Pox Viruses and Parvoviruses PDF

Pox Viruses & Parvoviruses Masika Moses Objectives General viral characteristics & morphology Pathogenesis Clinical features Treatment & Prevention Small Pox Monkeypox virus Parvovirus B19 Poxviruses Large & complex viruses Infect humans and animals Typically prese...

Pox Viruses & Parvoviruses Masika Moses Objectives General viral characteristics & morphology Pathogenesis Clinical features Treatment & Prevention Small Pox Monkeypox virus Parvovirus B19 Poxviruses Large & complex viruses Infect humans and animals Typically present with skin lesions Transmitted though inhalation or contact with infected animals, humans or contaminated fomites Examples: Small pox – Eradicated Monkeypox Molluscum contagiosum Viral characteristics Large complex virions (200 nm diameter) Brick or oval shape Enveloped (NB: mature virions also infectious) Linear, non-segmented, dsDNA, 200 kb Codes for over 100 polypeptides with different functions Replicate in the cytoplasm 4 Taxonomy Family Poxviridae Four genera (out of 22) infect humans Genera Examples Orthopoxvirus Variola, Monkeypox, Camelpox, Cowpox, Vaccinia Molluscipoxvirus Molluscum contagiosum Yatapoxvirus Tanapox Parapoxvirus Orf virus, Pseudocowpox virus Monkeypox Virus Structure Structure of enveloped extracellular virions (EEV) and intracellular mature virions (IMV) 6 https://www.mdpi.com/1422-0067/23/14/7866/htm Poxvirus on EM  Replication Poxviruses replicate in the cytoplasm ▶They carry a DNA-dependent RNA polymerase to enable this Entry: Fusion or macropinocytosis Early-phase: Promoters of viral replication Intermediate phase: Replication enzymes Late-phase: Structural proteins Exit through: Lysis, exocytosis & extrusion (actin tail assembly) Monkeypox Virus Belongs to orthopoxvirus genus (same to Small pox) First identified in 1958 in monkeys, hence the name Natural host is most likely rodents First human case detected in DR Congo in 1970 Endemic in Central & west Africa Few isolated cases outside Africa until 2022 outbreak ▶ thousands of cases globally Monkeypox Distribution Jul 2022 Nov 2022 77,000 cases 36 deaths 110 Countries Source: Monkeypox: A New Threat? https://www.mdpi.com/1422-0067/23/14/7866/htm  Monkeypox Transmission NEJM Review Article. Monkeypox https://www.nejm.org/doi/full/10.1056/NEJM ra2208860 Monkeypox clades Has two clades: 1. Central African/Congo Basin Clade: Reported in DR Congo & South Sudan More virulent with higher mortality rate (10%) 2. West African Clade Has 95-99% sequence homology with C. African clade Reported in Nigeria, other west African countries Cause of the ongoing global pandemic Mortality rate is