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To determine the rabies antibody level of twenty-four hyperimmune equine sera, Standard Mouse Neutralization (SMN) and Couterimmunoelectrophoresis (CIE) tests were carried out, both at the Instituto Butantan (IB) and Instituto Panamericano de Proteccíon de Alimentos y Zoonosis (INPPAZ). Statistical analysis has shown a correlation (r) of 0.9317 between the SMN and CIE performed at the IB, while at the INPPAZ it scored 0.974. Comparison of CIE data of both laboratories yielded a correlation of 0.845. The CIE technique has shown to be a sensitive and efficient as the SMN in titrating antirabies hyperimmune equine sera. Based on CIE results, a simple, rapid and inexpensive technique, titers of sera antibody can be rellably estimated in SMN test.

Ten lots of Fuenzalida & Palacios type antirabies vaccine for human use, produced at the Instituto Butantan (São Paulo, Brazil) were stored at temperatures of 45, 37, 28 and 2-8 degrees C. The potency of each lot was determined in samples taken at varied time intervals using the NIH method and lots presenting antigenic values > or = 0,3 were considered satisfactory for use. After 2 hours at 45 degrees C the antigenic value of one out of 10 lots tested was found to be less than the minimum required value. At 37 degrees C all lots maintained satisfactory antigenic values until the third day of storage, whilst at 28 and 2-8 degrees C the potency was fully maintained, respectively for 10 and 360 days. At the ideal temperature of 2-8 degrees C, 100% of the tested vaccines maintained the minimum required antigenicity for a longer period (16 months) than the expiration time of 6-12 months usually recommended for this type of biological produced in Latin American and Caribbean countries. Thus, the obtained data suggested that in countries still producing Fuenzalida & Palacios type vaccine, the expiration tim could be extended to 16 months, what could prevent the unnecessary discarding of products still in useful condition.

The efficiency of the fluorescent antibody (FA) test in detecting rabies virus antigen in decomposed specimens was evaluated in simulated conditions of the safety test recommended for the assessment of residual virus in inactivated rabies vaccines. The CVS-infected mice were submitted to different treatments combining time and temperature in order to cause different stages of carcass decomposition and, the FA test was carried out sequentially at pre-determined time intervals. For the materials stored at 25 degrees C, greater difficulties for prompt recognition of the inclusion bodies were found after 12-18h, whilst the specimens maintained at 4 degrees C, the inclusions were easily visualized for up to 48h. Brain smears of carcasses kept at -20 degrees C were suitable for adequate identification after 720 h of storage. In carcasses that had been maintained at 25 degrees C for 10 h with additional storage at 4 or -20 degrees C, rabies antigenicity could not be detected, respectively after 10 and 24 h, due to tissue decomposition. The authors recommend that the FA test, when applied as an additional tool for the control of the safety test of inactivated rabies vaccine using mice, care must be taken in order to avoid the use of decomposed materials.

This study demonstrated that the antigens and indicator sera produced by the Butantan Institute may be employed with success in the counterimmunoelectrophoresis technique for the titration of rabies antibodies in sera from immunized individuals. No statistically significant differences were demonstrated between the results obtained in the standardization tests carried out at the Butantan Institute and the reference control tests performed at the Pan American Zoonoses Center. It is proposed that the Butantan Institute be in charge of the production and distribution of these reagents at the national level.

The present study evaluates the humoral and cellular immune responses in 35 volunteers submitted to short antirabies vaccination schedules with the Fuenzalida & Palacios vaccine based on the administration of doses on non consecutive days. The volunteers were divided into two groups. The first group received a total number of five doses given on days 0, 4, 7, 20 and 35. The other group received four doses, the first one being a double dose given on day 0 and than three other single doses on days 7, 20 and 35. The evaluation of humoral immune response was carried out by serum neutralization (SN) and indirect immunofluorescence (IIF) tests, while the cellular immune response was evaluated by lymphoblastic transformation assay (LTA) and skin test (ST). According to our results these reduced schedules elicited early and effective humoral and cellular immune responses to rabies antigen suggesting that new reduced schedules should be extensively studied in order to give the proper bases to the proposition of changes in the current long-term schedule.