Intracerebral Infection of Mice with Haemophilus pertussis and Passive Protection by Hyperimmune Rabbit Sera

Abstract

The intracerebral invasion in mice by two Haemophilus (Bordetella) pertussis strains, a virulent strain and the strain 18-323 which is very virulent on intracerebral injection, was studied. The LD 50 of these strains differed by about a thousand times and the average slopes of the regression lines from which these were calculated differed significantly, (P=0.04 and P = O . O l ) . It was found that the number of organisms/mouse brain in infected animaIs reached a maximum count which was slightly higher for the more virulent strain, The day on which the maximum count was reached depended both on the dose of organisms and the strain used, but occurred always before the seventh day after injection. Further, a slightly lower maximum count was reached as the dose of organisms was decreased. The passive protection by rabbit sera, described as antibacterial and antitoxic sera, against both these strains of pertussis organisms, was studied. It was shown that the protection of neither type of serum was due only to the presence of agglutinin antibodies.

A comparison between the intranasal and intracerebral infection of mice with Bordetella pertussis

“…1C based on ), Blyth (1955, Andersen (1957) and Brown (1958 Until the blood-brain barrier becomes permeable, the brain is free from circulating antibody and provides all the necessary growth conditions so that very small inocula, probably down to a single cell if it becomes lodged in the brain, can and will grow up to the critical level . It is therefore not surprising that with a virulent strain sublethal infections do not occur.…”

“…There is some reaction in the brain as Blyth (1955), Andersen (1957) and Brown (1958) all reported sublethal infections with strains of low mouse virulence. In Blyth's (1955) example an inoculum of 1025 had grown to 104 by the 5th day, the numbers then declined until the 10 mice examined on the 21st day had sterile brains.…”

The Pathology And Immunology Of Bordetella Pertussis Infection

“…At the 4th day the count in the brain of the immune mouse begins to decrease, and the brain is virtually sterile by the 6th-7th day. The brain viable count at which the decrease begins is, like the lethal viable count, a constant at about 105-106 organisms (Brown, 1958;Dolby and Standfast, 1958); it is at about this time that a breakdown in the blood-brain barrier occurs, with passage of polymorphs and plasma protein into the ventricles (Holt et al, 1961).…”