Short duration of neutralizing antibody titers after pre-exposure rabies vaccination with suckling mouse brain vaccine

The human anti-rabies pre-exposure treatment currently used in Brazil, employing a 1-ml dose of suckling mouse brain vaccine (SMBV) administered on days 0, 2, 4 and 28, was compared to an alternative treatment with two 1 ml-doses on day 0, and one 1 ml-dose injected on days 7 and 21. The latter induced higher virus-neutralizing antibody (VNA) titers on day 21. Both Brazilian rabies vaccines produced with PV or CVS rabies virus strains were tested. Two additional volunteer vaccinee groups, receiving the pre-exposure and the abbreviated post-exposure schedules recommended by the WHO using cell-culture vaccine (CCV) produced with PM rabies virus strain, were included as reference. The VNA were measured against both PV and CVS strains on days 21, 42 and 180 by the cell-culture neutralization microtest. The PV-SMBV elicited higher seroconversion rates and VNA by day 21 than the CVS-SMBV. Both, however, failed to induce a long-term immunity, since VNA titers were <0.5 IU/ml on day 180, regardless of the schedule used. Cell-culture vaccine always elicited very high VNA on all days of collection. When serum samples from people receiving mouse brain tissue were titrated against the PV and CVS strains, the VNA obtained were similar, regardless of the vaccinal strain and the virus used in the neutralization test. These results contrast with those obtained with sera from people receiving PM-CCV, whose VNA were significantly higher when tested against the CVS strain.

Reduced schedule of human anti-rabies immunization with Fuenzalida & Palacios vaccine. Additional data

It was reevaluated a reduced schedule for anti-rabies post-exposure immunization with newborn mice nervous tissue vaccine (Fuenzalida & Palacios) in a group of 30 non exposed volunteers. The vaccine was administered by intramuscular injections on days zero, 2, 4, 16 and 27, in the deltoid area. Antibody levels were determinated by a simplified serum neutralization microtest on days zero, 16 and 37. On days 16 and 37 the antibody levels of the whole group was > or = 0.5 IU/ml and > or = 1.0 IU/ml, respectively. The cell mediated immunity was precociously detected (on day 4) by the delayed type hypersensitivity skin test. Our results show that this reduced schedule elicited an early and effective humoral and cellular immune response. However it is necessary other studies with larger groups of vaccinees in order to obtain definitive conclusion.

Simplified fluorescent inhibition microtest for the titration of rabies neutralizing antibodies

A simplified fluorescence inhibition microtest (SFIMT) was standardized for the evaluation of antirabies serum neutralizing antibodies based on the rapid fluorescent focus inhibition test (RFFIT) and the fluorescence inhibition microtest (FIMT). The simplified test showed reproducibility similar to that of the FIMT with advantages as easier executation and quicker reading. A simple pre-treatment of Brazilian microplates produced for immune enzymatic assays (PROSIL) gave equivalent results and substantial coast reduction, in relation to imported plates (DIFCO). The simplified test can be easily implemented in less sophisticated laboratories, as alternative to the mouse serum neutralization test, still the most largely employed in Brazil, or even to others as RFFIT and FIMT.

Detection of classic and invasive E.coli and Shigella serotypes in stools by indirect immunofluorescence.

A imunofluorescencia indireta (IFI) de sorotipos enteropatogenicos classicos e invasores de E. coli e de Shigella foi comparada com os metodos tradicionais de coprocultura e soroaglutinacao. Os resultados da IFI concordaram com os da coprocultura em 128 dos 140 casos testados para E.coli enteropatogenica (91%) e em 108 dos 112 testados para Shigella (96%). Todos os casos com reacoes positivas por coprocultura foram confirmados por IFI. No grupo controle, onde nao haviam sido isolados tais patogenos por coprocultura, foram evidenciados por IFI, 12 casos com reacoes positivas para E. coli enteropatogenica e 4 para Shigella, incluindo-se 2 com infeccao mista: E. coli 026/Sh. dysenteriae e E. coli 0124/Sh. dysenteriae. Foi discutida a alta sensibilidade e especificidade da IFI quando comparada aos metodos tradicionais, sendo sugerido o valor desta tecnica em estudos epidemiologicos envolvendo os microrganismos em questao e sua importancia no estabelecimento de diagnostico precoce na diarreia infantil aguda