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Biomedical subjects

V Sivanandan

Publications and source records attributed to V Sivanandan.

At least 19 recordsLinked to original sources
PubMed1996

Active immunization against vasoactive intestinal peptide prevents photo-induced prolactin secretion in turkeys.

Photostimulation initiates and maintains the rise in circulating prolactin (PRL) observed during the reproductive cycle of the female turkey. Vasoactive intestinal peptide (VIP) is the principal PRL-releasing factor. This study tested the hypothesis that gonadal stimulatory photoperiods stimulate PRL secretion by releasing hypothalamic VIP. Therefore, an experiment was designed to determine if VIP immunoneutralization altered photo-induced PRL secretion. Reproductively quiescent female turkeys were divided into two groups comprising turkeys actively immunized with synthetic VIP conjugated to keyhole limpet hemocyanin (VIP-KLH; immunized; n = 48) or KLH alone (control; n = 48). The first immunization was administered 6 weeks before photostimulation. Blood samples were collected at frequent intervals prior to and following photostimulation, and plasma PRL concentrations were determined. Vasoactive intestinal peptide antibody titer was estimated from the percentage of 125I-labeled VIP bound to plasma diluted 1:1000. At the onset of photostimulation (Day 0), plasma PRL levels were similar for immunized and control turkeys (9.1 +/- 0.3 versus 8.9 +/- 0.3 ng/ml, respectively). Plasma PRL of control birds increased (P < 0.05) by Day 16 of photostimulation, reaching a peak value of 724.9 +/- 90.1 ng/ml on Day 84. In contrast, plasma PRL remained essentially unchanged in immunized birds. Titer of anti-VIP antibodies expressed as 125I-VIP bound by plasma in immunized birds was 10.9 +/- 1.5% on the day of photostimulation. Incubation behavior was blocked in immunized birds, whereas 75% of controls exhibited incubation behavior. The control group laid 1.83 eggs/ week/hen compared to 3.40 eggs/week/hen in immunized hens. These findings suggest that photoperiodic modulation of PRL secretion in the turkey is influenced by hypothalamic VIP neuronal system.

Animals↗
PubMed1996

A dot immunobinding assay (dot-ELISA) for the rapid serodiagnosis of Salmonella enteritidis infection in chickens.

A dot immunobinding assay (DIA) was developed for the detection of antibodies to Salmonella enteritidis. Western blot analysis of outer membrane proteins from SE identified 2 polypeptides of molecular masses 43 and 46 kD that were specific for S. enteritidis. These 2 polypeptides were utilized as antigens in the DIA. The DIA was tested on sera from chickens experimentally infected with S. enteritidis. Results of the DIA were compared with that of conventional microagglutination and serum plate tests. The DIA was a highly specific and sensitive test that can be useful for screening birds to determine if they are infected with S. enteritidis. Its simplicity, reliability, reproducibility, and speed in interpreting the assay results makes it a useful screening test for flock monitoring.

Animals↗
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↗
PubMed1994

Adjuvanted subunit vaccines for the control of Salmonella enteritidis infection in turkeys.

Liposomes and immunostimulating complexes (ISCOM) are adjuvants that have been known to potentiate the immune response to membrane proteins. Adjuvanted outer membrane proteins (OMP) from Salmonella enteritidis were evaluated for their protective efficacy against S enteritidis infection in turkeys. The adjuvanted vaccines prepared for evaluation were: positive or negatively charged liposomes, lipid-conjugated ISCOM, and mineral oil vaccines. These preparations were compared with that of a whole cell bacterin and protein alone. After vaccination, turkeys were challenge-exposed with a nalidixic acid-resistant strain of S enteritidis. They were monitored for clinical signs of disease, antibody response, bacterial shedding pattern, and clearance of the challenge S enteritidis from internal organs. Results indicated a significantly (P < 0.05) higher antibody response to the positively charged liposomal OMP vaccine, compared with the whole cell bacterin. The antibody response to positively charged liposomal OMP vaccine was greater when a booster dose of this preparation was given. Shedding of S enteritidis was decreased in all vaccinated and challenge-exposed turkeys (P < 0.001). The tissues from a high percentage (90 to 100%) of birds that received a booster vaccination of the liposomal (+ or -) and ISCOM vaccine were culture-negative for S enteritidis.

Adjuvants, Immunologic↗
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

Identification and characterization of viral polypeptides from type-II avian adenoviruses.

The polypeptides of serologically related viruses of hemorrhagic enteritis (HE) in turkeys, marble spleen disease (MSD) in pheasants, and splenomegaly in chickens (SMC) were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and analyzed by protein immunoblotting with polyclonal antibodies to HE virus (HEV). The viral polypeptides II, III, IV, V, VI, and VII were detected on SDS-PAGE with the size range from 18 to 97 kDa in HEV. Viral polypeptides II, III, V, VI, and VII were detected in MSD virus and virus of SMC. Protein immunoblotting of viral proteins with anti-HEV serum revealed antigenic differences between the 3 viruses of avian adenovirus type-II examined. The differences were that the polypeptides II, III, IV, V, VI, and VII were identified in HEV and the polypeptides II, V, VI, and VII were identified in MSD virus and virus of SMC. The bands of penton base (polypeptide III) and fiber (polypeptide IV) were seen in HEV only by protein immunoblotting.

