Isolation of an intertypic poliovirus capsid recombinant from a child with vaccine-associated paralytic poliomyelitis

The isolation of a capsid intertypic poliovirus recombinant from a child with vaccine-associated paralytic poliomyelitis is described. Virus 31043 had a Sabin-derived type 3-type 2-type 1 recombinant genome with a 5'-end crossover point within the capsid coding region. The result was a poliovirus chimera containing the entire coding sequence for antigenic site 3a derived from the Sabin type 2 strain. The recombinant virus showed altered antigenic properties but did not acquire type 2 antigenic characteristics. The significance of the presence in nature of such poliovirus chimeras and the consequences for the current efforts to detect potentially dangerous vaccine-derived poliovirus strains are discussed in the context of the global polio eradication initiative.

The efficiency and reliability of polio surveillance

Surveillance for acute flaccid paralysis (AFP) in children younger than 15 years, and careful investigation of the cases, are the cornerstones for monitoring the progress of the poliomyelitis eradication programme. However, its sensitivity to detect wild type poliovirus (wtPV) circulation decreases when the incidence of true polio cases approaches zero. Under these conditions, only about one in 100,000 children is being investigated for poliovirus excretion. No real alternative approach which is generally exploitable has been developed. Environmental surveillance may in optimal conditions be at least as sensitive in detecting poliovirus circulation as AFP surveillance. However, optimal conditions, i.e. converging sewage systems, are not used by most people in the remaining endemic countries. Enterovirus surveillance, based on isolation of poliovirus in the routine diagnostic services, is only applicable in a few countries, where the diagnostic activity covers the entire population. Whichever approach is used, we will never reach 100% certainty of complete elimination of wtPV circulation. However, by applying all these approaches optimally, we may eventually reach a probability level allowing the safe cessation of immunisation.

BCL-2 and BAX protect adult mice from lethal Sindbis virus infection but do not protect spinal cord motor neurons or prevent paralysis

Cellular proteins that regulate apoptotic cell death can modulate the outcome of Sindbis virus (SV) encephalitis in mice. Both endogenous and overexpressed BCL-2 and BAX proteins protect newborn mice from fatal SV infection by blocking apoptosis in infected neurons. To determine the effects of these cellular factors on the course of infection in older animals, a more neurovirulent SV vector (dsNSV) was constructed from a viral strain that causes both prominent spinal cord infection with hind-limb paralysis and death in weanling mice. This vector has allowed assessment of the effects of BCL-2 and BAX on both mortality and paralysis in these hosts. Similar to newborn hosts, weanling mice infected with dsNSV encoding BCL-2 or BAX survived better than animals infected with control viruses. This finding indicates that BCL-2 and BAX both protect neurons that mediate host survival. Neither cellular factor, however, could suppress the development of hind-limb paralysis or prevent the degeneration of motor neurons in the lumbar spinal cord. Infection of BAX knockout mice with dsNSV demonstrated that endogenous BAX also enhances the survival of animals but has no effect on paralysis. These findings for the spinal cord are consistent with earlier data showing that dying lumbar motor neurons do not exhibit an apoptotic morphology. Thus, divergent cell death pathways are activated in different target populations of neurons during neurovirulent SV infection of weanling mice.

The peroxisome proliferator phenylbutyric acid (PBA) protects astrocytes from ts1 MoMuLV-induced oxidative cell death

Oxidative stress is involved in the pathogenesis of several neurodegenerative diseases, including Parkinson's disease, Alzheimer's disease, and HIV neuroAIDS. In this study, we have investigated an agent, phenylbutyric acid, that ameliorates cell death in murine astrocytes infected with ts1 MoMuLV (ts1). Phenylbutyric acid, an aromatic short chain fatty acid, was shown to prevent the loss of catalase that occurs in ts1 infected astrocytes, and to prevent ts1-mediated cell death. Cell cotransfection studies demonstrated that phenylbutyric acid activates peroxisome proliferator receptors (PPARs) in astrocytes, and binds to the peroxisome proliferator-activated receptors alpha and gamma. This observation suggests that the effects of PBA may be mediated by PPARs in astrocytes. Phenylbutyric acid also maintained catalase protein levels in brain of ts1-infected mice, and delayed the hindlimb paralysis caused by ts1 infection. Because PBA activates peroxisome proliferator-activated receptors and prevents loss of catalase, we suggest that ts1-induced oxidative stress in infected astrocytes that is alleviated by PBA is mediated via PPARalpha and/or PPARgamma.

