SOERIPTO* text Balai Penelitian Veteriner Prosiding Temu Ilmiah Nasional Bidang Veteriner 1996 7 The aim of this study is to determine the virulence of four is-mutants of Mycoplasma gallisepncum strains in 2 week-old chickens. Groups of five 2 week-old SPF CSIRO Hybrid White Leghorn chickens were inoculated intraabdominally either with 0.2 ml of MG cultures of 80083 Is-3, 80083 Is-11, 80083 Is-15, 80083 1s-21 or 80083L strains. The sixth group was inoculated with mycoplasma broth and used as controls. All the chickens were killed 2 weeks after inoculation and examined for air sac lesions and antibody responses. The results showed that chickens inoculated with ts-mutants or 80083L had air sac lesions except with ts-I I mutant. The control and inoculated chickens with 80083 ts-3 or 80083 t1-11 had no antibody responses, whereas chickens inoculated with 80083 Is•15, 80083 ts-21 or 80083L had antibody responses. It is concluded that Is-11 mutant is not virulence in 2 week-old chickens. SOERIPTO* VIRULENCE OF 4 ARTVET807 ARTVET807 241111 20241111093124 INLIS000000000018991 Converted from MARCXML to MODS version 3.5 using MARC21slim2MODS3-5.xsl (Revision 1.106 2014/12/19)