Isolation of the various serotypes of Mannheimia haemolytica and preparation of the first vaccine candidate in Iran.

BACKGROUND: Mannheimia haemolytica is one of the main agents of domestic pneumonic mannheimiosis, but a proper vaccine has not been explored in IRAN. METHODS AND RESULTS: 362 lung and nasal samples from sick domestic animal were detected by culture and PCR methods. Totally, 71 M. haemolytica isolates were identified in three main serotypes (A1, A2, and A6). Serotypes A2 (38/71; 54%) and A1 (25/71; 39%) were the most frequently detected, whereas the A6 serotype was detected with a frequency of less than 1% (1/71; 1%) and 7 isolates remained unknown (7/71; 10%). Subsequently, M. haemolytica vaccinal strain was developed and then formalin-killed vaccine was prepared. It provided the best protection against mannheimiosis in sheep which was proved by indirect ELISA. CONCLUSIONS: Our results suggest that the efficacy and safety of vaccine strain are remarkable and may serve as a new therapeutic target in mannheimiosis.

Tetranuclear rollover cyclometalated organoplatinum-rhenium compounds; C-I oxidative addition and C-C reductive elimination using a rollover cycloplatinated dimer.

The novel tetranuclear Pt(IV)-Re(VII) complex [Pt2Me4(OReO3)2(PMePh2)2(µ-bpy-2H)], 4, is synthesized through the reaction of silver perrhenate with a new rollover cycloplatinated(IV) complex [Pt2Me4I2(PMePh2)2(µ-bpy-2H)], 3. In complex 4, while 2,2'-bipyridine (bpy) acts as a linker between two Pt metal centers, oxygen acts as a mono-bridging atom between Pt and Re centers through an unsupported Pt(IV)-O-Re(VII) bridge. The precursor rollover cycloplatinated(IV) complex 3 is prepared by the MeI oxidative addition reaction of the rollover cycloplatinated(II) complex [Pt2Me2(PMePh2)2(µ-bpy-2H)], 2. Complex 2 shows a metal-to-ligand charge-transfer band in the visible region, which was used to investigate the kinetics and mechanism of its double MeI oxidative addition reaction. Based on the experimental findings, the classical SN2 mechanism was suggested for both steps and supported by computational studies. All complexes are fully characterized using multinuclear NMR spectroscopy and elemental analysis. Attempts to grow crystals of the rollover cycloplatinated(IV) dimer 3 yielded a new dimer rollover cyclometalated complex [Pt2I2(PMePh2)2(µ-bpy-2H)], 5, presumably from the C-C reductive elimination of ethane. The identity of complex 5 was confirmed by single crystal X-ray diffraction analysis.

Phosphorescent heterobimetallic complexes involving platinum(iv) and rhenium(vii) centers connected by an unsupported µ-oxido bridge.

Heterobimetallic compounds [(C^N)LMe2Pt(µ-O)ReO3] (C^N = ppy, L = PPh3, 2a; C^N = ppy, L = PMePh2, 2b; C^N = bhq, L = PPh3, 2c; C^N = bhq, L = PMePh2, 2d) containing a discrete unsupported Pt(iv)-O-Re(vii) bridge have been synthesized through a targeted synthesis route. The compounds have been prepared by a single-pot synthesis in which the Pt(iv) precursor [PtMe2I(C^N)L] complexes are allowed to react easily with AgReO4 in which the iodide ligand of the starting Pt(iv) complex is replaced by an ReO4- anion. In these Pt-O-Re complexes, the Pt(iv) centers have an octahedral geometry, completed by a cyclometalated bidentate ligand (C^N), two methyl groups and a phosphine ligand, while the Re(vii) centers have a tetrahedral geometry. Elemental analysis, single crystal X-ray diffraction analysis and multinuclear NMR spectroscopy are used to establish their identities. The new complexes exhibit phosphorescence emission in the solid and solution states at 298 and 77 K, which is an uncommon property of platinum complexes with an oxidation state of +4. According to DFT calculations, we found that this emission behavior in the new complexes originates from ligand centered 3LC (C^N) character with a slight amount of metal to ligand charge transfer (3MLCT). The solid-state emission data of the corresponding cycloplatinated(iv) precursor complexes [PtMe2I(C^N)L], 1a-1d, pointed out that the replacement of I- by an ReO4- anion helps enhancing the emission efficiency besides shifting the emission wavelengths.