Experimental dual infection of cesarean-derived, colostrum-deprived pigs with Mycoplasma hyopneumoniae and pseudorabies virus.
To determine whether pseudorabies virus (PRV) infection increases the severity of pneumonia by Mycoplasma hyopneumoniae, 18, 10-week-old Cesarean-derived, colostrum-deprived pigs were randomly assigned to 3 groups of 6 pigs each. Pigs in groups A and C were inoculated intranasally with M. hyopneumoniae at 10-week-old. At 11-week-old, pigs in groups B and C were inoculated intranasally with PRV. All pigs were initially seronegative for M. hyopneumoniae and PRV. Three pigs of each group were euthanized at 12-week-old, and remaining pigs at 14-week-old. At necropsy, gross lesions in the lung were observed in the pigs of groups A and C. On post-inoculation-week (PIW) 2 with M. hyopneumoniae (at 12-week-old), lung lesions were recognized in one of the 3 pigs in group A and all the pigs in group C. The mean percentage of the lung lesions were 0.1% in group A and 9.8% in group C. M. hyopneumoniae was isolated from broncho-alveolar lavage fluids (BALF) of pigs in group A with titer of 10(2) to 10(3) CCU/0.2 ml and in group C with titer of 10(5) to 10(6) CCU/0.2 ml. On PIW 4 (at 14-week-old), lung lesions were observed in all the pigs in groups A and C, and the mean percentage of the lung lesions were 8.3% in group A and 17.2% in group C. M. hyopneumoniae was isolated from BALF in group A with titer of 10(4) to 10(7) CCU/0.2 ml and in group C with titer of 10(6) to 10(7) CCU/0.2 ml. PRVs were isolated from nasal swab and tissue samples in groups B and C. After inoculation, antibody against M. hyopneumoniae was detected in groups A and C, and against PRV in groups B and C. Under the present experimental conditions, PRV infection appear to have effect on the severity of experimentally induced acute mycoplasmal pneumonia in young pigs.
Shibata
I
I
Zen-noh Institute of Animal Health, Chiba, Japan.
Okada
M
M
Urono
K
K
Samegai
Y
Y
Ono
M
M
Sakano
T
T
Sato
S
S
D000818:Animals; D001831:Body Temperature; D002585:Cesarean Section / Q000662:veterinary; D003126:Colostrum / Q000276:immunology*; D008168:Lung / Q000473:pathology; D009175:Mycoplasma Infections / Q000150:complications / Q000276:immunology / Q000503:physiopathology*; D011557:Pseudorabies / Q000150:complications / Q000276:immunology / Q000503:physiopathology*; D013552:Swine; D013997:Time Factors