Animal Diseases Research Institute

In this study, the polymerase chain reaction (PCR) was used in the detection of the attaching and effacing (eae) gene of Shiga-like toxin-producing Escherichia coli (SLT-EC). Oligonucleotide primers, complementary to the 5' portion of the eae gene of the enteropathogenic E. coli E2348/69 (O127:H6) and of SLT-EC CL8 and EDL933 (O157:H7), generated PCR products of the predicted sizes with DNA from the majority of human clinical SLT-EC strains tested from O serogroups 5, 26, 103, 111, 121, 128, 145, and 157; all SLT-EC strains of O serogroups 5, 26, and 111 from cattle; and a minority of porcine SLT-EC strains (one strain each from O serogroups 107 and 130 and one rough strain). Five HaeIII digestion profiles were obtained for PCR products generated by amplification of a 2.3-kb DNA fragment from the 5' end of eae. The HaeIII profiles for SLT-EC O serogroups, such as 26, 103, and 157, differed from each other but were consistent among strains within these O serogroups. Oligonucleotide primer pairs complementary to the 3' end of either the O127:H6 E. coli or the O157:H7 eae nucleotide sequence only amplified DNA from E. coli strains from a few of the SLT-EC O serogroups examined. One primer pair with homology to the 3' nucleotide sequence of eae from E. coli O157:H7 appeared to be relatively specific for this O serogroup by PCR. No PCR products were obtained in amplification experiments with the eae primers using DNA from human SLT-EC of O serogroups 38 (1 0f 1) and 91 (3 or 3), 15 of 15 SLT-EC strains from edema disease, or 29 of 29 non-SLT-EC strains from pigs and calves with diarrhea.

Abstract Considerable uncertainty still exists regarding the detailed arrangement in protein‐lipid molecular associations found in serum lipoproteins, plasma‐membranes of cell organelles, the myelin sheath of nerve, and many other structures of paramount importance to biological mechanisms both in health and disease. Working hypotheses concerning such structures must eventually be tested by comparing known properties with those suggested by exact stereomodels. In this type of study, orthogonal projections of the molecules offer several advantages over the tri‐dimensional stereomodels from which they can be derived by a described photographic process. The rules governing the configuration to be given the molecular models used for this purpose are discussed, and the possible applications of the resulting diagrams are described and illustrated by numerous examples taken in the lipid field. These rules are then applied to the lipids in the myelin sheath of nerve. Striking similarities in the configurational features of the two main classes of myelin lipids, the phosphatidyl (dal) and the sphingolipids, immediately suggest very similar models for them. On the other hand, numerous independent observations have indicated the highly probable occurrence of bimolecular complexes involving members of either class with cholesterol. Such complexes are exemplified by proposed models of cholesterol‐lecithin and cholesterol‐sphingomyelin units. It is demonstrated that the cohesional forces at play should indeed promote stable complexes of this kind. All configurational features of the lipids in myelin fit these basic models. Dimensional variations induced by a broad spectrum of component fatty acids, affect only the length of the resulting complex units. Moreover, the tail‐to‐tail arrangement of these units provides paired elements of the same length. The latter corresponds exactly to the fundamental dimension predicted for the bimolecular leaflet by low angle X‐ray diffraction studies on fresh, unfixed myelin. A model of the bimolecular lipid leaflet produced by parallel grouping of the paired elements is discussed.

Data are presented to show that there are three serum fl-globulin types in laboratory mice controlled by a pair of alleles. Each allele appears to give rise to three electrophoretically distinct zones in starch gel. Within the inbred strain AI AGS there was variation between mice in the intensity of staining of the three zones. Reciprocal mating data gave no evidence of an effect of fl-globulin type on segregation ratios as has been reported for cattle.

