A COTTON RAT MODEL OF EFFECTORS OF IMMUNITY TO RESPIRATORY SYNCYTIAL VIRUS OTHER THAN SERUM ANTIBODY

A model for studying effecters of immunity to respiratory syncytial vi rus (RSV) was developed. Pairs of inbred cotton rats (Sigmodon hispidu s) were joined surgically using the technique of parabiosis. One week later, one animal of each pair was primed intranasally with a small vo lume of RSV suspension. Fourteen days after priming, both animals of e ach pair were bled for determination of serum neutralizing antibody ti ters, and challenged intranasally with a standard dose of RSV suspensi on. Single, unprimed cotton rats were challenged concomitantly and ser ved as controls. Four days after challenge, all animals were sacrifice d for virus titration of nasal tissues and lungs. Parabiosed cotton ra ts were surgically separated at varying intervals between priming and challenge (days 7, 9, 12, or 14 after priming) or were kept joined unt il sacrificed (day 18). Significant transfer of nasal and pulmonary im munity from primed to unprimed parabionts began 9 days after priming, gradually increasing through 18 days. Resistance to RSV challenge in s pite of low levels of serum neutralizing antibody suggests that non-an tibody immunologic mediators were responsible for the transferred immu nity. Evidence is presented for three broad categories of RSV immunolo gic effecters: systemic, local with a transient systemic phase, and lo cal without a systemic phase. These categories are now amenable to fur ther study using the described model. Pediatr Pulmonol, 1995; 19:355-3 59. (C) 1995 Wiley-Liss, Inc.