Adult polio-like syndrome following Enterovirus 70 conjunctivitis (natural history of the disease)

Is it time to switch to a formulation other than the live attenuated poliovirus vaccine to prevent poliomyelitis?

The polioviruses (PVs) are mainly transmitted by direct contact with an infected person through the fecal-oral route and respiratory secretions (or more rarely via contaminated water or food) and have a primary tropism for the gut. After their replication in the gut, in rare cases (far less than 1% of the infected individuals), PVs can spread to the central nervous system leading to flaccid paralysis, which can result in respiratory paralysis and death. By the middle of the 20th century, every year the wild polioviruses (WPVs) are supposed to have killed or paralyzed over half a million people. The introduction of the oral poliovirus vaccines (OPVs) through mass vaccination campaigns (combined with better application of hygiene measures), was a success story which enabled the World Health Organization (WHO) to set the global eradication of poliomyelitis as an objective. However this strategy of viral eradication has its limits as the majority of poliomyelitis cases today arise in individuals infected with circulating vaccine-derived polioviruses (cVDPVs) which regain pathogenicity following reversion or recombination. In recent years (between January 2018 and May 2023), the WHO recorded 8.8 times more cases of polio which were linked to the attenuated OPV vaccines (3,442 polio cases after reversion or recombination events) than cases linked to a WPV (390 cases). Recent knowledge of the evolution of RNA viruses and the exchange of genetic material among biological entities of the intestinal microbiota, call for a reassessment of the polio eradication vaccine strategies.

Structure of Human Enterovirus 70 and Its Inhibition by Capsid-Binding Compounds

Enterovirus 70 (EV70) is a human pathogen belonging to the family Picornaviridae. EV70 is transmitted by eye secretions and causes acute hemorrhagic conjunctivitis, a serious eye disease. Despite the severity of the disease caused by EV70, its structure is unknown. Here, we present the structures of the EV70 virion, altered particle, and empty capsid determined by cryo-electron microscopy. The capsid of EV70 is composed of the subunits VP1, VP2, VP3, and VP4. The partially collapsed hydrophobic pocket located in VP1 of the EV70 virion is not occupied by a pocket factor, which is commonly present in other enteroviruses. Nevertheless, we show that the pocket can be targeted by the antiviral compounds WIN51711 and pleconaril, which block virus infection. The inhibitors prevent genome release by stabilizing EV70 particles. Knowledge of the structures of complexes of EV70 with inhibitors will enable the development of capsid-binding therapeutics against this virus.

IMPORTANCE Globally distributed enterovirus 70 (EV70) causes local outbreaks of acute hemorrhagic conjunctivitis. The discharge from infected eyes enables the high-efficiency transmission of EV70 in overcrowded areas with low hygienic standards. Currently, only symptomatic treatments are available. We determined the structures of EV70 in its native form, the genome release intermediate, and the empty capsid resulting from genome release. Furthermore, we elucidated the structures of EV70 in complex with two inhibitors that block virus infection, and we describe the mechanism of their binding to the virus capsid. These results enable the development of therapeutics against EV70.

Acute Flaccid Paralysis and Enteroviral Infections

PURPOSE OF REVIEW

The focus of this review is on enterovirus (EV)-associated acute flaccid paralysis (AFP) due to spinal cord anterior horn cell disease. Emphasis is placed on the epidemiology, pathogenesis, diagnosis, treatment, and outcome of AFP caused by polioviruses, vaccine-derived polioviruses, EV-D68, and EV-A71.

RECENT FINDINGS

Since the launch of The Global Polio Eradication Initiative in 1988, the worldwide incidence of polio has been reduced by 99.9%, with small numbers of poliomyelitis cases being reported only in Afghanistan, Pakistan, and Nigeria. With the planned phaseout of oral polio vaccine, vaccine-associated poliomyelitis is also expected to be eliminated. In their place, other EVs, chiefly EV-D68 and EV-A71, have emerged as the principal causes of AFP. There is evidence that the emergence of EV-D68 as a cause of severe respiratory disease and AFP was due to recent genetic virus evolution. Antiviral medications targeting EV-D68, EV-A71, and other EVs will likely be available in the near future. An effective EV-A71 vaccine has been developed, and preliminary investigations suggest an EV-D68 vaccine could be on the horizon. The eradication of poliomyelitis and vaccine-associated poliomyelitis is near, after which other EVs, presently EV-D68 and EV-A71, will be the principle viral causes of AFP. Moving forward, it is essential that EV outbreaks, in particular those associated with neurologic complications, be investigated carefully and the causal strains identified, so that treatment and prevention efforts can be rapidly developed and implemented.

Towards an in vitro model for acute hemorrhagic conjunctivitis: cytokine-mediated vascular endothelial cell activation triggered by enterovirus type 70 infection

BACKGROUND

Little is known of the pathogenetic mechanisms of enterovirus type 70 (EV70), a causative agent of acute hemorrhagic conjunctivitis. However, virus- or cytokine-induced perturbation of vascular endothelial cells are potential triggering events.

OBJECTIVE

To determine whether EV70 infection of human umbilical vascular endothelial cells (HUVECs) and human corneal epithelial cells (HCEs) causes the release of vasoactive cytokines, capable of triggering vascular endothelial cell activation.

