Arch Virol (2006) 151: 209–215
Possible association between phages, Hoc protein,
and the immune system
K. D browska
, A. Opolski
, and A. G´orski
Institute of Immunology and Experimental Therapy,
Polish Academy of Sciences, Wroclaw, Poland
Jan Dlugosz Academy, Czestochowa, Poland
Institute of Transplantology, Medical University of Warsaw, Warsaw, Poland
Received June 29, 2005; accepted August 19, 2005
Published online September 30, 2005
Summary. Mammals have become “an environment” for enterobacterial phage
life cycles. Therefore it could be expected that bacteriophages adapt to them. This
adaptation must comprise bacteriophage proteins.
Gp Hoc seems to have signiﬁcance neither for phage particle structure nor for
phage antibacterial activity. It is evidently not necessary for the “typical” anti-
bacterial actions of bacteriophages. But the rules of evolution make it improbable
that gp Hoc really has no function, and non-essential genes of T4-type phages
are probably important for phages’ adaptation to their particular lifestyle. More
interesting is the eukaryotic origin of gp Hoc: a resemblance to immunoglobulin-
like proteins that reﬂects their evolutionary relation. Substantial differences in
biological activity between T4 and a mutant that lacks gp Hoc were observed in
a mammalian system. Hoc protein seems to be one of the molecules predicted to
interact with mammalian organisms and/or modulate these interactions.
Bacteriophages are the most numerous entities in the biosphere. Their evolutionary
pathway is very complex and couples with the evolution of bacteria and eukaryotic
organisms. Their role in horizontal genetic transfer substantially inﬂuences the
development of the biosphere. On the other hand, phage evolution is specially
dynamic and intense [3, 9].
One of the most widespread groups of bacteriophages is the T4 family.
T4 itself is a kind of “guinea pig” in microbiology and molecular biology. It