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M Grayon

Publications and source records attributed to M Grayon.

31 records · Page 2Linked to original sources
PubMed1992

Molecular typing of Brucella with cloned DNA probes.

Brucella constitutes a single genomic species (B. melitensis); however, for epidemiological studies, methods are needed for discriminating strains within this genomic species. DNA samples from 112 Brucella strains were cleaved by restriction endonucleases and the fragments separated by agarose gel electrophoresis and transferred to nylon membranes. When the DNA fragments on the membranes were probed with 32P-labelled 16 + 23 S rRNA from Escherichia coli, a single rRNA gene restriction pattern was obtained after cleavage with all endonucleases tested (HindIII, EcoRI, SmaI, and XhoI) except BamHI. This indicated high genomic homogeneity within the single Brucella species. Of 30 probes consisting of random Brucella DNA fragments cloned into lambda EMBL3, 20 yielded a single BamHI restriction pattern per probe when applied to 112 Brucella DNA tested. However, 7 probes yielded 3 to 12 different patterns among DNA tested. These patterns more-or-less correlated with the classification of strains into biogroups (Melitensis, Abortus, Suis, Neotomae, Ovis and Canis) and biovars (18 biovars represented). Probe A was capable of separating biogroup Melitensis from the other biogroups. Probe C separated the set of biogroups Melitensis-Abortus-Ovis from the other biogroups. By reference to the patterns obtained using 1 to 7 probes, the most frequently occurring biovars (Melitensis 1, Melitensis 3, Abortus 1, Abortus 3, Suis 2 and Ovis) could be distinguished from each other. Eight biovars showed more than one pattern with 1 to 7 probes. The proposed typing system should be useful for epidemiological subtyping and does not pose safety problems once the DNA has been extracted.

Autoradiography↗
PubMed1992

Conjunctival vaccination of pregnant ewes and goats with Brucella melitensis Rev 1 vaccine: safety and serological responses.

When Brucella melitensis strain Rev 1 vaccine (Rev 1) is administered by the standard method (1-2 x 10(9) viable bacteria injected subcutaneously), it may induce long-lasting serological responses and/or cause abortion in pregnant animals. The conjunctival route considerably reduces these drawbacks. In the present experiment a 1 x 10(8) CFU dose for both ewes and goats conjunctivally vaccinated at mid-pregnancy was tested for innocuousness (outcome of pregnancy, contamination of unvaccinated contact animals, duration of serological responses) in comparison with 3 x 10(8) CFU (ewes and goats), 1 x 10(9) and 3 x 10(9) CFU (ewes) doses. No reaction was observed at the time of vaccination, and the risk of environmental contamination with Rev 1, due to the conjunctival administration of the vaccine, is negligible. Abortions occurred later at surprisingly severe rates (over 60% of pregnant vaccinated animals), except in the 1 x 10(8) CFU ewes group (20%). Moreover, the serological reactions of the 1 x 10(8) CFU ewes which normally lambed were negative again as early as 12 weeks after vaccination. Although the dose of 1 x 10(8) CFU Rev 1 was safer for pregnancy than the standard dose mainly in ewes as compared to goats, the innocuousness was not yet sufficient to propose the former dose to indiscriminately vaccinate sheep and goats by the conjunctival route, whatever the age or physiological status.

Abortion, Veterinary↗
PubMed1989

[Bovine brucellosis caused by Brucella melitensis in France].

Each Brucella species is known to have a definite host preference. In this respect, brucellosis in cattle is primarily due to B. abortus. As part of an investigation of the species and biovars responsible for bovine brucellosis in France, 312 strains have been examined since 1978 by the methods recommended by the Subcommittee on the Taxonomy of the genus Brucella. Of these, 264 (85%) were indeed classified as B. abortus members. However the 48 others (15%) had all the characteristics that define the species B. melitensis which usually affects small ruminants. Of these 48 strains, 43 (90%) came from the southern part of France in which B. melitensis infection in sheep and goats is enzootic and where the dissemination of this species by sheep flocks moving to mountain pastures most often accounted for cattle contamination. Evidence that B. melitensis infection in cattle traced to infected small ruminants was also strongly supported by biotyping. Of the 48 strains, 45 (94%) indeed were B. melitensis biovar 3 which is the most common in infected sheep and goats in France. B. melitensis infected cattle, which also constitutes a serious risk for public health, must therefore be considered by veterinary authorities because of epizootiologic implications in eradication and control programmes of sheep and goat brucellosis.

