Rapid diagnosis of pertussis using the Chinese hamster ovary cell cytotoxicity assay.
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Animals↗
Biomedical subjects
A Kasina
Publications and source records attributed to A Kasina.
Prolonged survival of Bordetella pertussis in a simple buffer after nasopharyngeal secretion aspiration.
A simple method for recovery of Bordetella pertussis is described using phosphate-buffered saline containing a casein hydrolysate for transporting secretions collected by nasopharyngeal aspirate. Bordetella pertussis was reisolated from 92% of clinical specimens held at 4 degrees C for 1 week and from all specimens held at -20 degrees C. This method will facilitate the centralization of laboratory facilities for the diagnosis of pertussis.
Bacteriological Techniques↗
Epitope specificity of three anti-pertussis toxin monoclonal antibodies with dissimilar effects in assays of toxin neutralizing activity.
The epitope specificity of two monoclonal antibodies against the S1 subunit (A4, A12) and one MAb against the S3 subunit (B9) of pertussis toxin, all protective in the mouse aerosol model of B. pertussis infection, but with different effects in assays of toxin-neutralizing activity, was examined in competitive binding enzyme immunoassays using biotinylated anti-pertussis toxin monoclonal antibodies or biotinylated goat anti-pertussis toxin polyclonal antibody after preincubation with unlabelled antibody. Biotinylated A4 was blocked by A4, A12, and B9; A12 was blocked by A4, A12, and B9. In contrast, biotinylated B9 was blocked by B9 and A4, but not by A12. All three monoclonal antibodies successfully blocked the anti-pertussis toxin polyclonal antibody; a mixture of the three anti-pertussis toxin monoclonal antibodies was more effective than any monoclonal antibody alone P less than or equal to 0.01). These data suggest that these three anti-pertussis toxin monoclonal antibodies recognize separate, but closely linked epitopes on pertussis toxin, and that epitopes on the S1 subunit and B-oligomer may induce protective immunity.
Animals↗
Modulation of Bordetella pertussis infection with monoclonal antibodies to pertussis toxin.
Three monoclonal antibodies to pertussis toxin were characterized and used to investigate its role in immunity. Antibody affinity correlated with toxin neutralization in in vivo and in vitro assays but was not the only determinant of protection against Bordetella pertussis infection. B9, a high-affinity anti-S3 antibody, was the most effective in neutralizing toxin-induced CHO cell clustering and hemagglutination in vitro and lymphocytosis and histamine sensitization in vivo. A4, a similar-affinity anti-S1 antibody, was less active in the toxin neutralization assays but more protective in the mouse infection model. A12, a low-affinity anti-S1 antibody, was least active in the assays of toxin neutralization but as effective as B9 in the infection model. These data suggest that epitopes on the A protomer and B oligomer may induce protective immunity. Measurement of pertussis toxin neutralization by monoclonal antibodies in in vitro and in vivo assays may not accurately predict protection against infection with B. pertussis.
Animals↗
Use of a Chinese hamster ovary cell cytotoxicity assay for the rapid diagnosis of pertussis.
A cytotoxicity assay with Chinese hamster ovary cells (CHO) capable of detecting 750 pg of pertussis toxin was assessed for use as a rapid test for the diagnosis of pertussis and compared with direct immunofluorescence (DFA). With pure bacterial cultures and simulated clinical specimens, the CHO assay detected as few as two colonies of Bordetella pertussis; no cytotoxicity occurred with other respiratory tract microorganisms. Next, nasopharyngeal aspirate secretions and nasopharyngeal cultures harvested after 72 h of incubation from 57 culture-positive and 201 culture-negative patients were examined. The CHO assay with nasopharyngeal secretions was positive in 25 (45%) of 55 culture-positive cases; DFA was positive in 15 (26%) of 57 cases (P = 0.05). The CHO assay with 72-h culture washes was positive in 42 (75%) of 57 culture-positive cases (P less than 0.001 compared with DFA). The CHO assay was more specific than DFA; all five CHO-positive, culture-negative cases were confirmed as true positives by serologic or toxin neutralization assays. In contrast, only 4 (36%) of 11 DFA-positive, culture-negative cases were confirmed as pertussis by serologic methods (P = 0.03). Combining the CHO assay with culture significantly decreased the delay in laboratory diagnosis of pertussis (3.30 versus 4.54 days; P = 0.01). The CHO assay is a sensitive and specific assay for the rapid diagnosis of pertussis.
Animals↗
Nutrient costing.
For the purpose of computing changes in food cost over time as well as the planning of proper nutrition education and dietary counselling, the cost of important Ethiopian foods was collected in Addis Ababa markets for three and one-half years and computed for the amount of energy and protein yield per unit price. In general, cereals and legumes faired well in their contribution of these nutrients at low cost. Certain foods, such as vetch, sugar and marmalades were also found to contribute a significant amount of nutrients at low cost. Because of the neurotoxic content in vetch and the contribution of a single nutrient as an energy source in the case of the latter two, their utilization during meal planning is subject to careful consideration. Foods of animal origin are second to last in their nutrient contribution per cost although their nutrient density makes them important in consumer demand. Root crops and vegetables that are known for their bulk are at the bottom of the list of good nutrient contributors per cost.
Dietary Services↗
Experimental respiratory infection with Bordetella pertussis in mice: comparison of two methods.
The mouse respiratory model is being used increasingly to study the pathogenesis and immunology of Bordetella pertussis infection. Two methods of inoculation, aerosol and intranasal, are routinely used to establish the infection. We compared the two methods of inoculation for reproducibility of infection using quantitative lung cultures and distribution of infection with [35S] methionine labeled bacteria and pulmonary histopathology. Ability to produce a respiratory infection intranasally was related to the inoculum volume; a minimum of 20 microliters was required although considerable variability remained. Lung bacterial counts in identically inoculated mice varied 1,000 fold following intranasal inoculation compared to only 5 fold following aerosol inoculation. Distribution of pulmonary 35S-labeled bacteria varied widely (right lung, 43-84%; left lung 16-57%) following intranasal in comparison to aerosol inoculation (right, 60-68%; left 32-40%). Finally, intranasal inoculation produced a scant, patchy, bronchopneumonia whereas diffuse pathology involving all pulmonary segments was seen following aerosol infection. Due to the superior reproducibility and predictable distribution of infection and pathology, aerosol inoculation is the method of choice for establishing the mouse model of pertussis respiratory infection.
Administration, Intranasal↗