title: Experimental dual infection of pigs with an H1N1 swine influenza virus (A/Sw/Hok/2/81) and Mycoplasma hyopneumoniae.
abstract: Dual infection of pigs with swine influenza virus (SIV) and Mycoplasma hyopneumoniae was carried out to compare the clinical and pathological effects of dual infection in caesarian derived and colostrums deprived (CDCD) pigs, with that of a single infection with M. hyopneumoniae. In Experiment 1, 40-day-old CDCD pigs were inoculated only with SIV (A/Sw/Hok/2/81, H1N1). The virus was isolated from nasal swabs for 5-6 days. None of these pigs showed clinical signs of infection throughout the experimental period. These results suggested that this strain can infect pigs but is only slightly pathogenic when it is inoculated singly to a CDCD pig. In Experiment 2, 60-day-old CDCD pigs were inoculated with M. hyopneumoniae and then were inoculated with SIV (A/Sw/Hok/2/81) at 1 week (MHYO-7d-SIV-7d group) or 3 weeks (MHYO-21d-SIV-7d group) after M. hyopneumoniae inoculation. Macroscopically, dark red-to-purple lung lesions were observed in all of pigs at 14 or 28 days post-inoculation. Percentages of dark red-to-purple lung lesions in dual infection groups (MHYO-7d-SIV-7d group: 18.7 +/- 4.2%, MHYO-21d-SIV-7d group: 23.0 +/- 8.0%) were significantly (P < 0.05) increased compared to those of each control group in which pigs were inoculated only with M. hyopneumoniae (MHYO-14d group: 4.7 +/- 2.9%, MHYO-28 group: 3.3 +/- 2.4%). Microscopically, bronchial epithelial lesions (epithelial disruption, degeneration, hyperplasia and formation of microabscess) were frequently observed in dark red-to-purple lung lesions of only the dual infection groups. These results demonstrate that the lung lesion of pigs inoculated with M. hyopneumoniae and SIV is more severe than that of pigs inoculated only with M. hyopneumoniae.
authors.affiliation: Zen-noh Institute of Animal Health, 7 Ohja-machi, Sakura, Chiba 285-0043, Japan. yazawas@zk.zennoh.or.jp
authors.forename: Shigeto
authors.initials: S
authors.lastname: Yazawa
authors.forename: Munenori
authors.initials: M
authors.lastname: Okada
authors.forename: Masaaki
authors.initials: M
authors.lastname: Ono
authors.forename: Seiichi
authors.initials: S
authors.lastname: Fujii
authors.forename: Yo
authors.initials: Y
authors.lastname: Okuda
authors.forename: Isao
authors.initials: I
authors.lastname: Shibata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kida
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001831:Body Temperature; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D005856:Germ-Free Life; D006385:Hemagglutination Inhibition Tests / Q000662:veterinary; D006651:Histocytochemistry / Q000662:veterinary; D053118:Influenza A Virus, H1N1 Subtype; D009980:Influenza A virus / Q000254:growth & development*; D008168:Lung / Q000382:microbiology / Q000473:pathology; D045705:Mycoplasma hyopneumoniae / Q000254:growth & development*; D009976:Orthomyxoviridae Infections / Q000378:metabolism / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D045729:Pneumonia of Swine, Mycoplasmal / Q000382:microbiology* / Q000821:virology*; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology* / Q000473:pathology / Q000821:virology*; D017201:Virus Shedding
chemical_list: D000914:Antibodies, Viral