Biomedical subjects

Y M Saif

Publications and source records attributed to Y M Saif.

At least 73 records · Page 4Linked to original sources

PubMedDate not supplied

Experimental bovine coronavirus in turkey poults and young chickens.

The DB2 calf strain of bovine coronavirus (BCV) was used to inoculate 1-day-old specific-pathogen-free (SPF) turkey poults in three trials. In all trials, the birds developed clinical signs of enteritis at 48-72 hr postinoculation. Birds euthanatized at 3, 5, and 7 days postinoculation (DPI) had flaccid, pale intestines with watery contents, and the ceca were markedly enlarged with frothy contents. Coronavirus particles were detected by immune electron microscopy with BCV antibodies from the intestinal contents of birds killed at 3, 5, 7, and 12 DPI. Body weights of inoculated poults killed at 3, 5, and 7 DPI were significantly reduced as compared with controls. Hemagglutinating antibodies were detected in sera of convalescent birds at 12 DPI. However, experimental inoculation of 1-day-old SPF chicks in two trials with the same virus resulted in no clinical signs or macroscopic or microscopic lesions. No coronaviruses were detected from intestinal contents, and there were no significant differences in body weights of inoculated and noninoculated control chicks.

Animals↗

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Immunogenicity and antigenicity of very virulent strains of infectious bursal disease viruses.

The immunogenicity and antigenicity of three very virulent (vv) strains of infectious bursal disease viruses (IBDVs) from Turkey (OA), Holland (HOL), and Taiwan (PT) were investigated, and their antigenic relationships with the American classic SAL, variant IN serotype 1, and serotype 2 OH IBDVs were studied. In the present study, the vvIBDVs were passaged eight times in chicken embryos and were characterized by reverse transcription/polymerase chain reaction-restriction fragment length polymorphism with restriction enzymes MboI and BstNI. The restriction fragment length polymorphism profile patterns of these viruses did not change after eight passages in chicken embryos. Attempts were unsuccessful in adapting the vvIBDVs to replicate in vitro after six passages in primary cell cultures of chicken (chicken embryo fibroblast cells, chicken kidney embryo cells, and chicken embryo bursal cells), five passages in established cell lines (LSCC-RP9 and LSCC-RP12 B-lymphoblastoid cells, chicken macrophage [MQ-NCSU] cells, quail [QT35] cells), and 10 passages in vero and BGM-70 cells. Because it was not possible to adapt the vvIBDVs to cell culture, the antigenic relatednesses between these viruses and the American strains were established by cross-neutralization tests in chicken embryos, and the relatedness values were calculated with the Archetti and Horsfall formula. The results revealed that the vvIBDVs are antigenically related to the classic SAL strain but are antigenically different from the variant IN strain and serotype 2 OH virus. For the immunogenicity study, inactivated vaccines prepared from the vvIBDVs and containing 10(5) mean embryo lethal dose of each virus induced different levels of protection. The vaccines provided full protection against the classic STC strain but provided no protection against the variant IN strain at 5 and 10 days postchallenge.

Adaptation, Physiological↗

PubMedDate not supplied

Detection and persistence of infectious bursal disease virus in specific-pathogen-free and commercial broiler chickens.

In an earlier study, specific-pathogen-free (SPF) chickens were inoculated with infectious bursal disease virus (IBDV) at 3 wk of age. Their bursas were examined for virus at different intervals postinoculation (PI) by reverse transcriptase (RT)/polymerase chain reaction (PCR) and by virus isolation in chicken embryos up to 21 days PI. The RT/PCR was positive, but attempts to isolate infectious virus from bursal homogenates failed. This prompted us to investigate the persistence of IBDV or its RNA in the bursa of Fabricius (BF) of inoculated and vaccinated SPF chicks and of inoculated and vaccinated commercial broiler chicks that have maternally derived antibodies. Four trials were conducted in SPF and commercial broiler chickens. Infectious virus was detected by embryo inoculation up to 7 days PI in the BF of SPF chickens inoculated at 2 or 3 wk of age and up to 21 days PI by RT/PCR, whereas the viral RNA was detected by RT/PCR for up to 28 days PI. In SPF chicks inoculated at 1 day of age, the bursa-derived virus or its RNA was detected at 7 and 14 days PI when inoculated at a high dose (10(4) mean embryo infective dose [EID50]/bird) or at a low dose (10(2.5) EID50/bird). In commercial 1-day-old broiler chicks, the bursa-derived virus was detected at 7 and 14 days PI when inoculated at a high dose (10(4) EID50/bird), whereas the virus was detected only at 14 days PI when inoculated at a low dose (10(2.5) EID50/bird). In SPF and commercial chicks vaccinated with a modified live IBDV vaccine, the virus or its RNA was detected at 7 and 14 days postvaccination in SPF chicks, but neither the live vaccine virus nor its RNA was detected in commercial broilers vaccinated at 1 day or 2 wk of age.