Neuroinvasion during delayed primary HHV-7 infection in an immunocompetent adult with encephalitis and flaccid paralysis

Antibody avidity tests have been used to detect primary human herpesvirus-7 (HHV-7) infection in an immunocompetent 19-year-old man with encephalitis and flaccid paralysis for which all other suspected causes had been excluded. The finding of the viral DNA in the cerebrospinal fluid (CSF) but not in serum samples suggests that primary HHV-7 infection with invasion of the central nervous system and consequential disease had occurred. As almost all adults are infected with HHV-7 in early childhood, the present case of delayed primary infection with serious symptoms must be exceptionally rare and no cases of such late acquisition of the virus have been documented in the literature. This report of HHV-7 DNA in the CSF of an immunocompetent adult is also unique.

Critical role for protein tyrosine phosphatase SHP-1 in controlling infection of central nervous system glia and demyelination by Theiler's murine encephalomyelitis virus

We previously characterized the expression and function of the protein tyrosine phosphatase SHP-1 in the glia of the central nervous system (CNS). In the present study, we describe the role of SHP-1 in virus infection of glia and virus-induced demyelination in the CNS. For in vivo studies, SHP-1-deficient mice and their normal littermates received an intracerebral inoculation of an attenuated strain of Theiler's murine encephalomyelitis virus (TMEV). At various times after infection, virus replication, TMEV antigen expression, and demyelination were monitored. It was found that the CNS of SHP-1-deficient mice uniquely displayed demyelination and contained substantially higher levels of virus than did that of normal littermate mice. Many infected astrocytes and oligodendrocytes were detected in both brains and spinal cords of SHP-1-deficient but not normal littermate mice, showing that the virus replicated and spread at a much higher rate in the glia of SHP-1-deficient animals. To ascertain whether the lack of SHP-1 in the glia was primarily responsible for these differences, glial samples from these mice were cultured in vitro and infected with TMEV. As in vivo, infected astrocytes and oligodendrocytes of SHP-1-deficient mice were much more numerous and produced more virus than did those of normal littermate mice. These findings indicate that SHP-1 is a critical factor in controlling virus replication in the CNS glia and virus-induced demyelination.

Poliovirus pathogenesis in a new poliovirus receptor transgenic mouse model: age-dependent paralysis and a mucosal route of infection

We constructed a poliovirus receptor (PVR) transgenic mouse line carrying a PVR delta cDNA driven by a beta-actin promoter. We refer to this model as the cPVR mouse. The cPVR mice express Pvr in a variety of tissues (including small intestines, brain, spinal cord, muscle, blood and liver) and are susceptible to infection after intraperitoneal, intracerebral or intramuscular inoculation of poliovirus. After intraperitoneal inoculation, poliovirus replication is observed in cPVR muscle, brain, spinal cord and, notably, small intestine. The cPVR mice exhibit a striking age-dependent paralysis after intramuscular infection, with 2-week-old mice being 10,000-fold more susceptible to paralytic disease than adult mice. The cPVR mice are also susceptible to paralysis following intranasal infection with poliovirus. After intranasal infection, virus replication is observed in the olfactory bulb, cerebrum, brain stem and spinal cord, suggesting that intranasal infection of cPVR mice is a model for bulbar paralysis. Intranasally infected mice frequently display unusual neurological behaviours. The PVR transgenic mouse reported here provides the first available model for a mucosal route of infection with poliovirus.

[Abdominal distension due to herpes zoster]

A case is reported in which an abdominal protrusion appeared in relation with a zosteric eruption at 11th dorsal dermatome. The motor deficit in zoster is unusual (2-3% in the reported series) and generally recognized when the extremities are affected. The frequency with which the abdominal muscles are involved is estimated to be around 0.17%, according to a clinical series. The aim of this report is to draw attention to the abdominal wall paresis that can result when zoster involves the caudal dorsal dermatomyotomes. This in turn, leads to abdominal distension which needs to be differentiated from other causes.

