Songsri Kasempimolporn

Reduced-dose intradermal vaccination against hepatitis A with an aluminum-free vaccine is immunogenic and can lower costs.

A reduced dose (0.1 mL) of intradermal hepatitis A virus (HAV) vaccine could facilitate the control of hepatitis A in countries of endemicity. All study subjects receiving an aluminum-free HAV vaccine intradermally were seroprotected 28 days after vaccination (anti-HAV titer, > or =10 mIU/mL). Seroprotection rates decreased to 80.8% at 12 months but returned to 100%, with titers increasing 28-fold, after receipt of a booster vaccination.

Evaluation of a rapid immunochromatographic test strip for detection of Rabies virus in dog saliva samples.

An immunochromatographic test strip for Rabies virus was evaluated with dog saliva samples. The test was initially validated against 237 dogs of known infection status, and then evaluated in the field with 1,290 live dogs. By validation of paired saliva–brain specimens obtained from dogs at necropsy, the saliva strip test was 94.4% specific and 93.0% sensitive when compared to the gold standard fluorescent antibody test (FAT) on brain smears. The sensitivity and specificity of a nested polymerase chain reaction (nPCR) assay using saliva were 100% compared to the FAT results. The performance of strip test with field saliva samples from street dogs had a specificity of 98.7% in comparison to nPCR as the reference method. As the strip test kit can potentially be used outside the laboratory and be applicable as an on-site testing assay, it represents a powerful screening tool for epidemiological surveys and disease control. The test could be useful for the surveillance of rabies in dogs and, in particular, be used to monitor the success of rabies control programs.

Genetic Typing of Feline Rabies Virus Isolated in Greater Bangkok, Thailand

To study the molecular epidemiology of rabies virus that is prevalent among cats in greater Bangkok, Thailand, a total of 17 rabies virus isolates from cats were characterized and compared with 120 rabies virus isolates from dogs. Analyses were performed on the genetic polymorphism in the rabies virus nucleoprotein (N) gene. Rabies virus N gene of isolates was amplified by reverse transcription‐polymerase chain reaction. The diversity of N gene was revealed by the restriction fragment length polymorphism (RFLP) method. The rabies virus isolates from cats could be classified into 5 types, designated as Dd I‐Hf I, Dd II‐Hf II, Dd III‐Hf I, Dd IV‐Hf I, and Dd IV‐Hf III. Type Dd I‐Hf I was encountered more frequently than the others. It was apparent that no less than five rabies virus types presented in the areas of Bangkok. Moreover, all five RFLP patterns were typical of those which had been observed in dogs. Our findings suggest that there had been viral transmission between the dogs and the cats.

Demonstration of Rabies Virus Antigens by an Immunochromatographic Strip Test

An immunochromatographic strip test is designed for fast and easy detection of rabies virus (RABV) antigens in clinical samples. In the field, saliva is a preferred clinical sample in the living patient because quick detection in such samples may be ideal for allowing management to be implemented in real time. Although the absolute RABV concentration in saliva samples is not known, the strip test in a lateral flow format performs well enough to be used for the detection of RABV in dog samples. The strip test has an advantage over many other field diagnostic techniques in that the test procedure is simple, rapid, and can be performed by public health professionals as well as veterinarians. However, a negative result with the test strip may indicate the absence of RABV antigens or that antigens are present below the level of detection. Thus, it must be understood that a negative test does not exclude a diagnosis of rabies.

Demonstration of Rabies Antibody by a Latex Agglutination Test

A simple latex agglutination test (LAT) has been developed for determining rabies virus (RABV) antibodies in human and equine sera. The test is based on the capability of specific antibodies to agglutinate antigen- sensitized polystyrene latex beads. The LAT for determination of RABV antibodies can be performed using inactivated whole RABV, glycoprotein, or vaccine as a coupling antigen. The degree of agglutination could be scored as 4+, 3+, 2+, 1+depending on the size of agglutinated particles. Results of LAT are directly correlated with the rapid fluorescent focus inhibition test (RFFIT). There is a good correlation between the degree of agglutination scored in the LAT and the RFFIT titers, although it is not known whether results of LAT represent the detection of neutralizing antibodies. The LAT has the advantage of being rapid, simple to perform, easy to interpret, and applicable as an on-site testing tool for the estimation of RABV antibodies.

Demonstration of Rabies Virus Antigens by a Latex Agglutination Test

A simple and rapid latex agglutination test (LAT) has been developed for detecting rabies virus (RABV) antigens in saliva. Latex particles are coated with anti-rabies antibody. The antibody-coated particles are specifically agglutinated by RABV, and the agglutination is evident macroscopically within minutes. Because the antigens can be visualized easily, the test can be carried out in laboratories that do not have the necessary equipment for polymerase chain reaction (PCR). The assay might be used to rapidly screen animals suspected of having rabies infection, and in situations where facilities or resources to perform more complicated tests are not available. Saliva samples offer fewer occupational and disposal risks. However, the sensitivity of LAT using saliva might depend on the stage of disease at the time of sample collection. A negative result does not necessarily rule out the infection.