Relationships of Coliform Organisms

Good Manufacturing Practices production and analysis of a DNA vaccine against dental caries

AIM

To prepare a clinical-grade anti-caries DNA vaccine pGJA-P/VAX and explore its immune effect and protective efficacy against a cariogenic bacterial challenge.

METHODS

A large-scale industrial production process was developed under Good Manufacturing Practices (GMP) by combining and optimizing common unit operations such as alkaline lysis, precipitation, endotoxin removal and column chromatography. Quality controls of the purified bulk and final lyophilized vaccine were conducted according to authoritative guidelines. Mice and gnotobiotic rats were intranasally immunized with clinical-grade pGJA-P/VAX with chitosan. Antibody levels of serum IgG and salivary SIgA were assessed by an enzyme-linked immunosorbent assay (ELISA), and caries activity was evaluated by the Keyes method. pGJA-P/VAX and pVAX1 prepared by a laboratory-scale commercial kit were used as controls.

RESULTS

The production process proved to be scalable and reproducible. Impurities including host protein, residual RNA, genomic DNA and endotoxin in the purified plasmid were all under the limits of set specifications. Intranasal vaccination with clinical-grade pGJA-P/VAX induced higher serum IgG and salivary SIgA in both mice and gnotobiotic rats. While in the experimental caries model, the enamel (E), dentinal slight (Ds), and dentinal moderate (Dm) caries lesions were reduced by 21.1%, 33.0%, and 40.9%, respectively.

CONCLUSION

The production process under GMP was efficient in preparing clinical-grade pGJA-P/VAX with high purity and intended effectiveness, thus facilitating future clinical trials for the anti-caries DNA vaccine.

Erwinia -Like Microorganisms Isolated from Animal and Human Hosts

Erwinia -like microorganisms were isolated from the vital organs of more than 40% of a large deer population examined as well as from 13% of a small random sampling. Over a brief period of observation, a similar isolate was recovered from throat cultures of two children and one adolescent. There is no obvious explanation of the presence of the plant pathogen or its significance under these circumstances.

Bacteriology of fresh water: II. The distribution and types of coliform bacteria in lakes and streams

1. The distribution of coliform bacteria in lakes and streams has been studied. Weekly samples have been collected from different depths from the north and south basins of Windermere, from Thirlmere, and Bsthwaite Water, dnd from streams flowing into these lakes. Nearly 300 cultures have been isolated from positive tubes of MacConkey broth and their relationship to the coliform group has been studied and considered.

2. In relatively unpolluted streams the counts of coliform bacteria and the plate counts on sodium casemate agar tended to fluctuate in the same direction as river level, but in polluted streams the increased flow of water accompanying a higher river level reduced the numbers of bacteria per unit volume. Counts of coliform bacteria were, in general, much higher in summer than in winter, despite the lower rainfall in summer.

3. During the winter period of circulation of the water, samples of water from different depths in the lakes gave approximately the same count for coliform bacteria. When stratification of the water became established numbers of coliform bacteria in the hypolimnion (the lower stratum) dropped to very low figures and remained fairly constant; much higher counts were found in the epilimnion (the upper stratum).

Large fluctuations in numbers of coliform bacteria which occurred from week to week in the lakes were related to fluctuations in plate counts at only one of the seven sampling points, and were not related to previous rainfall. The count of coliform bacteria was greatest in summer and autumn, a phenomenon that was by no means entirely a result of the bacteria which were washed in being concentrated in the epilimnion. It is suggested that temperature may have affected viability and proliferation.

4. Of the total number of coliform organisms producing acid and gas from lactose at 37° C, approximately 70% wereBact. colitypes I and II, and the remainder were members of the I.A.C. group. In the relatively pure waters of Thirlmere and its inflowsBact. coli, type I, made up 86 and 98% respectively of the total coliform cultures isolated, whereas in the relatively impure waters of Windermere and Esthwaite Water the percentages were 39 and 37 respectively. The differences were due to the greater proportions ofBact. aerogenes, type I, and of intermediate and irregular types in the impure waters. The significance of greater proportions of the I.A.C. group in polluted rather than in unpolluted water is discussed. The actual counts of coliform bacteria were very much lower in Thirlmere than in the other lakes examined.

5. Of the total cultures isolated from positive tubes of MacConkey broth 27% did not produce acid and gas in MacConkey broth at 37° C. Approximately one-half of these cultures, however, fermented lactose at 30° C, and gave varied results with the standard differential tests. The majority of these cultures could, by gradually increasing the incubation temperatures of successive inoculations, be “trained” to ferment lactose at 37° C but not at 40° C. They were more frequently isolated from the polluted lakes and inflows than from unpolluted waters. The remaining organisms isolated proved to be non-lactose-fermenting species belonging to the generaProteus, Salmonella, EberthellaandAlkaligenes(Bergey).