Arthropod-borne virus antibodies in sera from residents of South-East Asia

Abstract
1. 1) Sera from indigenous residents of the Federation of Malaya, North Vietnam and Thailand were tested for neutralizing antibodies against numerous arthropod-borne viruses. 2. 2) The majority of the adult Malayans tested possessed antibodies against JE, Ntaya, Zika and MVE viruses. Many sera contained antibodies against WN, Ilhéus, Semliki Forest and RSSE viruses. Antibodies against 12 other arthropod-borne viruses were rarely encountered, or were absent from the Malayan sera tested. 3. 3) Studies on the age distribution of persons with antibodies against five of the viruses, revealed that nearly 90 per cent. of the indigenous Malayans studied possessed JE and Ntaya virus antibodies by late adolescence. Antibodies neutralizing Zika, Ilhéus and Semliki Forest viruses did not reach peak incidence (40 to 70 per cent.) until the fourth decade of life. 4. 4) Many sera from adult Malayans contained neutralizing antibodies to several arthropod-borne viruses, (JE, Ntaya, Zika, Ilhéus); whereas, the incidence of such reactors was significantly lower among children. A small percentage of sera from children neutralized but a single virus (JE, Ntaya or Zika). 5. 5) Most of the sera from 50 adult residents of Thailand contained JE, Ntaya, Semliki Forest and WN virus antibodies, while sera of only a few neutralized Zika and Ilhéus viruses. 6. 6) The antibody pattern of the Tonkinese of North Vietnam was similar to that of the Thais.