VIRAL SHAPES. VIRUSES There are presently 20 recognized families of viruses that affect humans and/or animals CLASSIFIED BY: –By whether they contain.

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Presentation transcript:

VIRAL SHAPES

VIRUSES There are presently 20 recognized families of viruses that affect humans and/or animals CLASSIFIED BY: –By whether they contain DNA or RNA –By structure –Also by type of capsid and or envelope

Viral Vocabulary The CAPSID = the protein shell that encloses the (DNA or RNA). ENVELOPE may contain material from the host cell as well as the virus

Bacteriophage Bacteriophage = A virus that infects bacteria

Viral Replication

Lytic vs. Lysogenic

Lytic – “Fast & Furious” 4 Stages: 1.Penetration: DNA or RNA injected into host cell 2.Biosynthesis: Virus has hijacked the host cell uses it to make copies of itself 3.Maturation: puts the viral pieces back together 4.Lysis: cell membrane breaks open and releases virus

Lysogenic – “Slow & Steady” Integration of DNA/RNA into hosts bacterium’s genome (chromosome) When virus copies itself – new genetic material is copied also – then it can convert to the lytic cycle This is how viruses mutate

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DNA VIRUSES The following are a few of the more common DNA Viruses

Adenovirus

Adenoviruses Cause colds Conjunctivitis ("pink eye")

HPV - Papillomavirus Often causes warts Warts may go away spontaneously Human genital warts may become malignant if they last for a long time.

Herpesvirus Seven different species are known to infect humans –Including herpes simplex virus (HSV) –Cytomegalovirus (CMV) –Zoster (VZV); and –Epstein Barr virus (EBV)

Hepatitis B Virus

Hepatitis B Can be acute or chronic It can last for up to several months in acute infections Many years (even for life) in chronic infections.

RNA Viruses

Influenza virus

Rotavirus Intestine – causes diarrhea, especially in children. The term "rota", meaning wheel

Paramyxoviruses measlesmumpsencephalitis

VIRAL CLASSIFICATION - review RNA or DNA Retrovirus single-stranded or double- stranded shape enveloped or not

A couple of “strange bugs” Hard to classify …

Rickettsia These organisms are small Pleomorphic (can change shape) coccobacilli Their structure similar to Gram-negative bacteria

Rickettsia

Mycoplasmas Mycoplasma are the smallest organisms lacking cell walls that are capable of self- replication Seven different species infect humans Pneumonia for example

H1N1

1918 Flu Killer Flu Spanish Flu

Killed somewhere between 20 – 50 million; infected 500 million

Viral Hemorrhagic Viruses Ebola

Ebola hemorrhagic fever The Ebola virus was first identified in Sudan and in a nearby region of Zaire (now Democratic Republic of the Congo) in Ebola is one of the most virulent (deadly) viral diseases known to humankind, causing death in 50-90% of victims cases.

Ebola The Ebola virus is transmitted by direct contact with the blood, body fluids and tissues of infected persons. Transmission of the Ebola virus has also occurred by handling ill or dead infected chimpanzees.

Ebola outbreak contained in Uganda 22 February 2008 (article from WHO) In November 2007: the Ministry of Health in Uganda confirmed an outbreak of Ebola in Bundibugyo. In all, 149 cases were detected and 37 patients died.

CDC – Ebola - Current Case Counts: 14-west-africa/case-counts.html 14-west-africa/case-counts.html 14-west-africa/case-counts.html