Antigenic competition among different 'O' antigens of Salmonella enterica subspecies enterica serovars during hyperimmunization in pony mares.

The present study on antigenic competition among somatic 'O' antigens of different Salmonella groups (A, B, C1, C2, D and E1) in mares revealed that the immune response to most of the antigens was not (A, B, C2) or little (C1, D) affected by antigenic competition. However, E1 group antigen, which induced high antibody titres (Avg. 12967.3) when given alone, produced almost 3.5 log2 lower antibody titres on giving with other antigens, indicating the antigenic competition among some Salmonella group antigens. The antigenic competition varied for different antigens even of the similar chemical nature. Therefore, antigens belonging to different somatic groups should not be given together for the purpose of raising polyvalent serum or for immunization using multivalent Salmonella vaccines prepared from strains of different 'O' groups revealing antigenic competition.

Resistencia de diferentes sorogrupos de seratia marcescens ao soro humano normal e sua patogenicidade para camundongos / Serratia marcescens: studies on normal human serum resistance, serogrouping and pathogenicity for mice

Isolados nosocomiais de Serratia marcescens pertencentes a diferentes sorogrupos (01, 03, 04, 05, 010, 013, 016, 019 e 06,14) foram analisados quanto a resistencia à açäo bactericida do soro humano (HS). De 60amostras estudadas, 55 (91,6 por cento) foram HS-resistentes para uma concentraçäo de 50 (por cento) de soro e somente amostras do sorogrupo 06,14 foram HS-sensíveis. Todos os isolados de sangue, olhos e ossos foram resistentes ao HS. Amostras com diferentes sensibilidades ao HS foram testadas para a patogenicidade e todas foram letais para camundongos com a mesma DL50 (3,5 x 10(elevado a sétima potencia)). Esses resultados sugerem que a resistência ao soro näo é o principal determinante na virulência de S. marcescens.