Application of tissue culture methods to epidemiological studies of poliomyelitis

Evidence for frequent recombination within species human enterovirus B based on complete genomic sequences of all thirty-seven serotypes

The species Human enterovirus B (HEV-B) in the family Picornaviridae consists of coxsackievirus A9; coxsackieviruses B1 to B6; echoviruses 1 to 7, 9, 11 to 21, 24 to 27, and 29 to 33; and enteroviruses 69 and 73. We have determined complete genome sequences for the remaining 22 HEV-B serotypes whose sequences were not represented in public databases and analyzed these in conjunction with previously available complete sequences in GenBank. Members of HEV-B were monophyletic relative to all other human enterovirus species in all regions of the genome except in the 5'-nontranslated region (NTR), where they are known to cluster with members of HEV-A. Within HEV-B, phylogenies constructed from the structural (P1) and nonstructural regions of the genome (P2 and P3) are incongruent, suggesting that recombination had occurred. Similarity plots and bootscanning analysis across the complete genome identified multiple sites at which the phylogeny of a given strain's sequence shifted, indicating potential recombination points. These points are distributed in the 5'-NTR and throughout P2 and P3, but no sites with >80% bootstrap support were identified within the capsid. Individual sequence comparisons and phylogenetic analyses suggest that members of HEV-B have recombined with one another on multiple occasions, resulting in a complex mosaic of sequences derived from multiple parental viruses in the nonstructural regions of the genome. We conclude that RNA recombination is a common mechanism for enterovirus evolution and that recombination within the nonstructural regions of the genome (P2 and P3) has been observed only among members of the same species.

Virus aggregation as the cause of the non-neutralizable persistent fraction

The non-neutralizable or persistent fraction of virus populations has been found to be caused by aggregated virus. Detailed investigation was performed with the prototype strain of echovirus type 4 (Pesascek), as this virus is notorious for its large non-neutralizable fraction. When Pesascek virus was clarified by low-speed centrifugation, homologous antiserum hardly neutralized the virus. However, when the virus was filtered through membranes having a porosity only twice the diameter of the virus, monodispersed virus was obtained which was efficiently neutralized. Serum titers were up to 1,000 times higher if the neutralization test was carried out with monodispersed virus. Virus in non-neutralizable aggregates was found to constitute 30% of the infective units of unfiltered Pesascek virus but only 0.1% of the antigenically related DuToit strain. This explains why DuToit strain has been a more satisfactory indicator strain for detecting type 4 antibodies, regardless of the echo 4 strain used for inducing the antibodies. Clarified suspensions and ultrafiltrates of viruses belonging to the picorna-, reo-, myxo-, adeno-, herpes-, and poxvirus groups were studied. Clarified suspensions yielded persistent fractions of 0.005% for poliovirus, of 0.1% for reovirus, of 0.6% for influenza virus, of <0.001% for adenovirus, of 0.06% for herpesvirus, and of 10 to 30% for vaccinia virus. In all cases the persistent fractions were removed by membrane filters which had a pore diameter no larger than twice that of the virus under test, and the high concentration of virus in each ultrafiltrate was completely neutralized by antiserum.

Are-assessment of the risk of provoking paralytic poliomyelitis by making prophylactic inoculations against diphtheria and pertussis

The variables operating in respect of the risk of provoking paralytic poliomyelitis by inoculating children with different prophylactic reagents have been analysed.

It is concluded that the use of combined diphtheria fluid toxoid and pertussis vaccine, administered in early infancy, incurs a minimal risk and is to be recommended because of its immunological effciency, its unquestionable value in helping to maintain a high immunization rate against diphtheria in the child community and for its marked administrative convenience.

Aseptic meningitis caused by ECHO virus

1. An investigation of ninety-eight cases of aseptic meningitis admitted to hospital resulted in the isolation of ECHO virus Type 6 from fifty-one patients.

2. The viruses were cultivated in both human embryonic skin-muscle tissue and human amniotic cell tissue. The latter was found to be more satisfactory.

3. Forty-eight strains were isolated from the stools of patients, six from the cerebrospinal fluid and four from throat-washings.

4. Serological examination of patients from whom the virus was isolated showed that a significant proportion of patients exhibited a specific antibody response. This included three out of six patients with the virus in their cerebrospinal fluid.

5. The clinical picture of aseptic meningitis from which cases ECHO virus was isolated cannot be distinguished from that caused by other known viruses.

6. The evidence presented supports the claim that ECHO virus Type 6 is one of the causes of aseptic meningitis.

Grateful appreciation is acknowledged to Prof. P. M. Holst (Oslo), Prof. Johs. Böe (Bergen), Dr B. Helland-Hanssen (Molde), Dr O. Römcke (Drammen), Dr R. Tingstad (Namsos), and Dr A. H. Brinchmann (Bærum), for providing specimens and case records. I am also grateful to Mrs B. Zapffe and Mrs L. Kohmann for expert technical assistance.

Aseptic meningitis due to infection with ECHO virus (type 9)

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An endemiological study of enteric virus infections: poliomyelitis, coxsackie, and orphan (ECHO) viruses isolated from normal children in two socioeconomic groups

An endemiological study of enteric viruses was conducted among 136 normal children, living in households in two socio-economic groups, over a 29 month period in Charleston, West Virginia. A repeatable seasonal incidence of enteric virus excretion was noted with over 90 per cent of isolations occurring in the months of June to October. Of 592 stools examined in District I, a lower socio-economic group, 8.3 per cent yielded virus as compared to 3.1 per cent of 966 stools examined in District IV, an upper middle class district with good environmental sanitation. Among the 77 viruses isolated in tissue cultures of monkey kidneys, 44 per cent were ECHO or orphan viruses, 37 per cent Coxsackie viruses, and 19 per cent poliomyelitis viruses. Among poliovirus carriers, and 15 family contacts, 10 individuals had simultaneous heterotypic and type-specific antibody responses. The heterotypic ones were usually present at low levels and were transient in nature. Family infection with certain orphan viruses was also evident from antibody development which occurred following isolation of virus in the sentinel child.