"This cow antibody structure is just so unusual that we think it could be used to develop antibodies against targets that are relatively difficult for standard antibodies that normally would come from a human," Smider said.

Antibodies form a Y shape; at the ends of the two arms are loops of protein that latch onto the molecular target, called an antigen. These loops are called complementarity-determining regions, or CDRs. These regions can occur in astronomical numbers of configurations. When one configuration complements the structure of an antigen and fits, the immune system makes more of these antibodies.

An antibody region called CDR H3 is far longer in cows than in humans, which provides a greater reach to find the right molecular complement, such as in a deep indentation. A human antibody that neutralizes a broad range of HIV strains has an exceptionally long CDR H3 region, but is still much shorter than that in cows, the paper said.