A rapid and sensitive method for detection of Shiga-like toxin (SLT)-producing Escherichia coli (SLT-EC) with the polymerase chain reaction (PCR) is described. Two pairs of oligonucleotide primers homologous to SLTI and SLTII genes, respectively, were used in multiplex PCR assays. The first pair generated a ca. 600-bp PCR product with DNA from all SLTI-producing E. coli tested but not from E. coli strains that produce SLTII or variants of SLTII. The second pair generated a ca. 800-bp PCR product with DNA from E. coli strains that produce SLTII or variants of SLTII but not from SLTI-producing E. coli. When used in combination, the SLTI and SLTII oligonucleotide primers amplified DNA from all of the SLT-EC tested. No PCR products were obtained with SLT primers with DNA from 28 E. coli strains that do not produce SLT or 44 strains of 28 other bacterial species. When ground beef samples were inoculated with SLT-EC strains 319 (O157:H7; SLTI and SLTII), H30 (O26:H11; SLTI), and B2F1/3 (O91:H21; SLTII variants VT2ha and VT2hb) and cultured in modified Trypticase soy broth for 6 h at 42 degrees C, an initial sample inoculum of as few as 1 CFU of these SLT-EC strains per g could be detected in PCR assays with DNA extracted from the broth cultures.

Caspofungin acetate (MK-0991) is an antifungal antibiotic that inhibits the synthesis of 1,3-beta-D-glucan, an essential component of the cell wall of several pathogenic fungi. Caspofungin acetate was recently approved for the treatment of invasive aspergillosis in patients who are refractory to or intolerant of other therapies. The activity of 1,3-beta-D-glucan synthesis inhibitors against Aspergillus fumigatus has been evaluated in animal models of pulmonary or disseminated disease by using prolongation of survival or reduction in tissue CFU as assay endpoints. Because these methods suffer from limited sensitivity or poor correlation with fungal growth, we have developed a quantitative PCR-based (qPCR) (TaqMan) assay to monitor disease progression and measure drug efficacy. A. fumigatus added to naïve, uninfected kidneys as either ungerminated conidia or small germlings yielded a linear qPCR response over at least 4 orders of magnitude. In a murine model of disseminated aspergillosis, a burden of A. fumigatus was detected in each of five different organs at 4 days postinfection by the qPCR assay, and the mean fungal load in these organs was 1.2 to 3.5 log(10) units greater than mean values determined by CFU measurement. When used to monitor disease progression in infected mice, the qPCR assay detected an increase of nearly 4 log(10) conidial equivalents/g of kidney between days 1 and 4 following infection, with a peak fungal burden that coincided with the onset of significant mortality. Traditional CFU methodology detected only a marginal increase in fungal load in the same tissues. In contrast, when mice were infected with Candida albicans, which does not form true mycelia in tissues, quantitation of kidney burden by both qPCR and CFU assays was strongly correlated as the infection progressed. Finally, treatment of mice with induced disseminated aspergillosis with either caspofungin or amphotericin B reduced the A. fumigatus burden in infected kidneys to the limit of detection for the qPCR assay. Because of its much larger dynamic range, the qPCR assay is superior to traditional CFU determination for monitoring the progression of disseminated aspergillosis and evaluating the activity of antifungal antibiotics against A. fumigatus.

A coalescence-based maximum-likelihood method is presented that aims to (i) detect diversity-reducing events in the recent history of a population and (ii) distinguish between demographic (e.g., bottlenecks) and selective causes (selective sweep) of a recent reduction of genetic variability. The former goal is achieved by taking account of the distortion in the shape of gene genealogies generated by diversity-reducing events: gene trees tend to be more star-like than under the standard coalescent. The latter issue is addressed by comparing patterns between loci: demographic events apply to the whole genome whereas selective events affect distinct regions of the genome to a varying extent. The maximum-likelihood approach allows one to estimate the time and strength of diversity-reducing events and to choose among competing hypotheses. An application to sequence data from an African population of Drosophila melanogaster shows that the bottleneck hypothesis is unlikely and that one or several selective sweeps probably occurred in the recent history of this population.

Although dogs are the most widespread and abundant of all carnivores, the role of the dog in human cultures and its impact on the environment have rarely been studied. These subjects are reviewed in the context of canine rabies. To understand the epizootiology of canine rabies, the ecology and population biology of the dog must be considered. Information on dog populations (in relation to different habitats, cultures, social strata of human populations and epizootiological situations) was collected in Nepal, Sri Lanka, Switzerland and Tunisia. In Switzerland (and Western Europe in general), rabies is maintained and spread by red foxes. The low prevalence of rabies in dogs may be explained by restrictive practices of dog-keeping and high rates of vaccination. In the other areas examined, dogs are poorly supervised and their population densities are high enough to support rabies, although it is questionable whether canine rabies exists independently of a wildlife reservoir. Dog-keeping practices, high rates of exposure and various cultural factors may lead to a high human rabies mortality rate. Nevertheless, dogs in these areas remain sufficiently accessible for vaccination and well-executed control programmes could prove successful.

