H7N2, the production of monoclonal antibodies (MAbs), and their evaluation as diagnostic reagents are reported. Hybridomas were generated by fusion of SP2/0-Ag14 myelomas and spleen cells from immunized mice. Hybridomas secreting antibodies specific for the H protein were assayed by an ELISA and cloned using limiting dilution. The MAbs produced were characterized by hemagglutination inhibition (HI), immunohistochemistry (IHC), indirect fluorescent antibody assay (IFA), Western blots, and IFA flow cytometry using various AIV subtypes (i.e., H4N2, H5N3, H7N2). Of the various MAbs assayed, 6 had consistent and reproducible results in each of the assays used. The results obtained in this investigation enhanced the usage of the MAbs to viral H protein in the surveillance of AIV in chickens.

Animals↗
PubMed1997

A gene for isolated congenital ptosis maps to a 3-cM region within 1p32-p34.1.

Hereditary isolated congenital ptosis is an autosomal dominant disorder with incomplete penetrance characterized by a variable degree of unilateral or bilateral drooping of the upper eyelids. We report linkage of this disorder in a large family to markers on chromosome 1p. In our sample of 37 meioses, nine informative markers did not recombine with the disease. D1S2677 gave a maximum two-point LOD score of 8.8 on the assumption of 90% penetrance (theta = 0). D1S447/2733 and D1S1616 flank the disease locus, with two-point LOD scores of 5.6/6.6 (theta = .04) and 4.9 (theta = .05), respectively, defining a region of 2.8 cM. FISH of YACs containing flanking recombinant markers localizes the gene to chromosome 1p32-p34.1. These data establish a map location for an isolated congenital ptosis gene and demonstrate that this disorder is genetically distinct from other extraocular muscle-specific disorders such as congenital fibrosis of the extraocular muscles and blepharophimosis.

Blepharoptosis↗
PubMed1993

Detection of bluetongue virus in clinical samples by polymerase chain reaction.

A previously described bluetongue virus (BTV) serogroup polymerase chain reaction (PCR) assay was applied to clinical samples. The sensitivity of the BTV serogroup PCR was increased by the use of non-radioactive chemiluminescent hybridization. Unfractionated whole blood samples from rams experimentally inoculated with cell culture-adapted BTV-11 UC-8 were analyzed by virus isolation (VI) on Vero cells and PCR. VI and PCR were in agreement, with the exception of 3 blood samples that were VI negative and PCR positive. In semen spiked with BTV-11 UC-8, PCR detected as little as 1.6 x 10(2) plaque-forming units of BTV/ml of semen. BTV in the spleen of a sheep submitted for necropsy for suspect BTV infection was detected by both PCR and VI in embryonated chicken eggs. BTV PCR with nonradioactive chemiluminescent hybridization resulted in a level of sensitivity comparable to that of VI and likely more sensitive than VI on Vero cells for blood. This BTV PCR has great promise for rapid, sensitive, and specific detection of active BTV infection in a variety of clinical samples.

Animals↗
PubMed1993

PCR detection of group A bovine rotaviruses in feces.

A polymerase chain reaction (PCR) protocol has been developed for identification of bovine group A rotavirus infection in feces. Primers (20mers) complementary to 3' ends of double-stranded RNA genome segment 6 of bovine rotavirus NCDV strain were synthesized and used in PCR. Bovine rotavirus RNA from infected cell culture was employed to optimize the PCR protocol. Rotavirus-negative fecal samples were spiked with known quantities of bovine rotavirus, and the sensitivity of the PCR assay was determined. Fecal samples were extracted with phenol and treated to eliminate unidentified PCR inhibitor(s) in feces, and PCR was performed. PCR products were either visualized on ethidium bromide-stained agarose gels or detected by chemiluminescent hybridization. The sensitivity of the assay was 6 x 10(4) viral particles/ml of feces with ethidium bromide-stained agarose gel visualization or 6 x 10(2) viral particles/ml of feces with chemiluminescent hybridization. The PCR assay was applied to 18 fecal specimens from clinical cases. All 16 clinical samples that were positive for rotavirus by enzyme-linked immunosorbent assay (ELISA) or by ELISA and electron microscopy (EM) were positive by PCR. The 2 samples that were rotavirus negative by ELISA or by ELISA and EM were also negative on PCR analysis.

Animals↗
PubMed1993

Restriction endonuclease analysis of herpesviruses isolated from two peninsular bighorn sheep (Ovis canadensis cremnobates).

In 1989, herpesviruses were isolated from nasal swabs taken from two peninsular bighorn sheep (Ovis canadensis cremnobates) in the Anza-Borrego Desert State Park, San Diego County, California (USA). Using restriction endonuclease analysis (REA) with Pst1 enzyme, each isolate was found to be similar to the Cooper strain of infectious bovine rhinotracheitis virus (IBRV). The REA patterns of the two herpesviruses from bighorn sheep were typical of either field strains or vaccine strains of IBRV commonly associated with cattle in the USA.

Animals↗
PubMed1993

Comparison of herpesvirus isolates from falcons, pigeons and psittacines by restriction endonuclease analysis.

Field isolates of herpesviruses recovered from falcon, pigeon, and psittacine birds were compared by restriction endonuclease (RE) analysis using four separate enzymes. Pigeon and falcon herpesviruses had strikingly similar DNA cleavage patterns, while DNA cleavage pattern of virus isolates from a double-yellow headed Amazon and an African grey parrot had different genomic patterns to both the pigeon and falcon herpesviruses. These findings support the field observations that pigeon herpesvirus causes a fatal herpesviral infection in the livers of pigeon-eating falcons.

Animals↗
PubMed1990

A diagnostic method to detect alcelaphine herpesvirus-1 of malignant catarrhal fever using the polymerase chain reaction.

A sensitive diagnostic method specific for alcelaphine herpesvirus-1, causative agent of malignant catarrhal fever, has been developed. Based on the nucleotide sequence of the alcelaphine herpesvirus-1 genomic DNA, a pair of 30 nucleotide primers was selected and synthesized for detecting the virus genome using the polymerase chain reaction (PCR). The virus genome was detected in crude cell lysate using the amplification reaction.

Animals↗