Kruavon Balachandra

Cross-reactive Immunity among Different Serotypes of Virus Causing Haemorrhagic Fever with Renal Syndrome

Spleen cells primed by Prospect Hill (PH) or Puumala (Pu) virus could cross-react with Hantaan virus (HV) 76-118 strain-infected target cells after in vitro stimulation with HV-infected cells, although anti-PH or anti-Pu immune serum showed no cross-reactive neutralizing (NT) activity to HV without complement. These results and our previous findings with cross-reactive cytotoxic T lymphocytes (CTLs) suggest that some epitopes recognized by CTLs might be common among the hantavirus genus, while the epitopes related to NT activity were mainly specific to each virus of this genus. Next, to evaluate the cross-reactive immunities demonstrated by in vitro study, we investigated the effect of transferring T lymphocytes and sera from BALB/c mice immunized with PH or Pu virus into nude mice before HV inoculation. Transferring T lymphocytes primed by PH or Pu virus reduced HV titres in lungs and spleens of nude mice, corresponding with the results of the in vitro CTL assays. Transferring anti-Pu immune serum also decreased HV titres in nude mice, which seemed to reflect complement-dependent NT activity. Moreover ICR mice previously immunized with PH or Pu virus showed resistance to challenge with a lethal dose of the HV KHF strain, indicating that cross-reactive immunity induced by PH or Pu virus could protect ICR mice against pathogenic HV infection.

Prevalence of Antibody to Human Herpesvirus 6 in Women and Children

The antibody prevalence to human herpesvirus 6 (HHV‐6) was compared between pregnant women and control women of similar ages in Thailand. No significant difference was detected in the antibody positive rate and antibody titers between both groups. The antibody titers in sera collected from pregnant women at 1st and 3rd trimester remained unchanged. Next, the antibody prevalence in infants were examined and the positive rate decreased until 3 months and started to increase from 6 months after birth. The present results suggest that the reactivation of HHV‐6 might not occur during pregnancy and this virus infects infants postnatally.

Chapter 12 Exanthem subitum and HHV-6 infection

Publisher Summary Exanthem subitum or roseola infantum is a common disease in infants, characterized by high fever for a few days and the appearance of rash coinciding with subsidence of fever. It has been believed that a virus causes this disease because of evidences of the long incubation time, the leukopenia, the failure to respond to antimicrobial agents, and the failure to recover bacteria from the various body fluids. However, attempts to isolate the causative agents have been unsuccessful. This chapter illustrates that HHV-6 is the causal agent of exanthema subitum. This chapter also gives a walkthrough that HHV-6 causes exanthem subitum and this virus may have a cellular tropism of CD4+ lymphocyte. The airborne route may be suggested as a mode of transmission of HHV-6 infection.