RESUMO
Eastern and Venezuelan equine encephalitis viruses (EEEV and VEEV, respectively) cause severe morbidity and mortality in equines and humans. Like other mosquito-borne viruses, VEEV infects dendritic cells (DCs) and macrophages in lymphoid tissues, fueling a serum viremia and facilitating neuroinvasion. In contrast, EEEV replicates poorly in lymphoid tissues, preferentially infecting osteoblasts. Here, we demonstrate that infectivity of EEEV for myeloid lineage cells including DCs and macrophages was dramatically reduced compared to that of VEEV, whereas both viruses replicated efficiently in mesenchymal lineage cells such as osteoblasts and fibroblasts. We determined that EEEV infection of myeloid lineage cells was restricted after attachment, entry, and uncoating of the genome. Using replicon particles and translation reporter RNAs, we found that translation of incoming EEEV genomes was almost completely inhibited in myeloid, but not mesenchymal, lineage cells. Alpha/beta interferon (IFN-alpha/beta) responses did not mediate the restriction, as infectivity was not restored in the absence of double-stranded RNA-dependent protein kinase, RNase L, or IFN-alpha/beta receptor-mediated signaling. We confirmed these observations in vivo, demonstrating that EEEV is compromised in its ability to replicate within lymphoid tissues, whereas VEEV does so efficiently. The altered tropism of EEEV correlated with an almost complete avoidance of serum IFN-alpha/beta induction in vivo, which may allow EEEV to evade the host's innate immune responses and thereby enhance neurovirulence. Taken together, our data indicate that inhibition of genome translation restricts EEEV infectivity for myeloid but not mesenchymal lineage cells in vitro and in vivo. In this regard, the tropisms of EEEV and VEEV differ dramatically, likely contributing to observed differences in disease etiology.
Assuntos
Células Dendríticas/virologia , Vírus da Encefalite Equina do Leste/crescimento & desenvolvimento , Vírus da Encefalite Equina Venezuelana/crescimento & desenvolvimento , Macrófagos/virologia , Animais , Linhagem Celular , Células Cultivadas , Cricetinae , Encefalomielite Equina/virologia , Encefalomielite Equina Venezuelana/virologia , Fibroblastos/virologia , Interferon-alfa/sangue , Interferon beta/sangue , Camundongos , Osteoblastos/virologia , Biossíntese de Proteínas , Análise de Sobrevida , Proteínas Virais/biossínteseRESUMO
Goat's serum was used to prepare primary cultures of fibroblast from chicken embryo and hamster kidney. Later they were inoculated the East equine encephalomyelitis virus, being compared with culture from calf's serum. The choice of goat's serum is of great interest for the development of scientific research and national economy.
Assuntos
Meios de Cultura , Cabras/sangue , Animais , Bovinos/sangue , Células Cultivadas , Embrião de Galinha , Cricetinae , Vírus da Encefalite Equina do Leste/crescimento & desenvolvimento , Fibroblastos/citologia , Rim , Macaca mulatta , Cultura de Vírus/métodosRESUMO
Human peripheral blood leukocytes (PBL) were examined for their ability to support growth of several group A arboviruses in vitro. Cells were refractory to infection with eastern (EEE) and western (WEE) equine encephalitis viruses, whereas Venezuelan equine encephalomyelitis (VEE) virus was shown to infect and replicate to a substantially high titer. When PBL were fractionated into purified subpopulations, only the monocytes were susceptible to predictive VEE virus infection. Lymphocytes treated 24 h before virus inoculation with phytohemagglutinin (10 microgram/ml) were capable of propagating significant amounts of VEE virus. A monocytic cell line, J-111, was also susceptible to infection with VEE, EEE, and WEE viruses, whereas a lymphocytic cell line, Raji, was refractory. Additional information on the participation of PBL during human infection with these viruses may add considerably to our understanding of their differing pathogenicities and clinical pictures.