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Thirty-six blood samples were collected randomly from puppies [18 puppies each from vaccinated (Group I) and unvaccinated (Group II) dam] brought to Immunization Unit, Madras Veterinary College Teaching Hospital, Chennai. The samples were subjected to functional antibody assay (RFFIT) to know the kinetics of maternal derived antibody (MDA) against rabies. The mean MDA titre in group I and II puppies were found as 1.07 ± 0.18 IU/mL and 0.30 ± 0.037 IU/mL respectively. The statistical analysis (Student “t” test) revealed a highly significant difference (P<0.01) between MDA of two groups. Thus, this study strongly suggests that the dogs less than three months of age in endemic regions needs to be immunized against rabies in view of maintaining the population immunity and to reduce the bioburden of rabies risk.
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Objective@#To disclose the effects of booster immunization of human diploid cell rabies vaccine (HDCV) after eight years of primary vaccination.@*Methods@#Sixty subjects who had participated the phase Ⅲ clinical trial of freeze-dried HDCV were selected and gaven booster immunization after eight years of primary vaccination. The side effects of booster immunization were observed. The serum before and after 14 days of booster immunization were collected and detected the rabies virus neutralizing antibody (RVNA) by rapid fluorescent focus inhibition test (RFFIT). The positive rate and geometric mean titer (GMT) of RVNA before and after booster immunization were made statistical analysis.@*Results@#Total 54 subjects finished the follow-up and RVNA detection. No sever side-effects were observed in 30 min or 15 days of follow-up after booster immunization. The positive rate of RVNA before and after booster immunization were 51.85% (28/54) and 96.30% (52/54). The GMT of RVNA before and after booster immunization were 1.42 IU/ml and 30.61 IU/ml.@*Conclusions@#The freeze-dried HDCV has good immune effects with one-dose of booster immunization after eight years of primary vaccination.
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Objective To establish a CVS-11 pseudovirus particles ( pp)-based assay for detec-tion of neutralizing antibody against rabies virus. Methods An improved rapid fluorescence focus inhibition test ( RFFIT) for detection of neutralizing antibody against rabies virus ( RVNA) was established based on the CVS-11 pseudovirus expressing a luciferase reporter gene. Forty-six human serum samples were analyzed with the improved RFFIT and the results were compared with those by using standard RFFIT. Moreover, the improved RFFIT was used to detect the titers of RVNA in 91 serum samples collected from pet dogs and pet-breeders in Beijing. Results The coincidence rate of the improved RFFIT and the standard RFFIT was 100% regarding to the analysis of 46 human serum samples and 5 negative reference serum samples. Moreo-ver, the RVNA titers of all serum samples obtained with CVS-11 pseudovirus-based assay showed a signifi-cant high correlation with those obtained with standard RFFIT (n=46, r=0. 94, P<0. 000 1). All of the 91 serum samples collected from pet dogs and pet-breeders in Beijing were positive for RVNA as indicated by the improved RFFIT with a mean titer of 33. 01 IU/ml. Conclusion We established an improved RFFIT based on the CVS-11 pp expressing luciferase reporter gene, which might be used as a reliable alternative RFFIT for measuring RVNA titer. Analysis of the 91 serum samples collected in Beijing with the improved RFFIT showed that all samples were positive for RVNA.
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Aims: To determine the presence of rabies virus neutralizing antibodies (rVNA) as well the potency of the rVNA in rabies occupational risk humans in Niger State of Nigeria. Study Design: Cross-sectional study. Place and Duration: Research was conducted at the Department of Veterinary Public Health, Ahmadu Bello University, Zaria, Nigeria and Rabies Unit, Centers for Disease Control and Prevention, CDC, Atlanta, USA, between May, 2012 and March, 2013 Materials and Methods: A total of 185 human volunteers were recruited from rabies risk occupational groups who filled a structured questionnaire on their previous bite history and vaccination status, between May and July, 2012. A 2 ml each of blood from volunteers was collected and centrifuged at 3000 rpm for 10 minutes and sera separated into pre-labeled vacutainers. Standard Rapid fluorescent focus inhibition test (RFFIT) was used to detect the presence of rVNA in the sera. Further end point titration of the rVNA positive human sera was conducted to determine the potency. Results: The results indicated that, detectable titre of rVNA was recorded in 16.4% (23 of 140) viable human sera screened. Although from the questionnaire survey, 21.7% (5 out of the 23 positives) responded to have been vaccinated over ten years prior. At least 3 of the respondents (1 dog butcher and 2 dog meat consumers) who responded not previously vaccinated had some neutralizing antibody titre range of 0.65 – 0.7 IU/ml which is above the minimum protective titre (0.5IU/ml) recommended by WHO. Similarly, 3 respondents (2 veterinarians and 1 animal health personnel) who responded to have been previously vaccinated (> 10 years earlier) yet had a high titre range of 0.5 – 5.4IU/ml. The highest specific rate for rVNA of 25% each was seen amongst the dog butchers and pet owners followed by hunters (20%) and dog meat consumers (14.8%). Up to 125 (67.6%) of the volunteers do consume dog meat with only 12 (9.6%) of them being dog butchers who source dogs for slaughter from households within and outside their territories. Conclusion: Although the WHO minimum protective titre of rVNA is 0.5 IU/ml, the presence of relatively high titres amongst these risk groups in this report is an indication of a serious public health threat. This study recommends the vaccination of rabies high risk groups and further screening of rabies occupational risk and non risk groups in the study area and Nigeria at large.
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The World Health Organization (WHO) standard assay for determining antibody level is the rapid fluorescent focus inhibition test (RFFIT) and is used to determine the degree of immunity after vaccination against rabies.To compare the difference in RFFIT results between the laboratories of The National Institute of Infectious Disease in Japan (NIID) and the Chinese Centre for Disease Control (CCDC) as well the influence of the choice of standard serum (STD) for the detection,the two laboratories detection methods were simultaneously manipulated by RFFIT.The reference serums used in NIID and the WHO standard serum used in CCDC were compared in the same RFFIT detection to determine the titer of four sera samples C1,S1,S2 and S4 in parallel,and the titers of the detected sera samples were calculated using the standard formula for neutralizing antibody titer.No significant difference was found in RFFIT methods from the two laboratories and the RFFIT testing procedures of the two laboratories have good consistency.However,different titers were obtained with the tentative internal standard serum (TI-STD) produced by adjusting to 2.0 IU of WHO standard serum in NIID and the WHO STD.The titer determined with the TI-STD was higher than that determined with WHO STD,This difference appears to be significant and requires further investigation.
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The chiropterans constitute 25% of the world's mammal fauna. Due to the destruction of their natural ecosystem, the vampire bats have moved from nature to artificial roosts closer to man and domestic animals. This phenomenon has happened particularly in rural areas. Rabies is a viral anthropozoonosis, 100% lethal, and vampire bats (Desmodus rotundus) represent an important role in its epidemiology. D. rotundus were captured at night with mesh nets in partnership with the Botucatu Defense Office and sent to the Zoonosis Diagnostic Service, at the School of Veterinary Medicine and Animal Husbandry, UNESP. Serum samples from 204 bats were analyzed by enzyme-linked immunosorbent assay (ELISA) and fluorescent antibody viral neutralization test (FAVN) for rabies antibody detection. The results showed 7.4% of sera with titers higher or equal to 0.5 U for rabies antibodies, which demonstrated viral flow circulation among the studied region. Data suggest a need for constant monitoring accomplished by epidemiological and sanitary measures.(AU)