Cryopreservation of sperm, embryos and, more recently, oocytes plays an important and increasing role in assisted reproduction, due to improvements of old, and introduction of new technologies. In parallel, concerns are increasing about the technical and biological safety of these procedures. However, published data regarding the confirmed or theoretical hazards of these procedures are sparse and sometimes contradictory. The purpose of this review will summarize data and opinions about one of the most disputed risks, the potential hazard of contamination and disease transmission through cryopreservation. Special attention is concentrated on the weak points of the technology including open vitrification systems, sterilization of liquid nitrogen and safety of commonly used storage tanks including straws and cryovials. Suggestions are also made for practical measures to avoid these dangers while preserving the benefits and perspectives of new cryopreservation technologies.

A sensitive and specific method for detection of Listeria monocytogenes in milk and ground-beef samples is described. It consists of culturing samples in listeria enrichment broth (LEB) and subculturing them from LEB to listeria plating media, followed by DNA extraction and species-specific detection of the organism by using the polymerase chain reaction (PCR). In developing the L. monocytogenes PCR assay, five oligonucleotide primers complementary to the nucleotide sequence of the listeriolysin O gene were synthesized and used in amplification experiments. PCR products of the predicted size, based on nucleotide sequence information, were generated with DNA from all of 72 L. monocytogenes strains with five different primer pairs. DNA from Listeria ivanovii, Listeria innocua, Listeria seeligeri, Listeria welshimeri, Listeria grayi, and Listeia murrayi strains and a panel of 47 bacterial strains representing 17 genera did not generate PCR products with the primer pairs employed. As little as 1 pg of L. monocytogenes DNA could be detected with the assay. To determine the most sensitive culture protocol to use in conjunction with the PCR assay, milk (10 ml) and ground-beef (25 g) samples were inoculated with L. monocytogenes at concentrations ranging from 0 to 10(5) CFU ml-1 or g-1, as appropriate for the sample. PCR assays on DNA extracted from growth on listeria plating media, inoculated with 24-h LEB samples cultures, were most sensitive, allowing detection of as little as 0.1 CFU of L. monocytogenes ml-1 or g-1 of milk and ground beef, respectively.

Synopsis A taxonomic review is provided of imagines of the forty-one known British species of Culicoides Latreille (Diptera, Ceratopogonidæ). Four species new to science, C. cameroni , C. reconditus , C. segnis and C. machardyi are described from the British Isles. The female of C. poperinghensis Goetghebuer is described for the first time. C. poperinghensis Goetghebuer and C. subfasciipennis Kieffer are recorded as new to the British Isles. C. lupicaris Downes and Kettle is defined anew. Distinguishing taxonomic characters are given for the females of C. achrayi Kettle and Lawson and C. pallidicornis Kieffer. A number of female structural characters of taxonomic importance are discussed and described for all the British species: the antennal sensilla are found to be important as a group character and antennal ratio as a specific or subspecific character. Descriptive notes with relevant taxonomic discussion are given for each species. The paper includes a key to species based on superficial characters and separate keys for each sex based on structural characters.

The effect on wool growth and the sulphur content of wool of supplements of L-oyswine, DL-methionine, and casein, given per abomasum a·s a continuous infusion, has been examined.

The onset of ovarian function and occurrence of estrus were monitored in two groups of Holstein cows over the first 90 days post-partum. Group 1 consisted of 36 animals housed in a free stall area and observed continuously for estrus with closed circuit television and a time lapse videorecorder. Group 2 consisted of 33 cows housed in tie stalls with estrus detected by the herdsmen. Blood samples were collected twice weekly and assayed for progesterone. The plasma progesterone profiles were used to monitor ovarian function and determine ovulation time. In both groups there was close agreement between basal progesterone concentrations and observed estrous activity. There was no difference between the groups in the incidence of abnormal ovarian activity, or in the interval from parturition to first, second or third ovulation. For all cows with normal ovarian function, the median time to first ovulation was 19.5 days and the time to the second and third ovulation was 44.4 ± 13.2 and 63.7 ± 10.1 days, respectively. A significant difference was observed between the two groups in the days from parturition to first detected estrus: Group 1, 34.5 ± 12.8; Group 2, 56.6 ± 26.5, (P>.01) and in the percentage of cows in which estrus was detected at the first, second and third ovulation: Group 1, 50%, 94% and 100%; Group 2, 20%, 44% and 64%, (P<.01).

