Prospective study of bacterial meningitis in North East Thames region, 1991-3, during introduction of Haemophilus influenzae vaccine.

OBJECTIVE--To describe the epidemiology of primary bacterial meningitis in the North East Thames region over a three year period before and during the introduction of the vaccine for Haemophilus influenzae type b. DESIGN--Analysis of information on cases of primary bacterial meningitis identified by microbiology laboratories in the region, with collection of case data by questionnaire. MAIN OUTCOME MEASURES--Annual incidence rates for types of meningitis according to age and ethnic group. RESULTS--The annual incidence rates for the three major causes of bacterial meningitis in the general population were 1.9/100,000 for Neisseria meningitidis, 1.6/100,000 for Haemophilus influenzae before vaccination, and 1.0/100,000 for Streptococcus pneumoniae. Higher rates of H influenzae meningitis were found in Asians compared with white people (3.6/100,000 v 1.5/100,000, P = 0.01). As a result of the vaccine programme introduced in October 1992 the number of cases of H influenzae meningitis in children under 5 years has fallen by 87%. CONCLUSIONS--Bacterial meningitis is a serious problem especially in preschool children. There are differences in the incidence of some causes of bacterial meningitis in different ethnic groups; with H influenzae type b being significantly more common among black and Asian people than among white people. The immunisation programme for H influenzae type b in the North East Thames region has been successful in reducing the incidence of this type of meningitis in Asian and white populations. The numbers were too small to evaluate in the black population.     

Big flies, small repeats: the "Thr-Gly" region of the period gene in Diptera

The region of the clock gene period (per) that encodes a repetitive tract of threonine-glycine (Thr-Gly) pairs has been compared between Dipteran species both within and outside the Drosophilidae. All the non- Drosophilidae sequences in this region are short and present a remarkably stable picture compared to the Drosophilidae, in which the region is much larger and extremely variable, both in size and composition. The accelerated evolution in the repetitive region of the Drosophilidae appears to be mainly due to an expansion of two ancestral repeats, one encoding a Thr-Gly dipeptide and the other a pentapeptide rich in serine, glycine, and asparagine or threonine. In some drosophilids the expansion involves a duplication of the pentapeptide sequence, but in Drosophila pseudoobscura both the dipeptide and the pentapeptide repeats are present in larger numbers. In the nondrosophilids, however, the pentapeptide sequence is represented by one copy and the dipeptide by two copies. These observations fulfill some of the predictions of recent theoretical models that have simulated the evolution of repetitive sequences.      

Transgenic Arabidopsis leaf tissue expressing a modified oryzacystatin shows resistance to the field slug Deroceras reticulatum (Müller)

Transgenic Arabidopsis thaliana has been developed which expresses the oryzacystatin mutant OCI86, which is an inhibitor of the major proteinase present in the digestive gland of the slug, Deroceras reticulatum. When fed on leaf tissue from plants expressing this inhibitor the growth of juvenile slugs was significantly reduced by 31% compared with those feeding on control leaf tissue. Furthermore, while surviving slugs did not individually consume less when feeding on leaf tissue expressing OCI86, the total amount of leaf tissue eaten was 50% less, due to reduced survival of slugs. The synthetic cysteine proteinase inhibitors E64 and leupeptin also significantly reduced slug weight gain (by at least 40%) and digestive gland cysteine proteinase activity when administered in an artificial diet, indicating that their antimetabolic effects are due to direct inhibition of gut proteolytic activity. These results suggest that transgenic crop plants expressing phytocystatins could be used to suppress the growth rates of slug populations in the field.     

Preferential expression of a plant cystatin at nematode feeding sites confers resistance to Meloidogyne incognita and Globodera pallida

The expression patterns of three promoters preferentially active in the roots of Arabidopsis thaliana have been investigated in transgenic potato plants in response to plant parasitic nematode infection. Promoter regions from the three genes, TUB-1, ARSK1 and RPL16A were linked to the GUS reporter gene and histochemical staining was used to localize expression in potato roots in response to infection with both the potato cyst nematode, Globodera pallida and the root-knot nematode, Meloidogyne incognita. All three promoters directed GUS expression chiefly in root tissue and were strongly up-regulated in the galls induced by feeding M. incognita. Less activity was associated with the syncytial feeding cells of the cyst nematode, although the ARSK1 promoter was highly active in the syncytia of G. pallida infecting soil grown plants. Transgenic potato lines that expressed the cystatin OcIDeltaD86 under the control of the three promoters were evaluated for resistance against Globodera sp. in a field trial and against M. incognita in containment. Resistance to Globodera of 70 +/- 4% was achieved with the best line using the ARSK1 promoter with no associated yield penalty. The highest level of partial resistance achieved against M. incognita was 67 +/- 9% using the TUB-1 promoter. In both cases this was comparable to the level of resistance achieved using the constitutive cauliflower mosaic virus 35S (CaMV35S) promoter. The results establish the potential for limiting transgene expression in crop plants whilst maintaining efficacy of the nematode defence.