Letters Section Editor: Robert M. Golub,
MD, Senior Editor.
In Reply: The concept of an interaction between
EBV and human endogenous retroviruses, including an MSRV, is interesting,
particularly given that herpesviruses such as EBV and human herpesvirus 6
(HHV-6) may trigger retroviral activation.1 The
human endogenous retrovirus type H (HERV-H) has also been associated with
MS.2 Combinations of the HERV-H and herpesvirus
antigens result in highly increased cellular immune responses, as measured
by blast transformation assays based on peripheral blood mononuclear cells
among both MS patients and healthy controls.3 However,
it is not clear how these viral interactions would explain the apparent protective
effect of younger infant siblings found in our study.
Dwyer T, Ponsonby A, van der Mei I, Blizzard L, Taylor B, Kemp A, Kilpatrick T. Exposure to Infant Siblings During Early Life and Risk of Multiple Sclerosis—Reply. JAMA. 2005;293(17):2089-2090. doi:10.1001/jama.293.17.2089-b