STUDY DESIGN

Susceptibility of cultured HUVECs and HCEs to EV70 was tested by observing the appearance of cytopathic effect or immunoprecipitation of viral protein in infected cells. The culture fluids from the virus-infected cells were tested for their ability to stimulate the expression of intercellular adhesion molecule-1 (ICAM-1) on uninfected HUVECs. Anti-cytokine antibodies were used to identify ICAM-1-activating cytokine(s).

RESULTS

Both HUVECs and HCEs were susceptible to EV70 infection. Culture fluids from EV70-infected HUVECs and HCEs stimulated ICAM-l expression on uninfected HUVECs, which was completely blocked by anti-interleukin-1alpha (IL-1alpha) antibody but not by interleukin-1beta (IL-1beta) or anti-tumor necrosis factor alpha (TNFalpha) antibodies.

CONCLUSION

This study provides the first evidence of EV70 infection of both HCEs and HUVECs, and furthermore, identifies IL-1alpha as the predominant endothelial cell-activating factor produced by EV70-infected cells. Since endothelial cell activation is often an initiating step towards vascular permeability and/or inflammation, the perturbation of endothelial cell function through EV70 induced IL-1alpha is thus a potential contributory factor in the pathogenesis of EV70-associated hemorrhagic conjunctivitis.

Poliomyelitis

1996 is polio awareness year. This paper reviews the clinical syndrome of acute paralytic poliomyelitis and its sequelae. We discuss epidemiological studies of the syndrome of late functional deterioration many years after the acute infection and the current hypotheses of the pathophysiology of such disorders. Recent evidence has suggested that potentially treatable factors may be implicated in the majority of such patients and it is therefore important to exclude such disorders before attributing late functional deterioration to progressive post-polio muscular atrophy.

Isolation of enterovirus 70 (EV70) from patients with acute haemorrhagic conjunctivitis in two areas of Saudi Arabia

This is the first epidemic of acute haemorrhagic conjunctivitis (AHC) reported from Saudi Arabia in which enterovirus 70 (EV70) was implicated as aetiological agent. EV70 was isolated from 5 of 29 conjunctival scrapings from patients with AHC. Two human diploid cell lines, human skin fibroblast (HSF) and human embryonic lung fibroblast (MRC-5), were quite sensitive for the isolation of this virus. The relatively high isolation rate could also be attributed to the timing of collection of specimens and perhaps to the fact that conjunctival scrapings contained more virus particles than did eye swabs.

[Acute hemorrhagic conjunctivitis, in Cuiabá, Mato Grosso, Brazil 1983]

Foi feita investigação de natureza etiológica clínica e laboratorial durante uma epidemia de conjuntivite hemorrágica aguda (CHA), ocorrida em Cuiabá, MT durante os meses de dezembro de 1982 e fevereiro de 1983; atendidos 68 pacientes e colhidos espécimes da conjuntiva, orofaringe e soro. Em 28 pares de soros foram realizados testes de neutralização em tubos de cultura de tecidos para o enterovirus 70 (EV 70) e fixaço do complemento para os adenovirus. Os resultados revelaram conversão sorológica de 89,3% (25 pares de soro) para o EV 70. A Secretaria de Saúde do Estado do Mato Grosso estima que aproximadamente 70% da população tenha sido atingida durante o surto. Não foram observadas evidências de comprometimento neurológico em pacientes de conjuntivite, durante ou logo após o surto.

Neurological complications of acute haemorrhagic conjunctivitis

Forty four cases of the neurological complications of acute haemorrhagic conjunctivitis (AHC) seen in India during 1981 epidemic are reported. The disease predominantly affected adult males. The preceding attack of AHC, a latent period, prodromal symptoms of fever, myalgia and root pains followed by acute onset of lower motor neurone paralysis of limbs and/or cranial nerves formed the classical picture of neurological involvement. The recovery was poor and nearly half of the patients remained severely handicapped. Electrophysiological studies showed early appearance of widespread fibrillations and fasciculations, large polyphasic potentials of increased amplitude and reduced interference pattern. Nerve conduction studies were normal in most of the cases. Cerebrospinal fluid (CSF) examination revealed lymphocytic pleocytosis and rise in protein content. Significant antibody titres against enterovirus type 70 (EV 70) were demonstrated in the serum and the CSF. HLA studies showed low occurrence of A2 and B15 HLA antigens. Muscle biopsies revealed neurogenic atrophy and sural nerve biopsies were histologically unremarkable. The similarities of this disease with poliomyelitis and its pathogenesis are discussed.

Polyradiculoneuritis in children groups during simultaneous circulation of enteroviruses and adenoviruses

Two cases of polyradiculoneuritis in children were noted during January, 1984. Each girl was a member of a different group of children: the first group was newly constituted of children from various remote regions of Czechoslovakia in a Medical Institution, the second one included children attending the same nursery school for a long time. In both groups, all or most of the children went through one or two respiratory infections which preceded the development of a paralytic disease. From the first girl, coxsackievirus A9 was recovered in nasopharyngeal swabs and in a stool sample. Among contacts in the Children's Medical Institution, a concurrent circulation of this enterovirus and of an adenovirus type 3 was demonstrated by isolation attempts and confirmed by serological examinations. From the second girl, coxsackie A9 and an adenovirus type 29 were demonstrated in the same stool sample and a simultaneous circulation of both virus species among the nursery school and family contacts was proved by isolation attempts and by serological investigations. The concurrent, overlapping or sequential circulation of adenoviruses and enteroviruses may perhaps contribute to a compromised immunity resulting in a manifestation of paralysis.