Animals↗

PubMedDate not supplied

Pathogenicity of cell culture-derived and bursa-derived infectious bursal disease viruses in specific-pathogen-free chickens.

That passage of infectious bursal disease virus (IBDV) 30 and 40 times in an established cell line (BGM-70) resulted in loss of pathogenicity has been reported; however, both viruses maintained antigenicity and immunogenicity. That the passaged virus might have lost some ability to replicate in the natural host, resulting in lack of antigenic stimulation and a poor immune response, was speculated. In this study, the pathogenicity and the replication of the serorype 1 variant IN strain were investigated in specific-pathogen-free (SPF) chickens. The original bursa-derived virus was passaged 10 times (low passage [LP]) and 47 times (high passage [HP]) in BGM-70 cells. Two concentrations of the LP virus were used for inoculation of different groups of birds, high titer 1.5 x 10(5) 50% mean embryo infective dose (EID50) and low titer 1.5 x 10(2) EID50. Birds inoculated with the bursa-derived virus had significantly (P < 0.05) small bursas with severe inflammation and necrosis throughout the 21-day experimental period. Bursa and spleen/body weight ratios and bursal lesion scores of the birds inoculated with the LP and HP viruses were not significantly different from those of the uninoculated control group at any time postinoculation (PI). Virus replication in the bursa of Fabricius was investigated by virus isolation in SPF chicken embryos, immune electron microscopy (IEM), immunofluorescence (IF), and antigen-capture enzyme-linked immunosorbent assay (AC-ELISA). The virus was isolated from bursal tissues from birds inoculated with the bursa-derived virus from day 3 (first isolation attempt) through day 10 PI, and the highest virus concentration was detected at 3 days PI. Low virus titer was detected only at 3 days PI in chicken embryos inoculated with the bursal homogenates from birds inoculated with the LP virus at a high dose or the HP virus. No virus was isolated from birds inoculated with the LP virus at a low dose or the uninoculated control group. The virus antigen was also detected in bursal tissues collected from birds inoculated with the bursa-derived virus at 3, 5, and 7 days PI by IEM and AC-ELISA and until day 10 PI by IF. No virus antigen was detected in bursal tissues collected from birds inoculated with the cell culture-adapted viruses by embryo inoculation, IEM, IF, or AC-ELISA. The virus or its RNA was detected in the bursal homogenates up to 21 days PI by reverse transcriptase/polymerase chain reaction. These results indicated that adaptation of IBDV to BGM-70 cell culture resulted in a significant reduction in the ability of the virus to replicate in the bursa of Fabricius, and, consequently, no lesions were detected.

Animals↗

PubMedDate not supplied

Induction of functional defects in macrophages by a poult enteritis and mortality syndrome-associated turkey astrovirus.

The interaction of a poult enteritis and mortality syndrome (PEMS)-turkey astrovirus-Ohio State University (TAst-OSU) with the mononuclear phagocytic system cells, namely macrophages, was examined after in vitro and in vivo exposure. In vitro exposures were performed by incubating adherent turkey macrophages with various volumes of 10(6) 50% embryo infective dose (EID50)/ml TAst-OSU stock, whereas for in vivo challenge, poults were given a 200 microl inoculum of 10(6) EID50/ml TAst-OSU stock at 7 days of age. Results show that TAst-OSU in vitro exposure reduced macrophage viability relative to controls (P < 0.05) and decreased phagocytosis (P < 0.05) and intracytoplasmic killing of Escherichia coli (P < 0.05) after a 42-48-hr exposure. Poults challenged with TAst-OSU in vivo recruited almost 50% fewer Sephadex-elicited inflammatory cells in the abdominal cavity (P < 0.05) as compared with the sham controls. Similar to in vitro exposure, macrophages isolated from in vivo TAst-OSU-challenged poults exhibited reduced percentage of phagocytic macrophages (P < 0.05) as well as fewer intracytoplasmic E. coli per phagocytic macrophage (P < 0.05). TAst-OSU-challenged poults had a greater number of viable E. coli in their spleens (P < 0.05) after an intravenous E. coli challenge as compared with the non-TAst-OSU-challenged control poults. Macrophage-mediated cytokines and metabolites were also examined during this study. Both in vitro and in vivo TAst-OSU challenge resulted in reduced interleukin (IL)-1 and IL-6 activity. On the contrary, nitrite levels in macrophage culture supernatant fraction of TAst-OSU-challenged macrophages were significantly higher (P < or = 0.05). The findings of these studies indicated that TAst-OSU challenge induced defects in macrophage effector functions, implying that PEMS-turkey astrovirus can potentially impair the immune response of turkeys, thereby leading to enhanced susceptibility of turkeys to secondary, perhaps even fatal, bacterial infections.

