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The simultaneous transmission of chikungunya virus (CHIKV) and dengue viruses (DENV) has been a major public health concern because of their sympatric distribution and shared mosquito vectors. Groups of Aedes aegypti (L.) and Aedes albopictus (Skuse) were orally infected with 1.5 × 10(5) PFU/ml of CHIKV and 3.2 × 10(6) FFU/ml of DENV-2 simultaneously or separately in inverse orders and evaluated for dissemination and transmission by qRT-PCR. Simultaneous dissemination of both viruses was detected for all groups in Ae. aegypti and Ae. albopictus while cotransmission of CHIKV and DENV-2 only occurred at low rates after sequential but not simultaneous infection.

The Flavivirus genus is in the family Flaviviridae and is comprised of more than 70 viruses. These viruses have a broad geographic range, circulating on every continent except Antarctica. Mosquito-borne flaviviruses, such as yellow fever virus, dengue virus serotypes 1–4, Japanese encephalitis virus, and West Nile virus are responsible for significant human morbidity and mortality in affected regions. This review focuses on what is known about flavivirus-mosquito interactions and presents key data collected from the field and laboratory-based molecular and ultrastructural evaluations.

The Bunyaviridae family is comprised of more than 350 viruses, of which many within the Hantavirus, Orthobunyavirus, Nairovirus, Tospovirus, and Phlebovirus genera are significant human or agricultural pathogens. The viruses within the Orthobunyavirus, Nairovirus, and Phlebovirus genera are transmitted by hematophagous arthropods, such as mosquitoes, midges, flies, and ticks, and their associated arthropods not only serve as vectors but also as virus reservoirs in many cases. This review presents an overview of several important emerging or re-emerging bunyaviruses and describes what is known about bunyavirus-vector interactions based on epidemiological, ultrastructural, and genetic studies of members of this virus family.

Background: Millions of human infections caused by arthropod-borne pathogens are initiated by the feeding of an infected mosquito on a vertebrate. However, interactions between the viruses and the mosquito vector, which facilitates successful infection and transmission of virus to a subsequent vertebrate host, are still not fully understood. Finding: Here we describe early chikungunya virus (CHIKV) infectious events in cells derived from one of the most important CHIKV vectors, Aedes albopictus. We demonstrated that CHIKV infection of mosquito cells depended on acidification of the endosome as indicated by significant inhibition following prophylactic treatment with the lysosomotropic drugs chloroquine, ammonium chloride, and monensin, which is consistent with observations in mammalian cells. While all three agents inhibited CHIKV infection in C6/36 cells, ammonium chloride was less toxic to cells than the other agents. Conclusion: The observation of similar mechanisms for inhibition of CHIKV infection in mosquito and mammalian cell lines suggests that conserved entry pathways are utilized by CHIKV for vertebrate and invertebrate cell types.

Arthropod-borne viruses (arboviruses) may infect and replicate in haematophagus insects and arachnids when the arthropods take a bloodmeal from an infected vertebrate. Following an appropriate incubation period, the arthropod may transmit the amplified virus to susceptible vertebrates when the arthropod takes a subsequent bloodmeal. Of more than 500 recognised arboviruses, almost 100 cause a wide variety of illnesses in humans, livestock, and/or wildlife species ranging from subclinical infection to mild febrile disease, haemorrhagic fever, encephalitis or death. Arboviruses have wide geographic distributions which are largely dependent upon their vectors, and different arboviruses can be found on all continents including Antarctica. Since very few specific antiviral therapies or arbovirus vaccines exist, control focuses primarily on vector elimination and education on arthropod avoidance. Arbovirus prevalence has increased dramatically during the past 3 decades, with viral emergence and re-emergence driven by urbanisation, increased international travel and commercial transportation, and expanding vector distribution. Key Concepts: Arboviruses infect and replicate in insects and ticks and may be transmitted during blood feeding to susceptible vertebrates, including humans. ‘Arbovirus’ is an ecological term, and the recognised arboviruses are found in the families Togaviridae, Flaviviridae, Bunyaviridae, Orthomyxoviridae, Rhabdoviridae, Reoviridae, and Asfarviridae. Most arboviruses are single-stranded RNA viruses. Infection with an arbovirus may be asymptomatic or may cause fever, haemorrhage, encephalitis, with or without sequelae and death. Currently licensed human vaccines only exist for yellow fever virus (YFV), Japanese encephalitis virus (JEV) and tick-borne encephalitis virus (TBEV). Arbovirus prevalence in specific regions fluctuates, but emergence and re-emergence has caused an increase in human infections over the past 30 years. Keywords: arboviruses; arthropods; fever; rash; encephalitis; haemorrhagic