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Taxonomy of Paramyxoviridae : Classification and Characteristics

Introduction

Paramyxoviridae is a family of enveloped, negative-sense, single-stranded RNA viruses known to infect humans, animals, and birds. Many members of this family are highly pathogenic, causing respiratory, neurological, and systemic diseases. Notable viruses within this family include measles virus, mumps virus, and respiratory syncytial virus (RSV). Understanding the taxonomy of Paramyxoviridae is essential for epidemiology, vaccine development, and disease control.

Classification of Paramyxoviridae

The family Paramyxoviridae is classified under the order Mononegavirales, which includes other RNA virus families like Rhabdoviridae and Filoviridae.

Subfamilies and Genera

The Paramyxoviridae family is divided into two subfamilies:

  1. Paramyxovirinae – Primarily infects mammals and birds.
  2. Avulavirinae – Mostly infects birds.

Each subfamily is further divided into several genera:

Genomic and Structural Characteristics

Genome Organization

Paramyxoviruses have a non-segmented, negative-sense, single-stranded RNA genome (~15-19 kb in length). The genome encodes essential structural and non-structural proteins:

  • Nucleocapsid (N) protein – Protects the viral RNA.
  • Phosphoprotein (P) and Large (L) protein – Form the RNA-dependent RNA polymerase complex.
  • Matrix (M) protein – Maintains viral structure.
  • Fusion (F) and Hemagglutinin-Neuraminidase (HN) or Glycoprotein (G) proteins – Facilitate viral entry and cell attachment.

Virion Structure

  • Enveloped viruses with pleomorphic shape.
  • Surface glycoproteins mediate host cell attachment and entry.
  • Helical nucleocapsid enclosed within a lipid bilayer derived from the host cell membrane.