Animals↗
PubMed1987

Conjunctival vaccination of young goats with Brucella melitensis strain Rev 1.

Three groups each of 15 four-month old female kids were vaccinated with Brucella melitensis strain Rev 1 either conjunctivally (1.1 x 10(7) or 1.1 x 10(9) CFU) or subcutaneously (1.1 x 10(9) CFU). One group of 15 kids remained unvaccinated as control. All kids were mated when 9.5 month old. Three months later, they were challenged conjunctivally with B melitensis strain H38 at a dose of 5.1 x 10(6) CFU. Blood samples collected before vaccination and throughout the experiment were subjected to Rose Bengal (RBPT) and Complement Fixation (CFT) tests. Allergy was tested both after vaccination and after challenge. Milk, uterine discharge as well as tissues from aborted foetuses and dead kids and from goats slaughtered 4-6 weeks after abortion or full-term kidding, were cultured on Farrell's medium. A serological response was shown in most kids vaccinated conjunctivally. However, 4 months after vaccination with either 1.1 x 10(7) or 1.1 x 10(9) CFU Rev 1, all animals were negative whereas some positive RBPT or CFT titres were still observed after the classical subcutaneous vaccination. There were more allergic reactions among subcutaneously than conjunctivaly vaccinated animals, but sensitization was shown long-lasting in all vaccinated groups, excluding allergic testing as a screening method in vaccinated flocks. Against a challenge which led all controls to abort, conjunctival vaccination was slightly better with 1.1 x 10(9) than with 1.1 x 10(7) CFU and almost as effective than that given by the subcutaneous one. These differences however were not statistically significant. These results quite agree with those previously recorded for ewes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

[Characteristics of 273 strains of Brucella abortus of African origin].

273 Brucella strains from Africa have been examined for identification and typing in our laboratory, since 1976. Of these, 213 were isolated from Senegal, 30 from Togo, 12 from Morocco, 10 from Rwanda, 7 from Guinea Bissau and 1 from Niger. 272 strains were from cattle. Most of them (260) were from native animals that showed hygromas. 12 strains from Morocco were isolated from aborted calves of the "Pie Noire" dairy breed. One strain was from a human case of Brucellosis in Rwanda. All the strains were classified as members of B. abortus species by the recommended methods of the Subcommittee on Taxonomy of the genus. Of them, 269--including the human strain--were biotype 3/6. The others--2 from Morocco, 1 from Senegal and 1 from Rwanda--were biotype 1. Comment is needless about the 12 strains isolated from imported "Pie Noire" cattle. Their characteristics are identical with those of the B. abortus same biotypes isolated out of Africa. On the other hand, three unusual characteristics distinguish the 260 strains from native cattle and the human one from the main group of B. abortus: their growth characteristics, their mean oxidative profile and--for 219 of them--a negative oxidase test. The unusual behaviour of native B. abortus strains is discussed from an epidemiological and taxonomical point of view.

Africa↗
PubMed1982

Characteristics of Togo strains of Brucella abortus from cattle.

Thirty Togolese strains of Brucella from cattle were classified as members of B. abortus biotype 3 by the recommended methods of the Subcommittee on Taxonomy of this genus. However two unusual characteristics distinguish the Togolese strains from the main group of B. abortus: their mean oxidative profile altered on four of the conventional substrates (L-asparagine, L-arabinose, D-galactose and D-xylose) and their very slow growth on usual media. These two original characteristics are discussed from an epidemiological and taxonomical point of view.

Animals↗
PubMed1975

[Brucella isolated in France: identification and typing. I. -- Brucella abortus (author's transl)].

Two hundred and eight strains of Brucella isolated from cattle and 5 isolated from man in various areas of France, during a two-year period from 1972 to 1974, were examined by all methods recommended by the Subcommittee on Taxonomy of the genus Brucella and were found to have the same characteristics that identify and define the species Brucella abortus. Of the 213 strains, 105 (49,29 p. 100) were biotype I, 103 strains (48,36 p. 100) biotype 3, three strains (1,41 p. 100) biotype 4 and 2 strains (0,94 p. 100) biotype 2. The distribution of Brucella abortus biotypes isolated from cattle and man in France is reviewed and compared with the data from our sample. It corroborates the epidemiologic importance of Brucella abortus biotype 3, just after type 1, and the absence of biotypes 5 to 9(1) in France. Five strains of Brucella abortus biotype 3, originating from a well-defined geographical area, are ureaseless. This new biochemical character distinguishes these strains from the main group of biotype 3 and is discussed from an epidemiological and methodological point of view. Data on the oxydative rates obtained on 12 substrates by the 213 strains are presented in graphic form which reveals a metabolic profile for the species Brucella abortus. The interest of this graphic presentation is discussed and its use should be recommended.

