Yoshiya Yoshida

Detection of rotavirus in faeces by latex agglutination

Human rotavirus (HRV) in faeces of patients may be readily detected with high sensitivity and specificity using latex agglutination (LA) on a glass slide by making use of the cross-reactivity of anti-calf rotavirus (CRV) antibody. Latex particles were coated with anti-CRV immunoglobin. The antibody coated particles (AC-L) are specifically agglutinated by both CRV and HRV, and the agglutination is evident macroscopically within a minute. To examine the sensitivity and reliability of the LA method compared to other methods, HRV in faecal extracts of 48 infants with acute gastroenteritis was sought by the LA, reversed passive haemagglutination (RPHA) and electron microscope (EM) methods. Samples positive by the EM method were all positive by the LA method, and samples negative by EM were all negative by LA. The LA method is suitable for application as a simple clinical diagnostic test.

Production and Characterization of Monoclonal Strain-Specific Antibodies against Prototype Strains of Rickettsia tsutsugamushi

We have developed 18 hybridoma cell lines which secrete murine monoclonal strain‐specific antibodies to prototype strains of Rickettsia tsutsugamushi: nine anti‐Gilliam, four anti‐Karp and five anti‐Kato antibodies. All the monoclonal antibodies reacted only with their homologous strains in direct and indirect immunofluorescence (IF), or indirect immunoperoxidase (IP) test. By IF and IP tests with the monoclonal antibodies, 22 strains of R. tsutsugamushi, which were newly isolated from mites, field rodents and patients with Tsutsugamushi disease (scrub typhus) in Japan, were all clearly identified as either Gilliam or Karp type. Analysis by polyacrylamide gel electrophoresis and immunoblotting techniques revealed that the monoclonal antibodies recognized primarily the polypeptides of an apparent molecular weight of 54 to 56 kilodaltons of the homologous rickettsial surface. The monoclonal antibodies produced in the present study should enhance the serotyping and further analytical investigation of the rickettsial antigens since they recognize the strain‐ or type‐specific polypeptides and do not show any cross‐reaction among strains.

Occurrence of high ratio of males after introduction of minocycline in a colony of leptotrombidium fletcheri infected with orientia tsutsugamushi

In colonies of Leptotrombidium fletcheri mites infected with Orientia tsutsugamushi (Ot), the agent of scrub typhus, males rarely appear. In the present study, the development of a high ratio of males was observed after introduction of minocycline (MC). A high dose of MC was injected subcutaneously into a mouse, and by feeding unfed larvae from an infected mite colony on this mouse, the Ot in the mites were successfully killed. Of a total of 130 unfed larvae attached to the mouse, 29 developed into females; of these, 9 laid an average of 112.4 eggs/female. Unfed larvae in the succeeding generations were attached to untreated mice. All adults in the P and F1 generations were females, and males started to appear at the F2 generation. The ratio of males to females was 332:7, 108:13, 263:61 and 71:9 at the F2, F3, F4 and F5 generations, respectively. These data suggest that Ot in the ovary or gonad may suppress the development of males.

[Characterization of anti-HBs antigen monoclonal antibodies and application to subtyping].

Several monoclonal antibodies were produced against purified HBs antigens, subtype adr adw and ayw. The subtype specificity of these nine antibodies was characterized by the passive hemagglutination inhibition method. The specificity of these anti-HBs monoclonal antibodies was analyzed with use of 31 HBs antigen panels. Five of the nine monoclonal antibodies had a specificity against the group a-determinant of HBs antigen. Two antibodies were demonstrated to have anti-r specificity and another two were anti-w.One of these anti-a monoclonal antibodies, in its reaction pattern, resembled anti-a polyclonal antibady derived from human serum. This anti-a monoclonal antibody was used as the standard to determine HBs antigen subtyping, The results nearly agree perfectly with results obtained when anti-a polyclonal antibodies were used as the standard.Using these monoclones, we analysed HBs antigen subtypes of asymptomatic carriers. Although the antigen titer changed at various time in each parson, the ratio of each subtype determinant was unchanged. However, three anti-a monoclonal antibodies showed a different reaction pattern against “a” determinant of individual carriers, and therefore “a” determinant of HBs antigen might be subdivided, and should be analyzed in more detail by monoclonal antibodies.