Table I.

Concentrations of Porcine reproductive and respiratory syndrome virus (PRRSV) RNA detected in aerosol samples from pigs inoculated with PRRSV alone or after prior inoculation with Mycoplasma hyopneumoniae

	Concentration of PRRSV RNA (TCID50/mL)
Agent(s) inoculated; animal age (mo)	Peaka	Mean over sampling period	Standard deviation
PRRSV MN-30100
2	1.0	0.05	0.10
6	0.5	0.05	0.09
PRRSV MN-30100 + M. hyopneumoniae
2	0.1	0.007	0.01
6	2.0	0.005	0.02
PRRSV MN-184
2	35	0.6	1.7
6	5	0.2	0.3
PRRSV MN-184 + M. hyopneumoniae
2	1330	40	125
6	6	0.2	0.4

TCID₅₀/mL — median tissue culture dose per milliliter

^aFor an individual animal in each group