Animals↗
PubMedDate not supplied

Differentiation of Brucella melitensis, B. ovis and B. suis biovar 2 strains by use of membrane protein- or cytoplasmic protein-specific gene probes.

The possibility of differentiating Brucella species and biovars by Southern blot hybridization of agarose gel-electrophoresed HindIII-digested genomic DNA with membrane protein- or cytoplasmic protein-specific gene probes was investigated on 92 reference and field strains representative of all known species and biovars. Based on the RFLP pattern observed, three gene probes, i.e. br25, 39ugpa and omp16 coding for membrane or cytoplasmic proteins differentiated B. melitensis, B. ovis and B. suis biovar 2 strains from each other and from the other Brucella species and biovars. Thus, the use of these specific gene probes could contribute, in addition to previously identified species- or biovar-specific markers, to the molecular identification and typing of Brucella isolates.

Animals↗
PubMedDate not supplied

[Brucella isolates in France: evaluation of 10 years of typing].

With the aim of knowing more exactly what species and biotypes are responsible for brucellosis in France, 2,058 strains have been examined since 1972. Of these, 1,693 were isolated from cattle, 190 from sheep, 10 from hare, 9 from goats, 3 from swine and 3 from field mice (Apodemus sylvaticus); 150 were of cases of human infection. Of the 18 types presently recognized for the genus Brucella, 11 were identified within the sample. In animal strains, they were B. abortus biotypes 1, 2, 3, 4 and 9, B. suis biotypes 1 and 2, B. melitensis biotypes 1, 2 and 3, and B. ovis. All these types--except B. suis 2 and B. ovis--were identified within the human strains. Of these 11 types, 3 were widely predominant both in man and animals: B. abortus biotypes 1 and 3 and B. melitensis biotype 3, which together total 84.2% of the sample's strains. The results also emphasized the preference of B. abortus, B. melitensis and B. ovis for a decided animal host: 99.4% of the bovine strains were B. abortus, 98.1% of those isolated from ewes and goats were B. melitensis, and all the B ovis strains were from cases of ram epididymitis. Of the 150 human strains, 115 were B. melitensis, 33 B. abortus and 2 B. suis. These data were discussed from a taxonomical and epidemiological point of view.

Animals↗
PubMedDate not supplied

Brucella melitensis infection in sheep: present and future.

Sheep brucellosis, a zoonosis mainly due to B. melitensis (biovar 1, 2 or 3), remains widespread world-wide. Pathologically and epidemiologically, the disease is very similar to B. abortus infection in cattle. The live B. melitensis Rev 1 strain is currently considered as the best vaccine available for the control of sheep brucellosis, especially when used at the standard dose by the conjunctival route. Used exhaustively in whole-flock vaccination programmes, it induces a great decrease in the prevalence in both sheep and human populations. The expensive test-and-slaughter strategy should be restricted to the lowest infected areas. Whenever possible, Brucella spp. should be isolated by culture using adequate selective media from uterine discharges, aborted fetuses, udder secretions or selected tissues, such as lymph nodes, testes or epididymides. Species and biovar identification is routinely based on cultural criteria, on lysis by phages and on simple biochemical and serological tests. The recently developed polymerase chain reaction methods provide additional means of detection and identification. Despite the high degree of DNA homology within the genus Brucella, several methods, including PCR-RFLP and Southern blot, have been developed which allow, to a certain extent, the differentiation between Brucella species and some of their biovars. While several ELISA tests have been developed recently, the rose bengal plate agglutination and complement fixation tests, based on the detection of anti-S-LPS antibody, are still recommended for screening flocks and individuals. However, these tests sometimes lack specificity or sensitivity. For pooled samples, there are no useful tests such as the milk ring test in cattle. The brucellin allergic skin test can be used as a screening or complementary test in unvaccinated flocks, provided that a purified, lipopolysaccharide (LPS)-free and standardized antigen preparation is used.

Animals↗