The use of protein A‐sandwich ELISA as a means for quantifying serological relationships between members of the tobamovirus group

SUMMARY Indirect protein A sandwich ELISA (PAS‐ELISA) was used to determine the serological relationship between eight tobamoviruses with antisera to 26 viruses and virus strains within the group. Very distant relationships were determined by trapping virus with heterologous antiserum and detecting it with homologous antiserum, while near and close relationships were differentiated by using heterologous antiserum each time. The results were esssentially consistent with previously recorded relationships determined by tube precipitin and other serological tests. Since PAS‐ELISA requires much less antiserum than many conventional tests and does not require the purification of IgG or virus, it may offer many advantages in the detection of serological relationships.