Possible Role of <i>Streptococcus pyogenes</i> in Mucocutaneous Lymph Node Syndrome VII. A Weak Response to Epstein‐Barr Viral Capsid Antigen in Mice Infected Neonatally with <i>S. pyogenes</i>

<jats:title>Abstract</jats:title><jats:p>A negligible, if not entirely negative, production of antibody to Epstein‐Bart virus(EBV)‐associated antigens in patients with mucocutaneous lymph node syndrome(MCLS) has been a perplexing problem for investigators who are in favor of a streptococcal etiology of the disease.</jats:p><jats:p>In the present investigations, antibody formation to EB viral capsid antigen (VCA) was assessed by the use of the indirect immunofluorescence technique in mice which had been subjected to neonatal infection with an attenuated strain of <jats:italic>Streprococcus pyogenes</jats:italic> or inoculation with either heat‐killed streptococci or streptolysin‐O, both of which were emulsified in Freund's complete adjuvant (FCA).</jats:p><jats:p>Each mouse of these groups was inoculated 30 days or so later with EBV dilution in FCA, blood was collected about three weeks after virus infection, and antibody titers were assessed individually.</jats:p><jats:p>According to the results of these experiments, no apparent difference was detected among the mice, irrespective of the methods of their neonatal treatment concerning their refractoriness to EB‐VCA; the majority of the animals showed titers of less than 1:8, no case having a titer above 1:30. In contrast, all sera from control mice yielded positive responses showing antibody titers of 1:250 and over.</jats:p><jats:p>Such an immunological character is an exact counterpart of that of MCLS patients. Accordingly, the recent research focus on EBV as a possible etiological agent of MCLS seems to be too restrictive.</jats:p>