Research Article| February 01 1942 Modified procedures for the colorimetric estimation of arginine and histidine Herbert Taylor Macpherson Herbert Taylor Macpherson 1Animal Diseases Research Association, Moredun Institute, Gilmerton, Midlothian Search for other works by this author on: This Site PubMed Google Scholar Biochem J (1942) 36 (1-2): 59–63. https://doi.org/10.1042/bj0360059 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation Herbert Taylor Macpherson; Modified procedures for the colorimetric estimation of arginine and histidine. Biochem J 1 February 1942; 36 (1-2): 59–63. doi: https://doi.org/10.1042/bj0360059 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Journal Search Advanced Search This content is only available as a PDF. © 1942 CAMBRIDGE UNIVERSITY PRESS1942 Article PDF first page preview Close Modal You do not currently have access to this content.

Permanent infection of a PK-15 (ATCC CCL-33) cell line by the porcine circovirus was demonstrated. This virus appears to be common in the Canadian swine population as indicated by the presence of antibodies detected by indirect immunofluorescence or immunoperoxidase tests in the serum of culled sows and sows in commercial herds. One source of the PK-15 cell line was found to be free of circovirus antigen.

Bovine peripheral blood mononuclear cells (PBMC) were labelled with monoclonal antibodies recognizing bovine MHC class II, sIgM, monocyte, T-helper and T-cytotoxic cell phenotypes. They were sorted into positive and negative populations with a fluorescence-activated cell sorter (FACS). The cell populations were infected in vitro with sporozoites of either Theileria annulata or T. parva, and the degree of infection and transformation determined. The results showed that despite the many similarities between these two parasites, they infected different cells of the immune system. T. annulata preferentially infected MHC class II-positive cells but did not infect T cells. Monocytes were infected very efficiently by T. annulata but were uninfectable with T. parva. B cells were infected much more efficiently by T. annulata than T. parva. Cell lines derived from infections with T. annulata were analysed phenotypically. Virtually all reactivity was lost for the anti-sIgM and the anti-monocyte monoclonal antibodies post-infection and no T-cell markers were detected.

Three experimental strains and two modern commercial stocks of meat-type chickens were compared in 1978. One experimental strain, K, an unselected control, represented broilers of 20 yr ago. A second experimental strain, A, selected for high broiler weight and a third, D, selected for high broiler and low adult weights had been derived from strain K and represented experimental strains genetically improved by artificial selection. All stocks were hatched and reared simultaneously using modern industrial practices. At 47 days, 70 birds of each sex and stock were slaughtered and the carcasses chemically analyzed. Also, 25 hens of each of strains A, D and K were slaughtered when 68 wk old and abdominal fat and carcass weight data were analyzed. The selection for higher broiler weight in strain A increased both broiler and adult body weights more and percent carcass fat less than the selection for high broiler and low adult weight in strain D. Relative to strain A, carcass weight of strain D was 10% lower in broilers and 16% lower in adult hens. Respective means for the modern commercial broilers, strain A broilers, and "broilers of 20 years ago" were 1552, 1001 and 676 g dressed carcass weight; 2.4, 1.6 and 1.4% abdominal fat; 17.2, 15.4 and 12.4% carcass fat (wet basis) and 1.90, 1.92 and 2.01 feed conversion. Thus, the modern broilers have a dramatically increased growth rate accompanied by higher fat content. The greater fat deposition may at least partly account for the lack of significant improvement in feed conversion.

Ten heifers were inoculated on two occasions with an inactivated preparation of tissue culture-grown calf rotavirus, and a further ten heifers received a placebo vaccine. Serum anti-rotavirus antibody titers were significantly increased throughout pregnancy in the vaccinated group. After calving, the mean neutralizing antibody titer of colostral whey in control cows was 100, associated with immunoglobulins A and G1. No antibody was detected in the milk of these cows after the 4th day postpartum. The colostral whey from the vaccinated cows had a mean antibody titer of 20,452; 28 days after calving, the mean milk antibody titer was 320, associated mainly with immunoglobulin G1. Calves were challenged with a large oral inoculum of calf rotavirus at the 7th day of age. There was significant lengthening of the incubation and prepatent periods in calves born to vaccinated dams, but rotavirus-associated diarrhea of equal severity occurred in both groups. Evidence is presented which suggests that rotavirus antibody in milk can protect against a smaller challenge dose. Maternal immunization against rotavirus may be a practical proposition.