[Evaluation of an ELISA kit made in our laboratory for intratypic discrimination of poliovirus type 1 strains isolated from acute flask paralysis]

In this study, we aimed to develop and evaluate an enzyme based immunological method (ELISA) for the intratypic differentiation (whether if Sabin like-SL, or non Sabin like/wild type-NSL) of poliovirus type 1 isolates, in the frame of Polio Eradication Programme (PEP) in Turkey. Five poliovirus type 1 strains which were formerly isolated and identified in our laboratory from fecal samples of acute flask paralysis (AFP) patients, and standard reference strains of vaccine type 1 and prototype wild (Mahoney) polioviruses have been tested into plate wells that bounded with 5 different monoclonal antibodies (mAbs B18, S2-36, M18, B82, M49). The wells which gave high absorbance than cutoff value estimated by comparing negative control wells, were accepted as positive. As a result, the standard poliovirus strains were differentiated correctly, whereas 2 patient isolates were identified as SL and 3 were NSL. In conclusion, our home-made ELISA method found to be successful for intratypic differentiation of poliovirus type 1 isolates, however more detailed studies are necessary in order to increase the susceptibility and specificity of this test.

Using the two-source capture-recapture method to estimate the incidence of acute flaccid paralysis in Victoria, Australia

OBJECTIVE

To estimate the incidence and the completeness of ascertainment of acute flaccid paralysis (AFP) in Victoria, Australia, in 1998-2000 and to determine its common causes among children aged under 15 years.

METHODS

: The two-source capture-recapture method was used to estimate the incidence of cases of AFP and to evaluate case ascertainment in the routine surveillance system. The primary and secondary data sources were notifications from this system and inpatient hospital records, respectively.

FINDINGS

The routine surveillance system indicated that there were 14 cases and the hospital record review identified 19 additional cases. According to the two-source capture-recapture method, there would have been 40 cases during this period (95% confidence interval (CI) = 29-51), representing an average annual incidence of 1.4 per 100000 children aged under 15 years (95% CI = 1.1- 1.7). Thus case ascertainment based on routine surveillance was estimated to be 35% complete. Guillain-Barré syndrome was the commonest single cause of AFP.

CONCLUSIONS

Routine surveillance for AFP in Victoria was insensitive. A literature review indicated that the capture-recapture estimates obtained in this study were plausible. The present results help to define a target notification rate for surveillance in settings where poliomyelitis is not endemic.

Genetic control of neuroadapted sindbis virus replication in female mice maps to chromosome 2 and associates with paralysis and mortality

Neuroadapted Sindbis virus (NSV) infection of mice causes hindlimb paralysis and 100% mortality in the C57BL/6 mouse strain, while adults of the BALB/cBy mouse strain are resistant to fatal encephalomyelitis. Levels of viral RNA are higher in the brains of infected C57BL/6 mice than in BALB/cBy mice (D. C. Thach et al., J. Virol. 74:6156-6161, 2000). These phenotypic differences between the two strains allowed us to map genetic loci involved in mouse susceptibility to NSV and to find relationships between mortality, paralysis, and viral RNA levels. Analysis of percent mortality in H2-congenic and F(1) mice suggested that the H2 locus, sex linkage, and imprinting were not involved in determining susceptibility and that resistance was partially dominant over susceptibility. Segregation analysis using CXB recombinant inbred (RI) mice indicated that the percent mortality was multigenic. Interval mapping detected a suggestive quantitative trait locus (QTL) on chromosome 2 near marker D2Mit447. Analysis of paralysis in the RI mice detected the same suggestive QTL. Viral RNA level in F(1) mice was intermediate. Interval mapping using viral RNA levels in RI mice detected a significant QTL near marker D2Mit447 that explained 69% of the genetic variance. This QTL was confirmed in F2 mice and was designated as Nsv1. Viral RNA level, percent paralyzed, and percent mortality were linearly correlated (r = 0.8 to 0.9). These results indicate that mortality, paralysis, and viral RNA levels are related complex traits and that Nsv1 controls early viral load and determines the likelihood of paralysis and death.

