The regulation mechanism of interferon (IFN) and IFN-stimulated genes is a very complex procedure and is dependent on cell types and virus species. We observed molecular changes related to anti-viral responses in endothelial cells during Hantaan virus (HTNV) infection. We found that there are two patterns of gene expression, the first pattern of gene expression being characterized by early induction and short action, as in that of type I IFNs,' and the other being characterized by delayed induction and long duration, as those of IRF-7, MxA, and TAP-1/2. Even though there are significant differences in their induction folds, we found that all of IFN-α/β, IRF-3/7, MxA, and TAP-1/2 mRNA expressions reached the peak when the viral replication was most active, which took place 3 days of post infection (d.p.i.). In addition, an interesting phenomenon was observed; only one gene was highly expressed in paired genes such as IFN-α/β (3/277-folds), IRF-3/7 (2.2/29.4-folds), and TAP-1/2 (26.2/6.1-folds). Therefore, IFN-β, IRF-7, and TAP-1 seem to be more important for the anti-viral response in HTNV infection. MxA was increased to 296-folds at 3 d.p.i. and kept continuing 207-folds until 7 d.p.i.. The above results indicate that IFN-β works for an early anti-viral response, while IRF7, MxA, and TAP-1 work for prolonged anti-viral response in HTNV infection.

Chemokine KC has been considered to be a murine homologue of human GRO/MGSA and was identified as chemoattractant for monocytes and neutrophils. This study examined the expression of KC mRNA in thioglycollate-elicited mouse peritoneal macrophages that were stimulated in vitro with Candida albicans (CA). Also examined were the inhibitory effects of IL-10 on the CA-induced expression of KC gene by Northern blot analysis. CA was found to induce chemokine gene expression in a gene-specific manner, CXC chemokine IP-10 mRNA expression was not detected in CA-stimulated macrophages. Maximum KC mRNA expression was observed approximately 2 hr after adding CA. The inhibitory action of IL-10 to CA-induced KC mRNA expression on mouse peritoneal macrophages was independent on concentration and stimulation time of IL-10 and was observed approximately one hour after adding IL-10 and CA simultaneously. IL-10 produced a decrease in the stability of KC mRNA, and CA-stimulated macrophages with cycloheximide blocked the suppressive effect of IL-10. These results suggest that CA also induces chemokine KC from macrophages, and IL-10 acts to destabilize CA-induced KC mRNA and de novo synthesis of an intermediate protein is a part of the IL-10 suppressive mechanism.

Arbitrarily primed polymerase chain reaction (AP-PCR) method was applied to the differentiation of clinical isolates of M. tuberculosis strains. The primer which is specific to human papilloma virus (HPV) type 18 was found to be appropriate for the AP-PCR-based differentiation of M. tuberculosis isolates, since AP-PCR produced multiple polymorphic DNA bands when M. tuberculosis DNA was used as template. AP-PCR was performed using either one of the HPV type 18 primer and IS6110-specific primer (half-specific PCR, HS-PCR) or HPV type 18 primer pair only (nonspecific PCR, NS-PCR). The usefulness of these two methods in differentiating M. tuberculosis isolates, was measured by calculating dissimilarity values of 16 isolates using Cluster Analysis software. The highest dissimilarity values by HS-PCR and NS-PCR methods were 0.38 and 0.59, respectively. This suggested that NS-PCR method is better than HS-PCR method in strain differentiation. Although the dissimilarity value calculated by Cluster analysis of the standard restriction fragment length polymorphism method, in which IS6110 was used as a probe, was much more higher than the NS-PCR method, NS-PCR method using HPV 18 primers was quite useful for the differentiation of M. tuberculosis strains due to its rapidity and simplicity.

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