[Enterovirus infections in children under three months of age]. / Les infections à entérovirus du nourrisson de moins de trois mois.

Enterovirus infections in childhood (echoviruses, coxsackie viruses A and B, unclassified enteroviruses) are varied, nonspecific and benign (except for poliovirus infections). However, in infants, they may lead to severe neurological or cardiac lesions. In neonates, enterovirus infections are difficult to distinguish from late-onset bacterial infection. Maternal-fetal or postnatal transmission can induce early spontaneous abortions or severe neonatal infections. Diagnosis is usually based on viral cultures and, in recent years, on PCR techniques. At the present time, no potential effective drug is available: intravenous immunoglobulins, immunization or anti-proteases may be of interest.

Nucleotide sequence of an attenuated mutant of coxsackievirus B3 compared with the cardiovirulent wildtype: assessment of candidate mutations by analysis of a revertant to cardiovirulence.

BACKGROUND: Coxsackievirus B3 (CVB3) causes myocarditis in the SWR (H2q) mouse model and persistence of CVB3 in myocardium disposes to the development of dilated cardiomyopathy. An attenuated strain of CVB3 has been isolated, sequenced and several candidate mutations for attenuation identified. Derivation of a revertant to cardiovirulence allows the significance of these mutations to be assessed. OBJECTIVES: To ascertain which candidate mutation(s) determine(s) the attenuated phenotype. STUDY DESIGN: A revertant to cardiovirulence was isolated following passage through severe combined immunodeficient disease (SCID) mouse heart. The 5'-non-translated region (NTR) and region coding for capsid proteins were sequenced and compared to the wildtype and attenuant. RESULTS: There are five candidates for attenuation: (1) A-G at base 580 in the 5'-NTR; (2) A-T at base 690 in the 5'-NTR; (3) CG-GC at bases 1401/2 (Thr to Ser at amino acid 151 in VP2); (4) AA-GT at bases 2691/2 (Lys to Ser at amino acid 80 in VP1); (5) A-G at base 2916 (Asp to Gly at amino acid 155 in VP1). It was shown previously that mutations at 580, 690 and 2691/2 are not important in attenuation. Additionally, there are three novel mutations in the coding region of the revertant and one in the 5'-NTR which are unlikely to be relevant for attenuation as they are not present in the attenuant. Of nucleotide changes seen at 1401/2 and 2916 in the attenuant, only 2916 reverts to the wildtype sequence and so is a strong candidate for a determinant of attenuation.