Selecting and growing a potent biological agent, maintaining its virulence, making the germs hardy enough and stable enough for widespread dissemination and finding an efficient means of spreading them around all pose obstacles that have frustrated even well-financed state weapons programs.
Subsequently, two daughter strains were identified of which H37Rv maintained its virulence whereas H37Ra did not.
Steenken and Gardner [3] described the media used at Trudeau during the time, until 1922, in which the isolate maintained its virulence for rabbits and guinea pigs.
However, in iNOS-deficient mice, the mutant strain maintained its virulence [ 15].
At the same time, one can also question whether the non-inclusion of the tourniquet test resulted in inclusion of DHF I cases into the DF category or is it that DENV still maintains its moderate virulence in India in an endemic situation.
This fungus maintains its normal virulence after deletion of the gene that encodes a nonribosomal peptide synthase of the gliotoxin biosynthetic cluster, gliP, in neutropenic mice immunosuppressed with a combination of cyclophosphamide and corticosteroids.
In agreement with two recent studies, none of genes coding for known virulence factors were found to be lost in the Finnish strains [24], [25], suggesting that virulence factors are critical for B. pertussis to maintain its capability in the transmission and pathogenesis among the human populations.
The ability of C. albicans to adapt to and change its virulence in immunocompromised hosts can be a strategy of this organism to maintain its host alive and prolong its own survival.
Will the U.S. maintain its sobriety?
