|BEHAVIOUR OF SOUTH INDIAN VARIANT OF M.TUBERCULOSIS
DURING EIGHT YEARS OF ANIMAL PASSAGE
|VK Challu, Sujatha Chandrasekaran, B Mahadev, Bharathi
Jones & R Rajalakshmi: Indian J TB 1993, 40, 191-94.
South Indian Variant strain of M.tuberculosis has
been found to be less virulent to guineapigs through various studies
from Madras and Bangalore. It was not known whether the low virulent
nature of the tubercle bacilli was a fixed character or a change
due to serial passages inside the body over a period of time. Hence,
a study was conducted to see the behaviour of low virulent tubercle
bacilli over a period of eight years during twenty passages in animals.
Ten low virulent cultures of M.tuberculosis isolated
from patients belonging to Bangalore area were injected intramuscularly
into guineapigs. The extent of lesions was assessed through Mitchison's
Virulence scoring method. Bacilli recovered from the spleen of these
guineapigs were passed into another set of animals and virulence
scored. Twenty serial passages were thus performed over a period
of eight years. The findings revealed that throughout the study
in all the passages, the south Indian Variant of M.tuberculosis
maintained its low virulent character.
|KEY WORDS: VIRULENCE, ANIMAL PASSAGE, M.TUBERCULOSIS.