Predominant kidney involvement in a fatal case of hantavirus pulmonary syndrome caused by Sin Nombre virus

Orthohantavirus Pathogenesis and Cell Tropism

Orthohantaviruses are zoonotic viruses that are naturally maintained by persistent infection in specific reservoir species. Although these viruses mainly circulate among rodents worldwide, spill-over infection to humans occurs. Orthohantavirus infection in humans can result in two distinct clinical outcomes: hemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS). While both syndromes develop following respiratory transmission and are associated with multi-organ failure and high mortality rates, little is known about the mechanisms that result in these distinct clinical outcomes. Therefore, it is important to identify which cell types and tissues play a role in the differential development of pathogenesis in humans. Here, we review current knowledge on cell tropism and its role in pathogenesis during orthohantavirus infection in humans and reservoir rodents. Orthohantaviruses predominantly infect microvascular endothelial cells (ECs) of a variety of organs (lungs, heart, kidney, liver, and spleen) in humans. However, in this review we demonstrate that other cell types (e.g., macrophages, dendritic cells, and tubular epithelium) are infected as well and may play a role in the early steps in pathogenesis. A key driver for pathogenesis is increased vascular permeability, which can be direct effect of viral infection in ECs or result of an imbalanced immune response in an attempt to clear the virus. Future studies should focus on the role of identifying how infection of organ-specific endothelial cells as well as other cell types contribute to pathogenesis.

Meeting report: Eleventh International Conference on Hantaviruses

The 2019 11th International Conference on Hantaviruses (ICH 2019) was organized by the International Society for Hantaviruses (ISH), and held on September 1-4, 2019, at the Irish College, in Leuven, Belgium. These ICHs have been held every three years since 1989. ICH 2019 was attended by 158 participants from 33 countries. The current report summarizes research presented on all aspects of hantavirology: ecology; pathogenesis and immune responses; virus phylogeny, replication and morphogenesis; epidemiology; vaccines, therapeutics and prevention; and clinical aspects and diagnosis.

More novel hantaviruses and diversifying reservoir hosts--time for development of reservoir-derived cell culture models?

Due to novel, improved and high-throughput detection methods, there is a plethora of newly identified viruses within the genus Hantavirus. Furthermore, reservoir host species are increasingly recognized besides representatives of the order Rodentia, now including members of the mammalian orders Soricomorpha/Eulipotyphla and Chiroptera. Despite the great interest created by emerging zoonotic viruses, there is still a gross lack of in vitro models, which reflect the exclusive host adaptation of most zoonotic viruses. The usually narrow host range and genetic diversity of hantaviruses make them an exciting candidate for studying virus-host interactions on a cellular level. To do so, well-characterized reservoir cell lines covering a wide range of bat, insectivore and rodent species are essential. Most currently available cell culture models display a heterologous virus-host relationship and are therefore only of limited value. Here, we review the recently established approaches to generate reservoir-derived cell culture models for the in vitro study of virus-host interactions. These successfully used model systems almost exclusively originate from bats and bat-borne viruses other than hantaviruses. Therefore we propose a parallel approach for research on rodent- and insectivore-borne hantaviruses, taking the generation of novel rodent and insectivore cell lines from wildlife species into account. These cell lines would be also valuable for studies on further rodent-borne viruses, such as orthopox- and arenaviruses.

A global perspective on hantavirus ecology, epidemiology, and disease

Hantaviruses are enzootic viruses that maintain persistent infections in their rodent hosts without apparent disease symptoms. The spillover of these viruses to humans can lead to one of two serious illnesses, hantavirus pulmonary syndrome and hemorrhagic fever with renal syndrome. In recent years, there has been an improved understanding of the epidemiology, pathogenesis, and natural history of these viruses following an increase in the number of outbreaks in the Americas. In this review, current concepts regarding the ecology of and disease associated with these serious human pathogens are presented. Priorities for future research suggest an integration of the ecology and evolution of these and other host-virus ecosystems through modeling and hypothesis-driven research with the risk of emergence, host switching/spillover, and disease transmission to humans.

Community acquired pneumonia in the tropics

PURPOSE OF REVIEW

Due to the exponential growth of international exchange, millions of travelers are exposed to respiratory pathogens in the tropics and may return ill. Community-acquired pneumonia is one of the more prevalent infections.

RECENT FINDINGS

The acquisition of infections in the tropics, including community-acquired pneumonias, has been described for several centuries. During recent decades some microorganisms have been disclosed as causative of the disease (Legionella pneumophila in 1976 and hantavirus in 1990); other microorganisms are real new pathogens that were not previously demonstrated to have a pathogenic role in humans (e.g. severe acute respiratory syndrome coronavirus producing an outbreak in 2003 and H5N1 avian influenza virus producing an increasing number of human cases over the last few years).

SUMMARY

A number of microorganisms may produce pneumonia in people who live or have traveled to tropical zones. History, including geography and epidemiology, physical exam and complementary workout are precious tools for the diagnosis, therapy and prevention. Exposure to microorganisms in tropical areas may show different patterns. A high index of suspicion, detailed investigation of travel, exposure history of the patient, and a basic understanding of the incubation periods and distribution of the various potential pathogens are imperative for the diagnosis.

Síndrome pulmonar e cardiovascular por hantavírus

A síndrome pulmonar e cardiovascular por hantavírus é uma doença de conhecimento relativamente recente e freqüentemente fatal, apresentando-se como síndrome do desconforto respiratório agudo. No Brasil, desde o primeiro surto, relatado em novembro/dezembro de 1993, em Juquitiba, 226 casos já foram registrados pela Fundação Nacional da Saúde. A doença afeta indivíduos previamente hígidos, apresentando-se com pródromo febril e sintomas semelhantes aos de um resfriado comum, podendo rapidamente evoluir para edema pulmonar, insuficiência respiratória aguda e choque. A hemoconcentração e a plaquetopenia são comuns da síndrome pulmonar e cardiovascular por hantavírus, e o quadro radiológico típico é de um infiltrado intersticial bilateral difuso, que progride rapidamente para consolidações alveolares, paralelamente à piora do quadro clínico. A mortalidade inicial era em torno de 75% e declinou para aproximadamente 35%, nos últimos anos. Os pacientes que sobrevivem geralmente recuperam-se completamente, cerca de uma semana após o estabelecimento do quadro respiratório. O agente causal, não reconhecido até há pouco, foi identificado como um hantavírus, cujo reservatório natural são animais roedores da família Muridae, subfamília Sigmodontinae. O tratamento específico antiviral ainda não é bem estabelecido, estando em estudo a eficácia de ribavirina. Cuidados de terapia intensiva como ventilação mecânica e monitoramento hemodinâmico invasivo são necessários nas formas mais graves da doença. Essas medidas, se instituídas precocemente, podem melhorar o prognóstico e a sobrevida dos pacientes com síndrome pulmonar e cardiovascular por hantavírus.