This study was intended to establish the susceptibility of Madin and Darby Canine Kidney (MDCK) cells for the propagation of Hantaan virus and to evaluate the applicability of N4DC~K cell system for the measurement of fluorescent antibody titers in sera from patient with Hemor rhagic fever with renal syndrome (HFRS). Through the experiments, observations were made with development of`specific fluorescent antigen in MDCK cells f011owing inoculation with Hantaan virus, blocking of appearence of" such a specific fluorescent antigen in MDCK cells when Hantaan virus was pretreated either with convalescent patient´s Serum or immune rat serum, comparison of growth patterns of Hantaan virus in MDCK, A-549 and Vero F6 cells, demonstration of characteristic; 3 segments of single-stranded viral RNA in Hantaan virus inooulated MDCK cells and finally, applicability of MDCK cell system of the itration of fluorescent antibody in convalescent sera from patients with HFRS.
The results are summarized as follows:
L On 8 day after Hantaan virus inoculation, specific granular fluorescent antigens developed´, ex-elusively in the cytoplasm of´ MDCK cells when observed by the indirect fluorescent antibody technique. Such fluorescent antigens in MDCK cells were very much similar to those in both Vero E6 and A-549 cells inoculated with the same virus, except that the occurrence of nonspecific fluorescence was far less in MDCK cells.
2. Both the percentages of cells exhibiting specific fluorescence and the intensities of such fluorescence increased significantly through the first and second passage of MDCK cells inoculated with Hantaan virus.
3. Such development of virus-specific cytoplasmic fluorescent antigens in MDCK cells was specifically inhibited by the pretreatment of inoculating virus either with convalescent serum from patients I
with HFRS or with immune rat serum.
f 4. The growth pattern of Hantaan virus in MDCK cells was fairly similar to those in Vero E6 cells and A-549 cells. The infectivity titers measured during 2 weeks after virus inoculation were also
i comparable. The maximum titers attained were 103 to 10/0.3 ml levels.
5. Existence of viral single-stranded RNA in 3 segmented pieces in MDCK cells infected with Hantaan virus was demonstrated in this study. These three RNA segments in virus-infected MDCK
cells proved to be identical with the ones in infected Vero E6 cells.
6. Measurements of fluorescent antibody titers in the use of Hantaan virus infected MDCK cells resulted in the comparable titrations of convalescent sera from patients with HFRS´. The results of such titrations -~ti-ere in full agreement with those obtained W41th both A-549 cells and Verso E6 cells inoculted with Hantaan virus.
It was concluded that in addition to A-549 cells and Vero E6 cells, MDC´K cell culture proved to be susceptible and sensitive for the propagation of Hantaan virus.
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