Animals↗

PubMedDate not supplied

Antigenic and genomic relatedness of turkey-origin coronaviruses, bovine coronaviruses, and infectious bronchitis virus of chickens.

In earlier studies in our laboratory, we found that bovine coronavirus (BCV) was pathogenic for 1-day-old turkey poults. This finding prompted us to study the antigenic and genomic relatedness of turkey origin coronaviruses (TOCVs) to BCV. A one-step reverse transcription (RT)-polymerase chain reaction (PCR) targeting a 730-base pair fragment of the nucleocapsid (N) gene of BCV and a nested PCR targeting a 407-base pair fragment of the N gene were used in an attempt to detect TOCV from North Carolina, Indiana, and a prototype turkey coronavirus (TCV) obtained from the American Type Culture Collection. Both the one-step RT-PCR and the nested PCR amplified cell culture-passaged isolates of calf diarrhea strains of BCV but none of the 15 tested TOCVs or transmissible gastroenteritis coronavirus of swine. TOCVs also did not cross-react in a BCV antigen-capture (AC) enzyme-linked immunosorbent assay (ELISA) system with monoclonal antibodies (MAbs) against N, spike glycoprotein, and hemagglutinin esterase glycoprotein proteins of BCV as coating antibodies. The same TOCVs could be detected with primers designed from the genome of infectious bronchitis virus (IBV) of chickens. These primers amplified a 1082-base pair region spanning portions of the membrane glycoprotein (M) and N protein genes of IBV and TCV. The TOCVs also cross-reacted in an AC-ELISA with MAbs against the M and subunit 2 of spike glycoprotein of IBV.

Animals↗

PubMedDate not supplied

Effect of cell-culture passage on the pathogenicity and immunogenicity of two variant strains of infectious bursal disease virus.

Two variant strains of infectious bursal disease virus, IN and E, were adapted and passaged in an established cell line (BGM-70) 30 times and 40 times, respectively. Passage in cell culture resulted in loss of pathogenicity. However, both viruses maintained their antigenicity and immunogenicity, as demonstrated by the immunofluorescence and virus-neutralization tests and by the satisfactory protection induced by vaccinating specific-pathogen-free (SPF) chickens with inactivated preparations of both passaged viruses. No protection was induced when the passaged viruses were given to SPF chickens as live vaccines. It is speculated that the passaged viruses might have lost some ability to replicate in their natural host, resulting in lack of protection.

Animals↗

PubMedDate not supplied

Structural proteins of classic and variant strains of infectious bursal disease viruses.

Structural polypeptides of six tissue-culture-origin (BGM-70 continuous cell line) infectious bursal disease viruses representing classic and variant strains of serotype 1 and one serotype 2 strain were analyzed and compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Additionally, two of the variant strains were propagated in vivo in bursa of Fabricius and compared with those grown in cell culture. Differences among the structural proteins of serotype 1 viruses were minor and probably of no value in differentiating these viruses. However, distinct differences were observed between serotype 1 and 2 viruses. The bursa-derived viruses were different from those propagated in cell culture in molecular weights and in proportions of the proteins. The bursa-derived strains had protein migration patterns similar to those described for tissue-culture-incomplete virus particles.

Infectious bursal disease virus↗

PubMedDate not supplied

Genetic variation in resistance of turkeys to experimental infection with Newcastle disease virus.

Seven hundred eighty male and female turkeys representing four genetic lines were challenged in four experiments with the Texas GB strain of Newcastle disease virus (NDV). The lines of turkeys included two randombred control lines (RBC1 and RBC2), a subline (E) of RBC1 selected for increased egg production, and a subline (F) of RBC2 selected for increased 16-week body weight. Mortality in turkeys of subline F (32.5%) was significantly higher than that in turkeys of line RBC2 (15.8%), subline E (17.5%), and line RBC1 (18.4%). At the end of each experiment, surviving birds were tested for antibody to NDV using the enzyme-linked immunosorbent assay (ELISA) and hemagglutination-inhibition (HI) test. Turkeys of subline E and line RBC1 had significantly lower ELISA antibody titers than those of subline F and line RBC2. Subline F had the highest HI antibody titers, followed in decreasing order by lines RBC2 and RBC1 and subline E. No apparent correlation was found between antibody response and mortality after NDV challenge.

