In the given context, "VH/VHH" refers to two different types of antibody fragments derived from human sources.

"VH" stands for "variable heavy chain," which is a component of an antibody. Antibodies are composed of two heavy chains and two light chains. The variable heavy chain is responsible for binding to specific antigens, such as pathogens or foreign substances.

"VHH" stands for "variable domain of heavy chain-only," also known as a "nanobody." Nanobodies are a type of antibody fragment derived from camelid antibodies, such as llamas or camels. They consist of a single domain derived from the heavy chain, unlike conventional antibodies that have both heavy and light chains. Nanobodies are known for their smaller size and unique properties, which make them valuable tools in research and therapeutic applications.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4983233/
https://www.frontiersin.org/articles/10.3389/fimmu.2017.0160...
https://biomarkerres.biomedcentral.com/articles/10.1186/s403...
https://www.azolifesciences.com/article/VHH-Antibodies-(Nano...