Comparison of small hepatitis B surface antigen particles and human serum low density lipoprotein molecules by electron microscopy.

The small spherical particles associated with hepatitis B surface antigen (HBsAg) could be distinguished from the low density lipoprotein (LDL) molecules in human serum by examination of coded, negatively stained preparations. The HBsAg associated particles showed a more marked contrast against the background than LDL. Addition of specific antiserum to LDL caused a significantly reduced mean diameter of LDL molecules. An insignificant reduction in size of HBsAg particles was found by corresponding treatment. It is suggested that the antibody molecules protect LDL molecules protect LDL molecules against artificial flattening during preparation.