posted on 2022-01-11, 22:03authored byZhongkai Lu, Zhicheng Liu, Xia Li, Xinfang Qin, Haofei Hong, Zhifang Zhou, Roland J. Pieters, Jie Shi, Zhimeng Wu
Currently,
no specific therapeutics are available for foodborne
Shiga toxin-producing Escherichia coli (STEC) infections
that cause severe gastroenteritis and life-threatening complications
of hemolytic uremic syndrome (HUS). As STEC attachment to intestinal
epithelium might increase the host absorption of Shiga toxins and
severity of the disease, we were inspired to develop a bispecific
neutralizer capable of blocking its Shiga toxin and adhesin intimin
simultaneously. Two nanobodies against the B subunit of Shiga toxin
2 (Stx2B) and the C terminus of Intimin (IntC280) were genetically
fused together as the bispecific neutralizer, and it can be efficiently
produced in a conventional E. coli expression
system. We demonstrated that each of the nanobody modules in the bispecific
format showed increased antigen binding capability and was able to
functionally neutralize the binding of Stx2B or IntC280 to the respective
host receptors even in the presence of the two virulence factors together.
Moreover, the bispecific neutralizer was relatively stable to harsh
storage conditions and gastrointestinal pH extremes. Taking into account
its easy and economical production and superior pharmaceutical properties,
we believe that a nanobody-based bispecific neutralizer would be more
favorable and practical to be developed as a therapeutic to fight
STEC in the developing world.