Surveillance of wild polioviruses in patients with acute flaccid paralysis in Malta during 1998 and 1999

Certification of global poliomyelitis eradication can only be accomplished when all countries have been certified as having achieved wild poliovirus eradication. In order to achieve certification of eradication of poliomyelitis in Malta an active acute flaccid paralysis (AFP) surveillance system comprising the whole population was set up. Surveillance became effective in January 1998. During 1998, there were nine reported cases of AFP (non-polio AFP rate: 2.38 per 100,000 population) two of whom were children under 15 years of age (non-polio AFP rate: 2.52 per 100,000 for the population aged <15 years). In 1999 five cases of AFP were reported (non-polio AFP rate: 1.32 per 100,000 population). One case occurred in a child under 15 years (non-polio AFP rate: 1.28 per 100,000 for population aged <15 years). Virological investigation did not detect any wild or Sabin-like polioviruses.

Multiple cranial nerve palsy in an HIV-positive patient

We report the case of a 32 -year- old HIV-positive Indian male who presented with sixth nerve (bilateral), ninth, tenth and twelfth nerve palsies; cerebellar and posterior column involvement. CT scan showed gyriform enhancement in the right occipital lobe and nodular leptomeningeal enhancement in the left frontal lobe. Cytomegalovirus serology was positive and the patient was treated as presumed CMV. HIV can present with multiple cranial neuropathy and varied neurological involvement.

Virus isolation from saliva and salivary glands of cattle naturally infected with paralytic rabies

The infectivity of saliva, salivary and mammary glands, muscle, lung, kidney and liver of 87 cattle infected with paralytic rabies (positive viral isolation from brains) was studied. Fifty percent dilutions of saliva and tissue samples were inoculated intracerebrally into 10- to 15-day-old mice. Viral isolation in mice was confirmed by direct rabies fluorescent-antibody test and the antigenic variant of the isolates characterized by monoclonal antibodies. Rabies virus was isolated from 4.6% of salivary glands and from 1.6% of saliva samples. The rest of the peripheral tissues were negative. Cerebral and peripheral isolates belonged to vampire-bat antigenic variants. These results indicate that cattle infected by vampire bats may be a source of infection for man. The infection risk would depend on the type of contact between rabid cattle and man.

[Segmental motor paralysis caused by the varicella zoster virus. Clinical study and functional prognosis]

INTRODUCTION

Segmental motor paralysis of the limbs (SMP) complicates 2-3% of the cases of cutaneous herpes zoster. Viral invasion and inflammation of the motor neurons of the anterior horn cells by the varicella-zoster virus (VVZ) causes clinical weakness at the same time and site as the cutaneous eruption.

OBJECTIVES

To analyze the clinical findings, complementary investigations and functional prognosis of patients with SMP at brachial plexus and lumbosacral levels.

PATIENTS AND METHODS

We made a retrospective study of 10 patients with SMP admitted to the Hospital Universitario Gregorio Maranon de Madrid during 1989-1999, aged between 38 and 84 years (6 women, 4 men). Neurological examination was done, including muscle balance, complementary studies including microbiology (serum and CSF serology, viral PCR-ADN), neurophysiology using MNR of the spine and plexuses and functional prognosis on the NDS, NSS and RANKIN scales.

RESULTS

There is a close relationship between dermatome and myotome involvement (90%). The brachial and lumbosacral plexuses were equally affected (50%). Plasma and CSF VVZ serology was positive in 50% of the cases, permitting diagnosis of a patient with no cutaneous lesions (zoster sine herpete). Denervation of the myotomes involved and the paraspinal muscles was shown on neurophysiological studies. In most cases there was functional improvement, with complete functional recovery in 80% of the cases after 12 months.

CONCLUSIONS

VVZ should be considered amongst the aetiologies of SMP, even in the absence of cutaneous lesions (zoster sine herpete). The SMP coincides in time and place with the dermatome lesions. In most patients there is complete functional recovery within 12 months.

Acute flaccid paralysis in infants and young children with enterovirus 71 infection: MR imaging findings and clinical correlates

BACKGROUND AND PURPOSE

Enterovirus 71 (EV71) infection is now considered an important cause of childhood acute flaccid paralysis. The purpose of our study was to determine whether EV71-infection-related acute flaccid paralysis in infants and young children has characteristic MR imaging patterns.

