Abstract
In the complex microenvironment of the human respiratory tract, different kinds of microorganisms may synergistically interact with each other resulting in viral-bacterial co-infections that are often associated with more severe diseases than the respective mono-infections. Human respiratory paramyxoviruses, for example parainfluenza virus type 3 (HPIV3), are common causes of respiratory diseases both in infants and a subset of adults. HPIV3 recognizes sialic acid (SA)-containing receptors on host cells. In contrast to human influenza viruses which have a preference for α2,6-linked sialic acid, HPIV3 preferentially recognize α2,3-linked sialic acids. Group B streptococci (GBS) are colonizers in the human respiratory tract. They contain a capsular polysaccharide with terminal sialic acid residues in an α2,3-linkage. In the present study, we report that HPIV3 can recognize the α2,3-linked sialic acids present on GBS. The interaction was evident not only by the binding of virions to GBS in a co-sedimentation assay, but also in the GBS binding to HPIV3-infected cells. While co-infection by GBS and HPIV3 had a delaying effect on the virus replication, it enhanced GBS adherence to virus-infected cells. To show that other human paramyxoviruses are also able to recognize the capsular sialic acid of GBS we demonstrate that GBS attaches in a sialic acid-dependent way to transfected BHK cells expressing the HN protein of mumps virus (MuV) on their surface. Overall, our results reveal a new type of synergism in the co-infection by respiratory pathogens, which is based on the recognition of α2,3-linked sialic acids. This interaction between human paramyxoviruses and GBS enhances the bacterial adherence to airway cells and thus may result in more severe disease.
Highlights
Human parainfluenza viruses (HPIV) were first isolated in the late 1950s from children sick with lower respiratory diseases
We have recently shown that the α2,3-linked sialic acids on the capsular polysaccharide of Group B streptococci (GBS) are recognized by several avian influenza viruses but not by human and porcine influenza viruses that have a preference for the α2,6-linkage type (Cundell and Tuomanen, 1994; Strohal et al, 1994; Tong et al, 2018)
In a co-sedimentation experiment, HPIV3 was incubated for 1 h with either GBS or, as a control, with S. suis
Summary
Human parainfluenza viruses (HPIV) were first isolated in the late 1950s from children sick with lower respiratory diseases. HPIV3 and some other viruses of the family Paramyxoviridae share the common feature of recognizing sialic acid (SA)containing receptors on host cells (Suzuki et al, 2001, 2004). The hemagglutinin-neuraminidase (HN) protein and the fusion (F) protein, are involved in the initial steps of viral-cell interactions (Moscona and Peluso, 1992; Porotto et al, 2007). HPIV3, the clinically most prevalent HPIV subtype, recognizes α2,3-linked sialic acids in branched and unbranched oligosaccharides present on either glycoproteins or glycolipids (Suzuki et al, 2001). With respect to the sialic acid binding activity, the human paramyxoviruses HPIV3 and MuV differ from human influenza viruses which have a clear preference for the α2,6 linkage (Rogers and Paulson, 1983)
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