Vaccinia Virus Entry, Exit, and Interaction with Differentiated Human Airway Epithelia

Abstract

Variola virus, the causative agent of smallpox, enters and exits the host via the respiratory route. To better understand the pathogenesis of poxvirus infection and its interaction with respiratory epithelia, we used vaccinia virus and examined its interaction with primary cultures of well-differentiated human airway epithelia. We found that vaccinia virus preferentially infected the epithelia through the basolateral membrane and released viral progeny across the apical membrane. Despite infection and virus production, epithelia retained tight junctions, transepithelial electrical conductance, and a steep transepithelial concentration gradient of virus, indicating integrity of the epithelial barrier. In fact, during the first four days of infection, epithelial height and cell number increased. These morphological changes and maintenance of epithelial integrity required vaccinia virus growth factor, which was released basolaterally, where it activated epidermal growth factor 1 receptors. These data suggest a complex interaction between the virus and differentiated airway epithelia; the virus preferentially enters the cells basolaterally, exits apically, and maintains epithelial integrity by stimulating growth factor receptors.The threat of bioterrorism has raised concern that smallpox could reemerge as a significant disease entity (10,21,46). The large population of unvaccinated individuals, the many immunocompromised people, and the lack of good treatments suggest that variola virus, the causative agent of smallpox, has the potential for extensive and rapid spread. Thus, there is a renewed interest in understanding poxvirus pathogenesis.Variola virus infection occurs following the inhalation of virus-laden airborne droplets (7, 12, 13a, 34). Virus replication within the lung and lymphoid system is followed by viremia (16,41,57). Patients remain asymptomatic during the 7-to 17-daylong incubation period, after which symptoms develop, including fever, malaise, and head and body aches, followed by oropharyngeal lesions and skin rash 2 to 4 days later. Sloughing of oropharyngeal lesions and respiratory tract release discharge infectious viral particles into the air, perpetuating human-tohuman spread (14, 27, 52). The high mortality rate associated with smallpox results from the overwhelming toxemia leading to respiratory and/or cardiac failure. These observations indicate that infection involves viral entry and exit through the oropharyngeal-respiratory route and suggest that the airways may play a key role in the viral life cycle.Because of the risks of experiments using variola virus, the limitations and difficulties associated with studies of nonhuman animals, and insufficient clinical information from humans, much of our knowledge about the interaction between poxvirus and the host has come from studies using vaccinia virus and cultured cells. Vaccinia virus is the orthopoxvirus used for immunization against smallpox, and it is widely substituted for variola virus in the investigation of poxvirus biology (20,28,4...

Polarized Entry of Human Parechoviruses in the Airway Epithelium

“…In contrast to what has been established previously for several respiratory viruses such as influenza virus, rhinovirus (RV), coronavirus, or respiratory syncytial virus (RSV) (Matrosovich et al, 2004;Johnson et al, 2015;Griggs et al, 2017), HPeVs infected airway epithelium more efficiently from the basolateral rather than the apical surface. Similarly, basolateral entry in the HAE cultures has been reported for vaccinia virus, reovirus, some adeno-and arenaviruses and measles virus (Sinn et al, 2002;Vermeer et al, 2007;Dylla et al, 2008;Excoffon et al, 2008;Lütschg et al, 2011). In line with our HPeV data, vaccinia, reo-, and measles viruses also exhibited apical shedding of the progeny virions (Sinn et al, 2002;Vermeer et al, 2007;Excoffon et al, 2008).…”

“…Similarly, basolateral entry in the HAE cultures has been reported for vaccinia virus, reovirus, some adeno-and arenaviruses and measles virus (Sinn et al, 2002;Vermeer et al, 2007;Dylla et al, 2008;Excoffon et al, 2008;Lütschg et al, 2011). In line with our HPeV data, vaccinia, reo-, and measles viruses also exhibited apical shedding of the progeny virions (Sinn et al, 2002;Vermeer et al, 2007;Excoffon et al, 2008). We found that both HPeV1 and HPeV3 targeted the p63+ basal cells for replication.…”

Skin Viral Infections: Host Antiviral Innate Immunity and Viral Immune Evasion

“…VACV replication preferentially occurs in cutaneous sites with compromised barrier function ( 39 ), where there is increased access to the basolateral membrane ( 40 ). Viral entry begins with attachment of four viral proteins (A26, A27, D8 and H3) of the mature virion to cell surface glycosaminoglycans (GAGs), extracellular matrix proteins, and, at lipid rafts, integrin membrane receptors ( 41 , 42 ).…”

ABCF1 regulates dsDNA-induced immune responses in human airway epithelial cells

“…These results limited the use of ISD as dsDNA challenge stimulus in human airway epithelial cells for studying ABCF1 function. Vaccinia virus is a dsDNA virus that is able to infect airway epithelial cells (19)(20)(21)(22)(23). We therefore determined the response of human airway epithelial cells to VACV-70, a 70bp dsDNA oligonucleotide containing Vaccinia virus motifs (51).…”

“…Like RNA viruses, adenovirus is able to infect airway epithelium followed by replication, which leads to a variety of innate immune defences able to sense viral nucleic acids and proteins (14,17,18). Vaccinia virus is another dsDNA virus that is able to infect airway epithelium and has been explored for capacity to genetically engineer the virus for transgene delivery, vaccination strategies, and studying Variola virus infections (19)(20)(21)(22)(23). Exploring how the airway epithelium responds to viruses may provide new strategies for controlling infections, optimizing transgene delivery, and vaccination strategies relevant in lung health and disease.…”