MBL structurally contains a type II-like collagenous domain and a carbohydrate recognition domain (CRD). We have recently generated three novel recombinant chimeric lectins (RCL), in which varying length of collagenous domain of mannose-binding lectin (MBL) is replaced with that of L-ficolin (L-FCN). CRD of MBL is used for target recognition because it has a broad spectrum in pathogen recognition compared with L-FCN. Results of our study demonstrate that these RCLs are potent inhibitors of influenza A virus (IAV). RCLs, against IAV, show dosedependent activation of the lectin complement pathway, which is significantly higher than that of recombinant human MBL (rMBL). This activity is observed even without MBL-associated serine proteases (MASPs, provided by MBL deficient mouse sera), which have been thought to mediate complement activation. These observations suggest that RCLs are more efficient in associating with MASP-2, which predominantly mediates the activity. Yet, additional serum further increases the activity while RCL-mediated coagulation-like enzyme activities are diminished compared with rMBL, suggesting reduced association with MASP-1, which has been shown to mediate coagulation-like activity. These data suggest that RCLs may interfere less with host coagulation, which is advantageous to be a therapeutic drug. Importantly, these RCLs have surpassed rMBL for anti-viral activities, such as viral aggregation, reduction of viral hemagglutination (HA) and inhibition of virus-mediated HA and neuraminidase (NA) activities. These results are encouraging * Address correspondence to: Kazue Takahashi, PhD, 55 Fruit Street, GRJ1402, Boston, MA 02114. Fax: 617-724-3248;, ktakahashi1@partners.org. ¶ Co-first authors. All authors have no financial conflict.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access

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IntroductionProstacyclin is a critical mediator of structure and function in the pulmonary circulation, causing both the inhibition of vascular smooth muscle growth and vasodilatation via the stimulation ofadenylate cyclase. To examine the potential role ofalterations in prostacyclin production or mechanism of action in chronic hypoxic pulmonary hypertension, we determined the effects of prolonged (7 d Hypoxic pulmonary hypertension is one of the critical mechanisms underlying persistent pulmonary hypertension ofthe neonate and the development of pulmonary hypertension in older children and adults with a variety of cardiac and respiratory illnesses (1, 2). This phenomenon has been well studied in the adult rat, yielding both physiologic and anatomic findings similar to those noted in the human (3-5). In the rat model, pulmonary hypertension is evident almost immediately after the onset of acute severe hypoxia, and it is also present with accompanying anatomic changes after more prolonged periods of hypoxia of milder degree. These events in the pulmonary circulation of the rat are contrasted by the maintenance of normal systemic blood pressure, mimicking the clinical experience with this problem (1, 4, 6, 7). Studies in the rat and other species indicate that locally-produced prostacyclin is important in the regulation ofvasomotor tone and vascular cell differentiation and growth in the pulmonary circulation (8, 9). These actions are mediated through the plasma membrane-bound enzyme adenylate cyclase, with prostacyclin stimulation of cyclic AMP (cAMP) production resulting in vasodilatation and the inhibition ofsmooth muscle cell growth (10, 1 1). In vivo experiments and in vitro studies with perfused isolated lung preparations have demonstrated that pulmonary production ofthis potent vasodilator increases with acute hypoxia, resulting in a degree of attenuation of the vasoconstrictor response (12,13). However, despite the initial increase in prostacyclin production, further hypoxia leads to the development of pulmonary hypertension with medial hypertrophy of muscular arteries and extension of vascular smooth muscle (VSM)' into peripheral, normally nonmuscular, arteries (3, 4). These alterations are prevented in the rat when angiotensin II is administered during the hypoxia period, most likely related to its ability to release prostaglandins (PG) (8). This suggests that changes in PG synthesis or PG-mediated mechanisms may be involved in the pathogenesis of chronic hypoxic pulmonary hypertension.To examine the potential role ofalterations in prostacyclin production or mechanism ofaction in chronic hypoxic pulmonary hypertension, we determined the effects ofprolonged (7 d) in vivo hypoxia on in vitro prostacyclin production and mediation of adenylate cyclase activity in rat main pulmonary arteries. PGE2 production and mediation ofadenylate cyclase activity were also investigated to determine if the results for prostacyclin are specific to that vasodilatory prostanoid. Based on the findings with acute hypox...