RESUMEN
Bunyaviruses are members of the Bunyavirales order, which is the largest group of RNA viruses, comprising 12 families, including a large group of emerging and re-emerging viruses. These viruses can infect a wide variety of species worldwide, such as arthropods, protozoans, plants, animals, and humans, and pose substantial threats to the public. In view of the fact that a better understanding of the life cycle of a highly pathogenic virus is often a precondition for developing vaccines and antivirals, it is urgent to develop powerful tools to unravel the molecular basis of the pathogenesis. However, biosafety level -3 or even -4 containment laboratory is considered as a necessary condition for working with a number of bunyaviruses, which has hampered various studies. Reverse genetics systems, including minigenome (MG), infectious virus-like particle (iVLP), and infectious full-length clone (IFLC) systems, are capable of recapitulating some or all steps of the viral replication cycle; among these, the MG and iVLP systems have been very convenient and effective tools, allowing researchers to manipulate the genome segments of pathogenic viruses at lower biocontainment to investigate the viral genome transcription, replication, virus entry, and budding. The IFLC system is generally developed based on the MG or iVLP systems, which have facilitated the generation of recombinant infectious viruses. The MG, iVLP, and IFLC systems have been successfully developed for some important bunyaviruses and have been widely employed as powerful tools to investigate the viral replication cycle, virus-host interactions, virus pathogenesis, and virus evolutionary process. The majority of bunyaviruses is generally enveloped negative-strand RNA viruses with two to six genome segments, of which the viruses with bipartite and tripartite genome segments have mostly been characterized. This review aimed to summarize current knowledge on reverse genetic studies of representative bunyaviruses causing severe diseases in humans and animals, which will contribute to the better understanding of the bunyavirus replication cycle and provide some hints for developing designed antivirals.
RESUMEN
OBJECTIVES: In vivo lung perfusion (IVLP) is an emergent strategy to treat lung metastases because it allows localized delivery of chemotherapy with minimal systemic exposure. Previously, short-term (± 30 minutes) IVLP resulted in variable efficacy and significant lung toxicity. We hypothesize that a modified IVLP strategy derived from an ex vivo lung perfusion technique could minimize lung injury. Our objective was to demonstrate the feasibility and safety of a modified prolonged (4 hours) IVLP. METHODS: Six Yorkshire pigs were used for the experiments. A thoracotomy was performed, the left pulmonary artery and pulmonary veins were cannulated, and the left lung was isolated in situ. IVLP was performed at normothermia for 4 hours using Steen Solution (XVIVO Perfusion, Göteburg, Sweden) as perfusate. The flow rate was 16% of estimated cardiac output and left atrial pressure was maintained between 3 and 5 mm Hg. Perfusate was deoxygenated and supplied with CO2 to physiologic levels before entering the lungs. A protective mode of ventilation was used. After IVLP, the left lung was allowed to reperfuse for additional 4 hours. Airway dynamics, gas exchange, and pulmonary vascular resistance were used to assess left lung physiology. Histologic signs of lung injury were assessed before and after IVLP, and 4 hours after reperfusion. RESULTS: Lung function parameters were stable throughout the 4-hour IVLP and during reperfusion. No significant histologic evidence of acute lung injury was observed. CONCLUSIONS: Four hours of IVLP is feasible without adding significant lung injury. Prolonged perfusion time and a protective protocol might provide safer and more efficacious treatment of pulmonary metastases.