Structural requirements for initiation of cross-reactivity and CNS autoimmunity with a PLP139-151 mimic peptide derived from murine hepatitis virus

MS is an autoimmune CNS demyelinating disease in which infection appears to be an important pathogenic factor. Molecular mimicry, the cross‐activation of autoreactive T cells by mimic peptides from infectious agents, is a possible explanation for infection‐induced autoimmunity. Infection of mice with a non‐pathogenic strain of Theiler's murine encephalomyelitis virus (TMEV) engineered to express an epitope from Haemophilus influenzae (HI) sharing 6/13 amino acids with the dominant proteolipid protein (PLP) epitope, PLP_139–151, can induce CNS autoimmune disease. Here we demonstrate that another PLP_139–151 mimic sequence derived from murine hepatitis virus (MHV) which shares only 3/13 amino acids with PLP_139–151 can also induce CNS autoimmune disease, but only when delivered by genetically engineered TMEV, not by immunization with the MHV peptide. Further, we demonstrate the importance of proline at the secondary MHC class II contact residue for effective cross‐reactivity, as addition of this amino acid to the native MHV sequence increases its ability to cross‐activate PLP_139–151‐specific autoreactive T cells, while substitution of proline in the HI mimic peptide has the opposite effect. This study describes a structural requirement for potential PLP_139–151 mimic peptides, and provides further evidence for infection‐induced molecular mimicry in the pathogenesis of autoimmune disease.

Epidemiology of fetal alcohol syndrome in a South African community in the Western Cape Province

OBJECTIVES

This study determined the characteristics of fetal alcohol syndrome in a South African community, and methodology was designed for the multidisciplinary study of fetal alcohol syndrome in developing societies.

METHODS

An active case ascertainment, 2-tier methodology was used among 992 first-grade pupils. A case-control design, using measures of growth, development, dysmorphology, and maternal risk, delineated characteristics of children with fetal alcohol syndrome.

RESULTS

A high rate of fetal alcohol syndrome was found in the schools--40.5 to 46.4 per 1000 children aged 5 to 9 years--and age-specific community rates (ages 6-7) were 39.2 to 42.9. These rates are 18 to 141 times greater than in the United States. Rural residents had significantly more fetal alcohol syndrome. After control for ethnic variation, children with fetal alcohol syndrome had traits similar to those elsewhere: poor growth and development, congruent dysmorphology, and lower intellectual functioning.

CONCLUSIONS

This study documented the highest fetal alcohol syndrome rate to date in an overall community population. Fetal alcohol syndrome initiatives that incorporate innovative sampling and active case ascertainment methods can be used to obtain timely and accurate data among developing populations.

Alcohol consumption by pregnant women in the Western Cape

OBJECTIVE

To assess alcohol use by pregnant women in three underprivileged areas of the Western Cape.

DESIGN

Data were collected from subjects, selected in a randomised manner, during a single, structured interview.

SUBJECTS AND SETTING

Interviews were conducted among pregnant women voluntarily attending selected antenatal clinics in the George/Oudtshoorn, Vredenburg/Saldanha, and Cape Metropole areas of the Western Cape.

OUTCOME MEASURES

On completion of the interview, women at risk were counselled with regard to the dangers of prenatal alcohol exposure to the fetus.

RESULTS

42.8% of the women in the sample admitted to varying degrees of alcohol ingestion during the current pregnancy. The reported alcohol intake of over 55% of these women, i.e. 23.7% of the sample, was sufficient to place their unborn children at high risk for the fetal alcohol syndrome (FAS). These heavy drinkers followed a pattern of binge drinking over weekends and showed a marked preference for beer. Combined alcohol and tobacco use occurred in 29.6% of the sample. Only one subject admitted to using marijuana.

CONCLUSION

The data in this study confirm that a high rate of alcohol and tobacco use prevails among pregnant women in poorer communities of the Western Cape. Extrapolating from experience, as many as 9.5% of the sample may produce children with FAS.

Cloning and expression of murine IFN beta and a TNF antagonist for gene therapy of experimental allergic encephalomyelitis

Immunomodulation of an ongoing autoimmune disease can be achieved by inhibitory cytokines or cytokine inhibitors such as TNF antagonists, delivery by gene therapy. The aim of this study was to design and test plasmid and retrovirus vectors expressing the mouse IFN beta gene and a chimeric protein containing the extracellular domain of human p55 TNF receptor linked to a murine Ig. These vectors were transiently expressed in COS-7 cells and permanently in amphotropic packaging cell lines or ABH mouse immortalized fibroblasts. Expression levels were assessed by ELISA. Western blotting and biological activity. In order to achieve tissue-specific expression in the CNS, the IFN beta gene was cloned and expressed under the control of the rat NSE promoter. We evaluated these constructs by direct intracranial injections of DNA-liposome complexes during the induction phase of experimental allergic encephalomyelitis, a murine model of multiple sclerosis, with therapeutic benefit.