Abstract 1039 Poster Session IV, Tuesday, 5/4 (poster 94)

Lactoferrin exhibits antiviral activity against RSV in vitro, and also has numerous immunologic properties. We determined the therapeutic effects of lactoferrin in a BALB/c mouse model of RSV infection. On day 0, respiratory rates (RR) and Penh (a measure of airway resistance) were obtained by whole body plethysmography on all mice. Groups of mice (5 males and 5 females per group) were then infected intranasally with 3.5×106 pfu of human RSV. Three groups of mice were treated with a solution containing either 0.1, 1.0 or 10 ug of recombinant human lactoferrin in 100ul saline (10, 100 and 1000nM) administered intranasally three times a day on days 2-5 following infection. The fourth group received 100ul of saline intranasally (untreated) on the same schedule. On day 6, plethysmography was repeated, animals were weighed and sacrificed, and the lungs were removed and weighed before processing for virus titration.

In untreated animals, RR increased from 247 bpm on day 0 to 354 bpm on day 6. RR in treated mice on day 6 were 285 (p = .0009), 326 (p = .09), and 308 (p = .014) in recipients of 10nM, 100nM and 1000nM of lactoferrin, respectively. Recipients of 10 nM lactoferrin also experienced less weight loss (p < .01) than untreated animals. These effects were greater in female mice than in males. Penh also increased between day 0 and day 6 (0.719 to 2.688, p < .001) in untreated, infected animals, indicating an increase in airway resistance. This increase was not altered by lactoferrin therapy. Neither lung weights nor quantity of virus recovered appeared to be altered by lactoferrin treatment.

Lactoferrin appears to reverse the tachypnea induced by RSV infection in mice. Since viral replication was not altered, the effect appears to be related to modulation of the immune response.

Sponsored by Abbott Laboratories.