METHODS

Seven infants and young children with acute paralysis of the upper or lower extremities and positive EV71 cultures underwent spinal MR studies during an outbreak of hand-foot-and-mouth disease in Taiwan in 1998.

RESULTS

Acute paralysis was observed in one upper extremity in two patients, in one lower extremity in three patients, and in both lower extremities in two patients. None of the patients had sensory impairment or bulbar palsy. MR studies showed unilateral or bilateral hyperintense lesions in the anterior horn regions of the cord on T2-weighted images in six patients. No abnormal signal was present in one patient. Two of three patients who received intravenous injections of contrast material had ventral root enhancement on T1-weighted images. One of them also had enhancement of the unilateral anterior horn cells. At clinical follow-up, both patients with bilateral anterior horn abnormalities had residual motor weakness, whereas only one of the five patients with unilateral involvement had residual weakness.

CONCLUSION

EV71 radiculomyelitis tends to be unilateral and to specifically involve both the anterior horn cells of the cord and the ventral roots. MR imaging allows early detection of spinal cord and root lesions.

Abortive rabies virus central nervous infection is controlled by T lymphocyte local recruitment and induction of apoptosis

Nonfatal paralysis, induced by the attenuated Pasteur strain of rabies virus, is characterised by local and irreversible flaccid paralysis of the inoculated limbs. We characterised the spread and localisation of virus in the CNS of infected mice, determined the nature of cell injury and examined the role of the immune response. Data indicate that infection of BALB/c mice induced paralysis in 60% of infected mice, the others recovering without sequelae. In both groups of mice, virus was detected in restricted sub-populations of neurons from the brain and spinal cord, and intensity of the neuropathology correlated with levels of rabies RNA and apoptotic infected neurons. However, apoptosis of neurons and paralysis were not due to a direct deleterious effect of the virus, but induced by a T-dependent immune response, as evidenced by their absence in nude mice. Paralysed and asymptomatic mice developed a similar rabies virus-specific IgG2a antibody response, thus excluding the role of any modification of the humoral immune response. In contrast, three events were critically associated with the development of neurological symptoms: the amount of virus in the CNS, the level of apoptosis in both infected neurons and uninfected surrounding cells and the progressive parenchymal infiltration of CD4+ and CD8+ T cells at the site of infection. These data suggest that during nonfatal rabies infection, the levels of viral replication and primary degeneration of infected neurons by apoptosis could be responsible for the infiltration of T lymphocytes capable of inducing secondary degeneration of neural cells.

Natural genetic exchanges between vaccine and wild poliovirus strains in humans

In a previous study of poliovirus vaccine-derived strains isolated from patients with vaccine-associated paralytic poliomyelitis (VAPP) (9, 11), we reported that a high proportion (over 50%) of viruses had a recombinant genome. Most were intertypic vaccine/vaccine recombinants. However, some had restriction fragment length polymorphism (RFLP) profiles different from those of poliovirus vaccine strains. We demonstrate here that five such recombinants, of 88 VAPP strains examined, carried sequences of wild (nonvaccine) origin. To identify the parental wild donor of these sequences, we used RFLP profiles and nucleotide sequencing to look for similarity in the 3D polymerase-coding region of 61 wild, cocirculating poliovirus isolates (43 type 1, 16 type 2, and 2 type 3 isolates). In only one case was the donor identified, and it was a wild type 1 poliovirus. For the other four vaccine/wild recombinants, the wild parent could not be identified. The possibility that the wild sequences were of a non-poliovirus-enterovirus origin could not be excluded. Another vaccine/wild recombinant, isolated in Belarus from a VAPP case, indicated that the poliovirus vaccine/wild recombination is not an isolated phenomenon. We also found wild polioviruses (2 of 15) carrying vaccine-derived sequences in the 3' moiety of their genome. All these results suggest that genetic exchanges with wild poliovirus and perhaps with nonpoliovirus enteroviruses, are also a natural means of evolution for poliovirus vaccine strains.

