RESUMO
Plectranthus barbatus also known by the synonym Coleus forskohlii it is called as forskohlii and Indian coleus. It is a tropical perennial herb belongs to the family Lamiaceae widely cultivated in India used as traditional medicinal crop. Its tuberous roots produce forskolin, an extract useful for pharmaceutical preparations and research in cell biology. The incidence of mosaic with dark and light green patches, mottling, leaf distortion and reduction growth was noticed in commercial cultivation of coleus. For identification of the virus, the infected leaf sample extract was mechanically inoculated to different hosts such as chilli, tobacco, tomato, cucumber, cowpea and Chenopodium amaranticolor. Host range studies revealed that the virus showed severe mosaic symptoms on Nicotiana spp. and Cucumis spp. The virus produced systemic and local lesion symptoms in a different host. The Leaf dip preparation of virus infected leaf extract was observed under an electron microscope showed the presence of isometric particles of 28 nm in size. The healthy and infected samples were tested using DAC-ELISA against antibodies of CMV, GBNV and TSV the infected samples showed strong positive reaction with 1.85 optical density to CMV antibodies indicated the presence of CMV. For molecular identification, total RNA was isolated and used for RT-PCR amplification using CMV specific primers. RT-PCR resulted in the positive amplification in virus infected samples but not from a healthy control. The complete genome of CMV RNA-1 consists of 3360 nucleotides (nt) encoding replicase gene of 807 amino acids (aa). The CMV RNA-2 was 2983 nt in length containing 2a (859 aa) encoding RNA dependent RNA polymerase protein and 2b encoding viral silencing suppressor (112 aa), while RNA-3 encoding 3a movement protein (280 aa) and coat protein (219 aa) was 2223 nt in length. Phylogenetic analyses of nucleotide sequences of coleus CMV isolate is closely related to subgroup IB than to subgroup IA or II with other CMV isolates. In recombination analysis, the recombination event occurs between the subgroups of I, II as well as IA and IB in RNA 1, RNA2 and RNA3 of coleus isolate with other CMV isolates. To best of our knowledge, this is the first report of CMV infection in coleus.
RESUMO
Robust and physiologically relevant infection models are required to investigate pharmacokinetic-pharmacodynamic (PK/PD) correlations for anti-tuberculosis agents at preclinical discovery. We have validated an inhalation-based rat infection model of tuberculosis harbouring mycobacteria in a replicating state, that is suitable for investigating pharmacokinetics and drug action of anti-tubercular agents. A reproducible and actively replicating lung infection was established in Wistar rats by inhalation of a series of graded inocula of Mycobacterium tuberculosis. Following an initial instillation of â¼10(5) log10 CFU/lung, M. tuberculosis grew logarithmically for the first 3 weeks, and then entered into a chronic phase with no net increase in pulmonary bacterial loads. Dose response of front-line anti-TB drugs was investigated following pharmacokinetic measurements in the plasma of infected rats. Rifampicin, Isoniazid, and Ethambutol dosed per orally exhibited bactericidality and good dose response with maximal effect of 5.66, 4.66, and 4.80 log10 CFU reductions in the lungs, respectively. In contrast, Pyrazinamide was merely bacteriostatic with 1.92 log10 CFU/lung reduction and did not reduce the bacterial burden beyond the initial bacterial loads present at beginning of treatment in spite of high Pyrazinamide blood levels. Rat infection model with actively replicating bacilli provides a physiologically distinct and pharmacologically relevant model that can be exploited to distinguish investigational compounds in to bacteriostatic or bactericidal scaffolds. We propose that this rat infection model though need more drug substance, can be used in early discovery settings to investigate pharmacology of novel anti-tubercular agents for the treatment of active pulmonary tuberculosis.