Population-specific evolution of HIV Gag epitopes in genetically diverged patients
Abstract
Background:
In the microbial ecosystem, microbes compete for space and nutrients. Consequently, some have
developed the ability to kill or inhibit the growth of other competing microbes by producing antimicrobial
substances. As the
‘producer’
species are generally immune to these substances, their compounds act on the
competing microbial species and give the producer more space and access to nutrients for growth. Many currently
used antibiotics were developed by exploiting this potential of certain microbes.
Findings:
Here, the free-living amoeba, Acanthamoeba castellanii
, was investigated for its antibacterial activity
against representative Gram positive and Gram negative bacteria, while bacterial isolates were tested for their
anti-amoebic properties. Conditioned medium from
A. castellanii
showed remarkable bactericidal properties against
methicillin-resistant
Staphylococcus aureus
(MRSA) exhibiting almost 100% kill rate, but had limited effect against
Acinetobacter
sp., Pseudomonas aeruginosa and vancomycin-resistant Enterococcus faecalis
(VRE). Similarly, the
conditioned medium of
E. coli K1 and Enterobacter
sp., exhibited potent anti-Acanthamoebic effects in a concentrationdependent
manner. Conditioned media of
Acanthamoeba, E. coli K1 and Enterobacter
sp. showed no cytotoxicity
in vitro
when tested against human brain microvascular endothelial cells. Active molecule/s in aforementioned amoebic
and two bacterial conditioned media were 5
–
10 kDa, and <5 kDa>respectively.
Conclusions:
A. castellanii
conditioned medium showed potent bactericidal properties against MRSA. The active
molecule(s) are heat- and pronase-resistant, and in the 5 to 10 kDa molecular mass range. Contrary to this,
E. coli
K1
and
Enterobacter
sp., conditioned medium showed anti-amoebic effects that are <5 kDa in molecular>mass, suggestive
of active metabolites.