Contributions of CD8+ T cells and viral spread to demyelinating disease

Acute and chronic demyelination are hallmarks of CNS infection by the neurotropic JHM strain of mouse hepatitis virus. Although infectious virus is cleared by CD8+ T cells, both viral RNA and activated CD8+ T cells remain in the CNS during persistence potentially contributing to pathology. To dissociate immune from virus-mediated determinants initiating and maintaining demyelinating disease, mice were infected with two attenuated viral variants differing in a hypervariable region of the spike protein. Despite similar viral replication and tropism, one infection was marked by extensive demyelination and paralysis, whereas the other resulted in no clinical symptoms and minimal neuropathology. Mononuclear cells from either infected brain exhibited virus specific ex vivo cytolytic activity, which was rapidly lost during viral clearance. As revealed by class I tetramer technology the paralytic variant was superior in inducing specific CD8+ T cells during the acute disease. However, after infectious virus was cleared, twice as many virus-specific IFN-gamma-secreting CD8+ T cells were recovered from the brains of asymptomatic mice compared with mice undergoing demyelination, suggesting that IFN-gamma ameliorates rather than perpetuates JHM strain of mouse hepatitis virus-induced demyelination. The present data thus indicate that in immunocompetent mice, effector CD8+ T cells control infection without mediating either clinical disease or demyelination. In contrast, demyelination correlated with early and sustained infection of the spinal cord. Rapid viral spread, attributed to determinants within the spike protein and possibly perpetuated by suboptimal CD8+ T cell effector function, thus ultimately leads to the process of immune-mediated demyelination.

[Velopharyngeal palsy: a case report]

Here we present a case of velopharyngeal palsy. An 18-year-old man had hyperemia in his left conjunctivum. One or two weeks later he experienced nasal speech and difficulty in swallowing. General physical examination was normal. The only abnormal neurological finding was palato-pharyngeal paralysis on the right side. MRI of the head and neck had no abnormalities. Acute and convalescent sera showed no rise in viral antibody titer. CSF examination was normal except for the increased IgG% and IgG.albumin index. Treatment consisted of glycerol and steroid, and his symptom improved within two or three weeks. We think immunological mechanism is important because CSF examination showed increased IgG% and IgG.albumin index in our case. Acquired and isolated velopharyngeal palsy is uncommon. Only 26 cases have been reported so far. This is the first case in Japan. The disease has some characteristics. This occurs in childhood and adolescence. Onset is sudden, consisting in rhinolalia and dysphagia. On examination there is asymmetry of the pharynx and deviation of the uvula contralateral to the affected side. There is no other neurological abnormalities. Complete spontaneous recovery is usual. In some cases viral infection is the cause, but in most cases the cause is unknown. In contrast, the disease with both acquired velopharyngeal palsy and vocal cord palsy is relatively common. This occurs in the middle aged or elderly people. In addition to dysphagia and hoarse voice, this disease often accompanies neurological abnormalities such as other cranial nerve palsy and meningitis, fever, and pain in the pharyngeal region. In most cases viral infection is the cause.

Molecular evolution of oral poliovirus vaccine strains during multiplication in humans and possible implications for global eradication of poliovirus

The oral poliovirus vaccine (OPV) has been effectively used in the control of poliomyelitis and in the eradication of wild polioviruses. Although there are many advantages in using attenuated OPV strains in the campaign to eradicate poliomyelitis, several studies have demonstrated that there are some disadvantages such as (a) excretion by vaccines of OPV-derived polioviruses with genomic modifications known to increase the neurovirulence, (b) appearance of vaccine-associated paralytic poliomyelitis (VAPP) and other adverse effects in vaccinees, (c) occurrence of persistent infections caused by OPV-derived strains in immunodeficient patients with VAPP, (d) transmission of OPV-derived polioviruses to susceptible individuals which develop VAPP, and (e) detection of OPV-derived polioviruses in the environment, which could be a source of infection for humans in the future. Different studies indicate that it is important to consider the possibility of persistent infections and excretion of OPV-derived polioviruses for long periods by humans, and also the survival in the environment of OPV-derived polioviruses excreted by humans, which could be transmitted and circulate in a non-immune population after stopping poliovirus vaccination. The findings reported here may have important implications for global poliomyelitis eradication initiative and indicate that surveillance of OPV-derived strains will also be important in the final step of eradication of poliomyelitis from the planet.