Chapter 29: Negative-Strand RNA Viruses

Negative-Strand RNA Viruses overview delves into the biology and clinical significance of negative-strand RNA viruses, a group of enveloped pathogens that must carry their own RNA-dependent RNA polymerase to initiate infection by synthesizing messenger RNA. The discussion begins with the Rhabdoviridae family, specifically the rabies virus, a bullet-shaped pathogen known for its zoonotic transmission and its ability to travel through the nervous system to the brain. Once in the central nervous system, it causes fatal encephalitis characterized by the development of Negri bodies. The Paramyxoviridae family is also explored, featuring pathogens such as the mumps virus, which triggers parotitis, and the measles virus, identified by its diagnostic Koplik spots and potential for severe complications like encephalitis. This family also includes the respiratory syncytial virus (RSV), the leading cause of bronchiolitis and pneumonia in infants. A significant portion of the chapter focuses on the Orthomyxoviridae, or influenza viruses, which are unique because their segmented genomes replicate within the host cell nucleus. The text explains the mechanisms of antigenic drift and antigenic shift, the latter of which involves the reassortment of genetic segments between different strains to create novel viruses capable of causing global pandemics. The discussion further examines the Filoviridae family, containing the Ebola and Marburg viruses, which are associated with high-mortality hemorrhagic fevers and visceral organ damage. Additionally, the Bunyaviridae and Arenaviridae families are detailed, highlighting their transmission through arthropod vectors or rodent excreta and their roles in causing conditions ranging from encephalitis to Lassa fever. Throughout the chapter, emphasis is placed on diagnostic methods like RT-PCR and ELISA, the importance of specific vaccinations for prevention, and the use of antiviral therapies such as neuraminidase inhibitors to manage seasonal outbreaks.