The virtual venture-backed company, built from Day One with a merger end point in mind, is starting to pop up here and there as a strategic option.

The latest is a Hillman Medical Ventures startup, CorBec Pharmaceuticals Inc. CorBec (Horsham, Penn.) is focusing on manipulating macrophage function using small molecule steroid analogs to treat autoimmune disorders, infections associated with lung and kidney disease, atherosclerosis, and asthma and allergic disorders.

Macrophages recognize undesirable particles such as bacteria that have been coated with antibodies by the immune system. Cell surface receptors on macrophages, such as Fc gamma, attach to these immune complexes and dispose of them.

Hillman has been wrestling with the question of the appropriate model for startups ever since founding GenVec, a gene therapy company, in 1993, according to partner Hal Broderson. Broderson is president and CEO of CorBec.

'Virtual model