Table 2.

Viral isolation from nasal swabs taken from vaccinated and unvaccinated ponies after challenge with A/eq/Ohio/03 virus.

Group	N	Egga (No. ponies with positive results) b	Duration of shedding d (egg) a	EID50 (per mL)e	PCRf	Duration of shedding d (PCR)
Monovalent NS	4	1	2	-	3256	2.5
Monovalent NF	4	1	0.67	-	2491	1.67
Trivalent NF	3	0	0	-	2525	0.5
Control NF	4	4c	5	+ (0 – 1×104)	3.07×106	5.25

^avirus growth in embryonated eggs. Nasal swab samples (0.1ml, undiluted) were injected into allantoic cavities of each of three 10-day-old eggs. Following incubation, allantoic fluids were harvested and tested for virus by hemagglutination assay. If any one egg tested positive, the swab sample was called virus-positive and the pony from which it originated was counted as shedding virus on that day.

^bresults (positive or negative) are cumulative from days 2–5 post-challenge

^con day 2 post-challenge, only 2 of the 4 ponies were positive by HA assay. On all other days, all 4 ponies were positive.

^dmean number of days of virus shedding

^evalue on day 2 post-challenge

^fmean value on day 3 post-challenge (day of peak shedding in control group)

+ = influenza detected, − = influenza not detected