Adenoviridae Infections↗
PubMed1991

Decrease in pulmonary artery pressure with slow release nifedipine in Saudi patients with primary pulmonary hypertension.

We studied the acute and short-term hemodynamic effects of vasodilators in three Saudi patients with primary pulmonary hypertension. The study protocol included the measurement of pulmonary artery pressure, resistance and cardiac output at baseline and at 15, 30, 45 and 60 minutes after 10 mg sublingual nifedipine. These hemodynamic studies repeated at 3 and 6 months follow-up. A 24 hour profile of pulmonary artery and aortic pressures were recorded to evaluate the effect of 20 mg of slow release nifedipine, after 25 mg of captopril and 5 mg of sublingual isordil. After nifedipine there was a marked reduction in systolic pulmonary artery pressure from 85 +/- 18 to 55 +/- 8 mmHg and the pulmonary resistance decreased from 1422 +/- 367 to 954 +/- 69 dynes-sec/cm-5. The cardiac output increased from 2.9 +/- 0.2 to 0.2 to 4.0 +/- 0.4 l/min after nifedipine. The patients were discharged on nifedipine 10 mg qid, except for patient #3 who was a non-responder. At follow-up there was a symptomatic improvement and a favourable hemodynamic response was maintained, though patient #2 required a higher dose of nifedipine. The pulmonary artery 24 hour pressure profile revealed that 20 mg slow release adalat reduced pulmonary artery pressure for a 6 hour period. Whereas, regular nifedipine decreased pulmonary artery pressure for a period of less than 90 minutes. There was no favourable hemodynamic response to either captopril 25 mg oral of isordil 5 mg administered sublingually. We conclude that slow release nifedipine decreases the pulmonary artery pressure for longer periods compared to regular nifedipine in patients with primary pulmonary hypertension.

Adolescent↗
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↗
PubMed1986

Siderophore production by Pasteurella multocida.

Pasteurella multocida grown under conditions of iron deprivation secreted into the culture medium a growth-enhancing factor which functioned as a siderophore. The siderophore was found to be neither a phenolate nor a hydroxamate by chemical tests and bioassays and was given the trivial name multocidin. Multocidin was partially purified and found to be a highly polar, nonaromatic, and dialyzable compound. This is the first report demonstrating the production of a siderophore by P. multocida.

Culture Media↗
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

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↗
PubMed1984

Effect of ammonia on the quantitative clearance of Escherichia coli from lungs, air sacs, and livers of turkeys aerosol vaccinated against Escherichia coli.

Turkeys were given an aerosol vaccine to determine their ability to clear a virulent inhaled pathogenic strain of Escherichia coli, while they were being maintained in the presence of atmospheric NH3. Turkeys were exposed to 2 concentrations of NH3 (10 and 40 microliters/L of air). More E coli was found in lungs, air sacs, and livers of turkeys exposed to NH3. Turkeys not exposed to NH3 had better clearance of E coli. Vaccination against E coli improved the rate of clearance of E coli in birds not exposed to NH3.

Air Sacs↗
PubMed1984

Rapid purification of avian influenza virus for use in enzyme-linked immunosorbent assay.

A rapid and easy purification method was developed to obtain avian influenza antigen for use in immunochemical assays. This was achieved by rapid concentration of virus from infective allantoic fluid, using 8% (w/v) polyethylene glycol 8000, and later, by purification on gel-permeation chromatography through controlled-pore glass beads. Rabbit anti-turkey globulins were made specific for turkey globulins, using affinity chromatography, conjugated to horseradish peroxidase and used in enzyme-linked immunosorbent assay. A significant increase in specificity and sensitivity of the enzyme-linked immunosorbent assay was observed when purified antigen was used in place of a crude antigen preparation. This purified antigen eliminated the false-positives obtained as a result of the turkeys being previously vaccinated with egg-grown virus vaccines (Newcastle disease virus). The details of the technique and the importance of antigen preparation are discussed.

Animals↗
PubMed1984

Use of whole blood lymphocyte stimulation test for immunocompetency studies in bald eagles, red-tailed hawks, and great horned owls.

Mitogen-induced whole blood lymphocyte stimulation tests for immunocompetency studies in bald eagles (Haliaeetus leucocephalus), red-tailed hawks (Buteo jamaicensis), and great horned owls (Bubo virginianus) were developed. Combinations of incubation times, blood dilutions, concentrations of [3H]thymidine and [125I]2-deoxyuridine, antibiotics, phytohemagglutinin-P, and concanavalin A were tested for their effects on the stimulation index (SI). An antibiotic combination of gentamicin plus amphotericin B yielded low SI with lymphocytes from bald eagles, but not with lymphocytes from great horned owls or red-tailed hawks. Penicillin plus streptomycin caused no such depression of SI. Lymphocytes from all 3 species yielded maximum responses with a 48-hour prelabel and 12- to- 16 hour postlabel incubation period at 41 C and 1:20 blood dilution. Optimal mitogen concentrations for lymphocytes from bald eagles, red-tailed hawks, and great horned owls were 25 micrograms, 10 micrograms, and 10 micrograms of phytohemagglutinin-P/well, respectively, and 2.5 micrograms, 10 micrograms, and 10 micrograms of concanavalin A/well, respectively. Differences in SI were not seen between the 2 radioactive labels. The optimal concentration of the [3H]thymidine label ranged from 0.06 to 0.125 microCi/well.

Amphotericin B↗