Biomedical subjects

G Corthier

Publications and source records attributed to G Corthier.

77 records · Page 5Linked to original sources

PubMed1976

Swine fever: influence of passive immunity on pig immune response following vaccination with a live virus vaccine (Thiverval strain).

The influence of passive immunity on the immune response to swine fever virus (S.F.V.) was investigated in pigs injected with variable amounts of S.F.V. antibodies instead of piglets from immune sows. The passive immunity suppresses the primary serum antibody response normally observed after vaccination with the Thiverval strain of S.F.V. This inhibition is either partial or complete depending on the amount of injected antibodies. Whatsoever the passive immunity intensity, a priming occurred (even in absence of any detectable primary response). This priming was evidenced by the clinical signs and the type of immune response following a virulent challenge. Two vaccination routes were tested: intramuscular and intranasal: 48 pigs were checked and no significant differences established, concerning protective efficiency. Intranasal vaccination induced local antibody production in pharyngeal secretions. Even in the absence of any detectable immunoglobulin transudation from serum to these secretions, local antibody synthesis was completely inhibited in passively immunized animals.

Administration, Intranasal↗

PubMed1976

[Comparison of 2 in vitro methods of titration of antibodies neutralizing the classic swine plague virus].

Swine fever virus neutralization have been studied by the following method: variable plaque forming units numbers are mixed with a predetermined serum dilution. Infectivity is measured before (VO) and after (Vr) neutralization reaction. Neutralization index (N.I. = logVo/V) represent the difference between the two titers. It had been demonstrated that mass law is a good approximation to describe swine fever virus neutralization. So the most useful form in which to express the relation between N.I. and dilution logarithm (log D) is NI = NIo--K log D (I) where K is the constante corresponding to the slope of neutralization curve. A sligh K variation is observed according to immunoglobulin classes sharing antibody activity. Average K value is equal to 3. NIO is the NI obtained when extrapolating the curve to log D = o. These results have permitted to compare the two seroneutralization methods commonly used: "constant serum" method and "variable serum" method (determination of serum dilution inhibiting 50% of infectivity: D50). From formula (I) the following relation can be obtained: see formular. Theoretical and experimental log D50 values were appromaximatively the same (difference inferior or equal to 0.3). So D50 can be calculated by both methods.

Animals↗

PubMed1976

Sub-clinical swine fever: a survey of neutralizing antibodies in ther sera of pigs from herds having reproductive failures.

Sera harvested from breeding farms where reproductive failures were observed but where swine fever vaccination was not carried out, where tested for the presence of neutralizing antibodies specific for swine fever virus. Neutralization tests were performed in tissue culture using two viruses strains: the american serological variant "331" strain isolated by MENGELING (1969) and the virulent "normal strain" Alfort. For comparison, sera harvested from healthy, vaccinated and unvaccinated breeding farms were also tested. Results show absence of antibodies against these two strains in healthy and unvaccinated animals. All sera harvested from healthy and vaccinated breeding farms have high levels of neutralizing activity against the two strains. From 1,251 harvested unvaccinated breeding farms have reproductive failures, 6.2 p. 100 had neutralizing antibodies against the "Alfort" strain and 17.1 p. 100 contained neutralizing antibodies against the "331" strain. In 87 out of these 189 breeding farms, positive serological reactions were observed. Considering the respective intensity of neutralizing activity against the two strains , the vaccination with live virus vaccines ("Chinese strain" or "Thiverval" strain) induces high levels of antibodies but a higher titer against "Alfort" strain. Inversely, low virulent strains responsible for sub-clinical swine fever induce low or moderate levels against the "331" strain and nil or low levels against the "Alfort" strain. These results suggest that low virulent strains having common antigenic properties with the serological variant "331" strain are circulating among pigs in unvaccinated breeding farms having reproductive failures. These features are important for future development and establishment of routine serological checking for diagnosis and herd testing.

Animals↗

PubMedDate not supplied

Ability of two Clostridium difficile strains from man and hare to produce cytotoxin in vitro and in gnotobiotic rodent intestines.

Cytotoxin production by human (VP1) and hare (FD) strains of Clostridium difficile were compared both in vitro in a broth culture and in vivo in intestinal contents of gnotobiotic rodents. Strain VP1 produced about 1,000 times more cytotoxin than the FD strain, both in vitro and in vivo, although the population levels of the two strains were not significantly different either in vitro or in vivo. Ninety percent of gnotobiotic rats and 100% of gnotobiotic mice established with the VP1 strain died within 3 days, whereas no mortality in rats or mice was observed with the FD strain. The cytotoxin titre increased during the 3 weeks following establishment of the FD strain in mice, decreasing thereafter. Mice previously established with the FD strain were protected from VP1 strain challenge. Cytotoxin production was greatly decreased in diassociated mice, although the population levels of the two strains did not differ to a great extent.

Animals↗

PubMedDate not supplied

[Health effects of lactic acid bacteria ingested in fermented milk].

Health effects of lactic acid bacteria ingested in fermented milk. Many recent studies have shown the health effects of various strains of lactic acid bacteria in humans and animals and have tried to describe their action mechanism in the digestive tract. A number and a variety of potential beneficial effects have been published. Some of these effects have already been described such as the improvement of lactose digestion and the treatment of diarrheal disorders. Other health effects are still a subject of controversy such as the decrease of serum cholesterol and the reduction of tumor formation. The aim of this article is to summarize the probiotic effects of lactic acid bacteria, their mechanisms, and the fate of these microorganisms during their transit in the digestive tract.

Animals↗