Morphological demonstration of the virus of tick-borne encephalitis in the human brain

Advances in rapid point-of-care virus testing

Outbreaks of viral diseases seriously jeopardize people's health and cause huge economic losses. At the same time, virology provides a new perspective for biology, molecular biology and cancer research, and it is important to study the discovered viruses with potential applications. Therefore, the development of immediate and rapid viral detection methods for the prevention and treatment of viral diseases as well as the study of viruses has attracted extensive attention from scientists. With the continuous progress of science and technology, especially in the field of bioanalysis, a series of new detection techniques have been applied to the on-site rapid detection of viruses, which has become a powerful approach for human beings to fight against viruses. In this paper, the latest research progress of rapid point-of-care detection of viral nucleic acids, antigens and antibodies is presented. In addition, the advantages and disadvantages of these technologies are discussed from the perspective of practical application requirements. Finally, the problems and challenges faced by rapid viral detection methods and their development prospects are discussed.

A comprehensive neurological perspective on tick-borne flaviviruses, with emphasis on Powassan virus

Powassan virus (POWV), a tick-borne flavivirus transmitted primarily by Ixodes ticks, poses a significant threat as it can lead to severe neuroinvasive illness. This review delves into the nuanced clinical presentation of Powassan infection, a challenge in diagnosis exacerbated by the absence of an available vaccine. Over the past decade, the prevalence of POWV has surged in North America, necessitating a thorough examination of its neurological manifestations alongside tick-borne encephalitis virus (TBEV). A comprehensive literature search conducted up to January 2024 revealed 135 cases of neurological symptoms associated with either Powassan or TBEV infection. Notably, severe occipital headache emerged as the most prevalent symptom (22.75%), followed by meningoencephalitis (10.34%), seizures (8.27%), and flaccid paresis (6.8%). Additional manifestations included poor balance, wide gait, dysarthria, facial nerve palsy, seizure, slurred speech, and absent deep tendon reflexes. Tragically, nine cases resulted in fatal outcomes attributed to POWV infection. This analysis highlights the intricate spectrum of neurological symptoms associated with Powassan infection and underscores the necessity for heightened awareness among medical practitioners, particularly in regions with a higher prevalence of the virus. The complexity of symptoms emphasizes the need for further research to unravel the factors contributing to this diversity. Additionally, exploring potential treatment avenues and vaccine development is crucial in addressing the rising threat posed by POWV, ultimately enhancing our ability to manage and prevent severe neurological outcomes.

Encephalitic Arboviruses: Emergence, Clinical Presentation, and Neuropathogenesis

Arboviruses are arthropod-borne viruses that exhibit worldwide distribution, contributing to systemic and neurologic infections in a variety of geographical locations. Arboviruses are transmitted to vertebral hosts during blood feedings by mosquitoes, ticks, biting flies, mites, and nits. While the majority of arboviral infections do not lead to neuroinvasive forms of disease, they are among the most severe infectious risks to the health of the human central nervous system. The neurologic diseases caused by arboviruses include meningitis, encephalitis, myelitis, encephalomyelitis, neuritis, and myositis in which virus- and immune-mediated injury may lead to severe, persisting neurologic deficits or death. Here we will review the major families of emerging arboviruses that cause neurologic infections, their neuropathogenesis and host neuroimmunologic responses, and current strategies for treatment and prevention of neurologic infections they cause.

Impact of direct virus-induced neuronal dysfunction and immunological damage on the progression of flavivirus (Modoc) encephalitis in a murine model

Flavivirus encephalitis is believed to be the result of two main mechanisms: (i) direct damage to and dysfunction of neurons as a result of viral replication and (ii) destruction of the brain tissue by an inflammatory response. The differential impact of both mechanisms on the progression of flavivirus encephalitis has not been clearly determined. We have now studied the encephalitis caused by Modoc virus (MODV) infection in (i) severe combined immunodeficiency (SCID) mice, (ii) immunocompetent NMRI mice, and (iii) NMRI mice under varying immunosuppressive treatment regimens. In SCID mice, Modoc virus infection proved to be uniformly lethal (100%). The virus replicated extensively in neurons and no signs of inflammation of the brain were observed. In immunocompetent NMRI mice, intranasal (but not intraperitoneal) inoculation with MODV caused severe encephalitis accompanied by a fulminate inflammatory response. When NMRI mice, infected with MODV via the intraperitoneal route, were submitted to a brief immunosuppressive treatment, they also developed encephalitis with an obvious inflammatory component. These animals died significantly earlier than NMRI mice, which received immunosuppressive treatment for a longer period of time. In the latter group, no signs of inflammation of the brain were noted. These models thus allow us to distinguish between the impact of direct viral replication and that of immunological factors in the development of MODV encephalitis, and let us to conclude that (i) replication of the virus in neurons is sufficient to cause fatal encephalitis and (ii) immunological factors contribute significantly to disease progression.

Contribution to the histology of tick-borne encephalitis

The light microscopic changes of the first human case in which electron microscopic identification of the virus was successful, are described. They are compared with the findings accepted in the literature as characteristic of tick-borne encephalitis. Although meningeal and intracerebral infiltrations were partly connected, the process cannot be regarded as a meningoencephalitis. The choroid plexus remained free from infiltration. The discontinuous inflammatory process was severe in the cerebral cortex in the pre-central region, further in the temporal lobe, and became even more accentuated in the amygdaloid nucleus. Reduction in the number of nerve cells could be ascertained chiefly in the motor cortex. The tick-borne encephalitis belongs to the group of disseminated polioencephalitides with predilection site in the brain stem, all of them caused by ribonucleic acid viruses, irrespective of whether the virus belongs to the families of Picorna-, Toga-, or Rhabdoviruses. Within this histologically outlined group the individual entities possess distinctive traits. The significance of the anoxic-vasal factor in the process formation is displayed on the instance of some traits of the histological pictures.