An indirect (I) enzyme-linked immunosorbent assay (ELISA) and a competitive (C) ELISA, using a group-specific monoclonal antibody against bluetongue virus (BTV), are described for the detection of antibodies to BTV in cattle and sheep sera. The performance of these assays in detecting anti-BTV antibody in sequential serum samples and eluates from whole blood (WB) dried on filter paper from three calves and four sheep experimentally infected with type 10 BTV was evaluated. The C-ELISA was superior to the I-ELISA in the detection of anti-BTV antibody in the sera and WB samples from both cattle and sheep early after infection with BTV. BTV antibodies were demonstrable by C-ELISA in all the bovine and ovine sera and WB eluates by 9 days postinfection; whereas the I-ELISA results for sheep sera and WB eluates were similar, anti-BTV antibody was not detected in bovine serum and WB eluates until 26 and 14 days postinfection, respectively. While both ELISAs proved reliable, under the present test conditions involving detection of early postinfection reactions of experimentally infected animals, the C-ELISA was always as sensitive or more sensitive than the standard agar gel immunodiffusion test, the modified complement fixation test, and the plaque neutralization tests in the detection of anti-BTV antibodies. Unlike observations with the immunodiffusion test, no reaction was seen between BTV antigen and bovine epizootic hemorrhagic disease virus antiserum in either ELISA. The results suggest that either ELISA may be suitable for routine diagnostic testing and may have the potential to replace other tests for detection of anti-BTV group-specific antibodies and that the C-ELISA may have the most potential.

Some rotaviruses from calves, piglets, and lambs were detected by electron microscopic examination of faeces but not by an enzyme-linked immunosorbent assay which relies on detection of group antigen. On further examination by polyacrylamide gel electrophoresis, these viruses had 11 segments of dsRNA, as had typical rotaviruses, but arranged in atypical patterns. From humans, three rotaviruses with atypical electrophoretypes were also detected. Gnotobiotic animals were infected with atypical calf, piglet and lamb rotaviruses, and used to provide antigen and antiserum for an immunofluorescent comparison of these rotaviruses with conventional rotaviruses and other previously described atypical rotaviruses from piglets and chickens. Two atypical rotaviruses from humans failed to infect gnotobiotic piglets. The atypical rotaviruses could be tentatively categorized into two groups serologically distinct from each other and from conventional rotaviruses, and these distinctions were consistent with electrophoretypes . The atypical chicken rotavirus may form a fourth distinct group. These findings are consistent with the hypothesis that rotaviruses belong to at least four separate groups definable by serology and electrophoretype .

Fluorescence polarization assay (FPA) is based on the rotational differences between a small soluble antigen molecule in solution (labelled with a fluorochrome) and the antigen molecule complexed with its antibody. A small molecule will rotate randomly at a rapid rate, resulting in rapid depolarization of light, while a larger complex molecule will rotate slower and depolarize light at a reduced rate. The rate change in depolarization can be measured. The FPA is a homogeneous assay which does not require removal of unreacted reagents and can, therefore, be performed very quickly and, given portable equipment, in the laboratory and in the field. The latter obviates the need for shipping samples and eliminates waiting for results, as well as reducing test costs. The FPA technology has been developed and validated for the serological diagnosis of brucellosis in cattle, swine, sheep, goats, bison, and cervids. Sufficient cross reactivity of the common epitopes of Brucella abortus, B. melitensis and B. suis O-polysaccharide (OPS) allowed for the use of a single antigen for all species of smooth Brucella and animals. The OPS prepared from B. abortus S1119.3 was conjugated with fluorscein isothiocyanate (FITC). The FPA was initially developed for testing serum; however, the technology has been extended to testing whole blood and milk from individual animals or bulk tank samples pooled from 2000 or fewer animals. The accuracy of the FPA equalled or exceeded those obtained using other serological tests such as the buffered antigen plate agglutination test (BPAT), the milk ring test (MRT), the complement fixation test (CFT), the indirect enzyme immunoassay (IELISA), and the competitive enzyme immunoassay (CELISA).