Animals↗

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Efficacy of Linco-Spectin medication on mycoplasma meleagridis airsacculitis in turkey poults.

The efficacy of Linco-Spectin (LS) water medication was determined against Mycoplasma meleagridis (MM) airsacculitis in turkey poults under controlled conditions. The poults were obtained from commercial flocks naturally infected with MM. Water medication was given for the first five days of life. In Georgia and Ohio, LS was given at 0, 1, 2, and 4 g per gallon of drinking water. In California and Minnesota, LS was administered at 0 and 2 g per gallon of drinking water. At three weeks old, the birds were weighed individually and examined serologically, culturally, and grossly for MM airsacculitis. LS at 2 g activity per gallon of drinking water was beneficial in controlling MM airsacculitis in all four trials.

Administration, Oral↗

PubMedDate not supplied

Immunogenicity of infectious bursal disease viruses in chickens.

Cross-protective properties of infectious bursal disease viruses (IBDVs) were studied. Viruses represented different subtypes of serotype 1, including recently isolated viruses (variants), and a serotype 2 virus. Chickens were vaccinated at 3 weeks of age with inactivated vaccines containing 10(5), 10(6), 10(7), or 10(8) mean tissue-culture infectious dose of a given virus and challenged 2 weeks later using either 10(2) or 10(3.5) mean embryo infectious dose (EID50) of either a standard virus or a variant serotype 1 virus. Protection was evaluated at 5 and 10 days post-challenge, based on gross and microscopic lesions, body weight, and bursa/body-weight ratios. The serotype 2 virus did not confer protection on birds challenged with the serotype 1 viruses. Vaccines made of variant viruses at the low doses protected chickens challenged with the high or low doses of either the standard or the variant viruses. Vaccines made of the standard or variant strains at low doses protected against high or low challenge doses of the standard strain. Vaccines made of the high dose of any of the standard strains protected chickens against the variant virus when the low challenge dose (10(2) EID50) was used, but not when the high challenge dose (10(3.5) EID50) was used. The lowest dose of the standard viruses vaccines required to confer protection against the variant virus varied depending on the strain. Results indicated that protection depended on the strain and dose of both the vaccine and challenge viruses and that the variant strains and standard strains share a common protective antigen(s).

Animals↗

PubMedDate not supplied

Genetic variation in resistance of turkeys to experimental challenge with Pasteurella multocida.

Six hundred fifty-five male and female turkeys representing four genetic lines were challenged in 10 experiments over a 3-year period with a field isolate of Pasteurella multocida. Poults were challenged at 45 days of age with 1 ml of an inoculum containing 1.2 x 10(7) bacteria per ml. The lines of turkeys included two randombred control lines (RBC1 and RBC2), a subline (E) of RBC1 selected for increased egg production, and a subline (F) of RBC2 selected for increased 16-week body weight. The number of days from exposure to severe clinical signs or death for Line F (5.8 days) differed significantly from that of Line E (8.2 days), Line RBC1 (8.0 days), and Line RBC2 (8.2 days). There were no significant differences due to sex of poult for number of days from exposure to severe clinical signs or death. Overall mortality observed was 51.2%. Mortality was highest for Line F (72.1%) and differed significantly from that of the other lines. Mortality among male poults did not differ significantly from mortality among female poults.

Animals↗

PubMedDate not supplied

Detection of antibodies against Bordetella avium in turkeys by avidin-biotin enhancement of the enzyme-linked immunosorbent assay and the dot-immunobinding assay.

An avidin-biotin-enhanced enzyme-linked immunosorbent assay (AB-ELISA) and an avidin-biotin-enhanced dot-immunobinding (AB-DIB) assay for detecting antibody to Bordetella avium in turkey sera were developed and compared with the microagglutination (MA) test. Whole-cell antigen, biotin-labeled goat anti-turkey IgG conjugate, and horseradish-peroxidase-labeled streptavidin were used in the AB-ELISA and AB-DIB assay. The AB-ELISA and AB-DIB assay were sensitive, specific, and reproducible. These assays were superior to the MA test for measuring acquired and maternal antibodies against B. avium. All MA-positive sera were positive by two assays, but some sera negative by MA test had titers in the AB-ELISA and AB-DIB assay. AB-ELISA and AB-DIB titers showed a positive correlation (r = 0.866), and AB-ELISA was more sensitive than the AB-DIB assay.

