For cvb3, recruitment of immune cells in the brain was evidenced by animal experiments ..
Furthermore, previous studies showed that increased levels of il-6, ifn , and il-1 in cerebrospinal fluid (csf) are observed in patients with pulmonary edema ..
Currently, our knowledge about the host neuronal cells of neurotropic enteroviruses is based on the data collected from animal experiments and autopsy cases that provide clues to elucidate their possible cns target cells ..
Different enteroviruses target different areas of the nervous system. It has been proposed that an enterovirus infection caused apoptosis process functions in a cell-dependent manner ..
Furthermore, a poliovirus infection can increase cytosolic calcium concentrations in imr5 cells, which may be related to pv-induced apoptosis upon cvb infection, significant apoptosis and productive virus replication were observed in mouse cortical neurons ..
We noted that many neurotropic enteroviruses such as cvb and ev71 are capable of infecting neural progenitor cells and actively replicating in these cells ..
In patients with post-polio syndrome, poliovirus rna can be detected in cerebral spinal fluid years after the primary infection. Based on a comparison of the induced apoptotic process in non-neuronal and neuronal cell lines, abl kinase is activated only in neuronal cells and may play an essential role in mediating ev71 induced neuronal apoptosis. Intriguingly, although ev-d68 is an emerging enterovirus that may cause polio-like syndromes in young children, magnetic resonance imaging (mri) results showed that there is no enhancing lesion in either the gray matter of the spinal cord or the brainstem upon ev-d68 infection identification of the natural targeted neuronal cells of enteroviruses is limited by the accessibility of human specimens thus, most studies are performed using neuroblastoma and glioblastoma cells.
Although the cns has been considered to be an immunologically privileged area, immune responses could be evoked in response to an enterovirus infection. In summary, the viral receptors not only determine cell tropism but may also contribute to the transport of virions. We noted that many neurotropic enteroviruses such as cvb and ev71 are capable of infecting neural progenitor cells and actively replicating in these cells.
This finding provides evidence that il-1 can be up-regulated in the cns. Chen demonstrated that ev71 transmitted into the nervous system occurs primarily via the retrograde axonal transport route in mice. Upon stimulation with a poliovirus antigen, the production of ifn- was produced and could be measured in whole blood.
In addition, other non-polio enteroviruses accounted for approximately one half of aseptic meningitis cases in children. These viruses are replicated in the gastrointestinal tract first and then disseminated to other organstissues via specific pathways. Several receptors that are responsible for ev71 entry have been characterized.
Meningitis that is caused by virus infections occurs often in children. Thus, ev71 has been considered as an important pathogen for afp. Thus, the infiltrated immune cells in the cns may serve as sources for ifn- secretion.
Therefore, a virus may mimic the ligand of car and promote the endocytosis of viral particles. The authors were supported by the following grants cmrpd 1d0311-3 and cmrpd 1e0401-3 (shin-ru shih). However, the mechanisms about the effects of il-6 in ev71-related neuropathogenesis are not clear. Receptors mediate the entry of viruses into the host cells and, thus, play essential roles in cell tropism. Nevertheless, viral infection causes apoptosis of infected neural progenitors and then results in the loss of these cells, which may contribute to the enteroviral infection-associated long-term sequelae such as learning deficits and impaired recognition.
Meningitis that is caused by virus infections occurs often in children. Intracerebral infection of neonatal mice with echovirus type 1 (ev1) results in paralysis of the hindlimbs. Coxsackievirus, poliovirus, and ev71 have been demonstrated to induce encephalitis in infected patients. The cns is primarily composed of neural lineage cells including neurons, astrocytes, and oligodendrocytes and non-neural cells, such as endothelial cells and microglia cells. However, other viruses such as poliovirus and enterovirus 71 (ev71) have also been demonstrated to have the ability to evoke aseptic meningitis.
Through intensive studies, many enterovirus receptors have been identified. Thus, the infiltrated immune cells in the cns may serve as sources for ifn- secretion. This genus consists of 12 species that include enteroviruses a to j and rhinoviruses a to c. In addition to the poliovirus receptor-dependent retrograde axonal transport pathway, it has been proposed that poliovirus can efficiently reach the cns in a receptor-independent axonal transport process. In addition to daf, coxsackievirus uses other receptor such as coxsackievirus and adenovirus receptor (car) to infect the target cells.
Interestingly, car may directly link to the endocytic pathway in motor neurons demonstrated that car ligands can trigger car-car disengagement, promoting internalization. The existence of cytokineschemokines is associated with inflammation and may contribute to long-term sequelae. Since ifn- is capable of increasing vascular permeability, it is likely to contribute to ev71-caused pathogenesis. This review focused on the recent advances of enteroviruses with regard to cns infections and the factors that contribute to their pathogenesis. Over a long course of evolution, host cells use immune system to control the infection and viruses develop various strategies to evade cellular defense mechanisms. Furthermore, virus particle binding with receptors on the endothelial cells is able to induce activation of a protein phosphatase to facilitate virus entry. Since the primary human neuronal and glial cells are difficult to obtain, most studies have been performed using neuroblastoma and glioblastoma cell lines. The concentration of csf il-1 is significantly higher in patients who suffered from ev71-induced pulmonary edema. Thus, further studies need to be performed to confirm the association of ev persistent infection and these diseases. In an ev71 mouse model, autophagy could be detected in the brain tissues of infected mice and was implicated in facilitating viral replication.quently, encephalitis, denoting infection or inflammation of the brain parenchyma .... festations of infections with the nonpolio enteroviruses or the West Nile ...