A Comparative Study of the RAPINA and the Virus-Neutralizing Test (RFFIT) for the Estimation of Antirabies-Neutralizing Antibody Levels in Dog Samples.

The mass vaccination of dogs against rabies is a highly rational strategy for interrupting the natural transmission of urban rabies. According to the World Organization for Animal Health (OIE) and the World Health Organization (WHO), the immunization of at least 70% of the total dog population minimizes the risk of endemic rabies. Knowledge of the virus-neutralizing antibody (VNA) level against the rabies virus (RABV) is required to evaluate protective immunity and vaccine coverage of dogs in the field. The rapid focus fluorescent inhibition test (RFFIT) and the fluorescent antibody virus neutralization (FAVN) test are recommended by OIE and WHO to determine the VNA levels in serum. However, these tests are cell culture based and require the use of live viruses and specialized equipment. The rapid neutralizing antibody test (RAPINA) is a novel, immunochromatographic test that uses inactivated virus to estimate the VNA level qualitatively. It is a simple, rapid and inexpensive, although indirect, assay for the detection of VNA levels. The RAPINA has shown good positive and negative predictive values and a high concordance with the RFFIT results. In this study, we compared the performance of the two tests for evaluating the vaccination status of dogs in the Philippines, Thailand and Japan. A total of 1135 dog sera were analysed by the RAPINA and compared to the VNA levels determined by the RFFIT. The overall positive and negative predictive values of the RAPINA were 96.2-99.3% and 84.5-94.8%, respectively, with a concordance (kappa) of 0.946-0.97 among the three countries. The RAPINA results were highly homologous and reproducible among different laboratories. These results suggest that this test is appropriate to survey vaccination coverage in countries with limited resources.

Immunoglobulin G enzyme-linked immunosorbent assay using truncated nucleoproteins of Reston Ebola virus.

We developed an immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA), using partial recombinant nucleoproteins (rNP) of Reston Ebola virus (EBO-R) and Zaire Ebola virus (EBO-Z). We examined the reaction of 10 sera from cynomolgus macaques naturally infected with EBO-R to each of the partial rNP in the IgG ELISA. All the sera reacted to the C-terminal halves of the rNP of both EBO-R and EBO-Z. Most of the sera reacted to the RdeltaC (amino acid (aa) 360-739), and Rdelta6 (aa 451-551) and/or Rdelta8 (aa 631-739) at a higher dilution than to the corresponding truncated rNPs of EBO-Z. The results indicate that this IgG ELISA is useful for detecting EBO-R specific antibody, and may have a potential to discriminate EBO-R infection from other subtypes.

Epidemiology of Ebola (subtype Reston) virus in the Philippines, 1996.

Ebola (subtype Reston [EBO-R]) virus infection was detected in macaques imported into the United States from the Philippines in March 1996. Studies were initiated in the Philippines to identify the source of the virus among monkey-breeding and export facilities, to establish surveillance and testing, and to assess the risk and significance of EBO-R infections in humans who work in these facilities. Over a 5-month period, acutely infected animals were found at only one facility, as determined using Ebola antigen detection. Three of 1732 monkeys and 1 of 246 animal handlers tested had detectable antibodies; all were from the same facility, which was the source of infected monkeys imported to the United States. Virus transmission, which was facilitated by poor infection-control practices, continued for several months in one facility and was stopped only when the facility was depopulated. None of the 246 employees of the facilities or 4 contacts of previously antibody-positive individuals reported an Ebola-like illness. This investigation suggests that human EBO-R infection is rare.