Agglutination Tests↗

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A small round virus associated with enteritis in turkey poults.

In a natural outbreak of enteric disease in turkey poults, Salmonella, group D rotavirus, astrovirus, and a small (18-24 nm) round virus were detected in the gut contents. Except for the small virus, the pathogenic potential of the other agents is recognized. In experiments, the small round virus was shown to be transmissible and pathogenic in specific-pathogen-free turkey poults.

Animals↗

PubMedDate not supplied

Infectious bursal disease virus variant from commercial Leghorn pullets.

An infectious bursal disease virus (IBDV) was isolated from 39-to-43-day-old commercial leghorn pullets suspected of having infectious bursal disease (IBD). These chickens had been vaccinated with a commercial live IBDV vaccine at 28 and 35 days of age. An isolate designated IN was recovered using specific-pathogen-free (SPF) chickens and the BGM-70 established cell line. Experimental studies using SPF chickens vaccinated with either inactivated vaccines made from the vaccine strain used in the problem flock or a standard-type vaccine indicated no protection against the IN isolate. However, two variants and another standard-type vaccine induced protection against the IN isolate. Cross-neutralization tests indicated that the IN isolate differed antigenically from commercial vaccine strains and was related to the variant IBDV strains recently isolated from broilers. To our knowledge, this is the first report of a variant IBDV recovered from commercial layer chickens in the United States.

Animals↗

PubMedDate not supplied

Enteric disease in specific-pathogen-free turkey poults inoculated with a small round turkey-origin enteric virus.

Four- and 5-day-old specific-pathogen-free turkey poults were inoculated orally or by contact exposure to a small round turkey-origin enteric virus. At days 4 and 8 postinoculation (PI), the orally inoculated poults had significantly lower body weight gains than control poults. Poults at day 4 (orally inoculated) and 5 (contact-exposed) PI had watery droppings, dilated thin-walled ceca filled with yellow foamy fluid, catarrhal small intestinal secretions, pale intestinal serosa, and mild lymphocytic enteritis. In addition, at day 4 PI, poults were lymphopenic, had intracytoplasmic crystalline arrays of 17.1 +/- 1.1 nm viral particles in the jejunal villar enterocytes, and had an 18-to-24-nm virus in intestinal contents. Analysis of morphometric data revealed mild shortening of villi in the duodenum and elongation of crypts in the duodenum and ileum during the late stage of the syndrome (day 8 PI). These findings suggest that the 18-to-24-nm virus can produce an enteric disease syndrome and that the acute clinical manifestation of this syndrome is not the result of morphologic change such as intestinal villus atrophy. The definitive identity of this 18-to-24-nm virus is not known; however, based on size and intracytoplasmic arrays of virus, it is most probably an enterovirus.

Animals↗

PubMedDate not supplied

Differentiation between antibodies to serotypes 1 and 2 infectious bursal disease viruses in chicken sera.

The usefulness of the virus neutralization (VN) test, the enzyme-linked immunosorbent assay (ELISA), and the agar gel precipitin (AGP) test in differentiating antibodies to infectious bursal disease virus serotypes 1 and 2 was investigated. Sera examined were from chickens that were challenged with live virus or inoculated with inactivated oil-emulsion IBDV vaccines or were both challenged and inoculated. Antibodies to serotypes 1 and 2 were differentiated by the VN test but not by the ELISA, and the AGP test was less than satisfactory.

Animals↗

PubMedDate not supplied

Sudden death syndrome in turkey hens.

A turkey breeder flock of 5600 31-week-old hens experienced an abrupt increase in daily mortality for a 2-day period. This higher mortality rate corresponded with the handling and moving of the hens 1 to 2 days before. No clinical illness was seen in the hens before carcasses were discovered. The four hens that were necropsied had small spleens, congested lungs, and enlarged livers. The most consistent histologic lesions were pulmonary hemorrhage and edema, and congestion of veins and capillaries in several visceral organs. One hen had subserosal hemorrhage of the oviduct and perirenal hemorrhage. The increased mortality pattern, the lack of clinical signs, and the histopathologic changes are consistent with a diagnosis of sudden death syndrome. The presence of concurrent inflammatory lesions in the lungs predisposed the hens to sudden death following the stress of handling and moving.

Animals↗