topic 4 protozoa and other infectious agents

Acellular infectious agents

are “non-cellular” entities that contain some cellular material that can contaminate and affect living cells.

Virology

study of viruses

genome type and their manner of mRNA production.

The Baltimore classification classifies viruses based on the

seven

Currently, viruses are classified into ___ groups based on strandedness (+ or -), type (RNA or DNA), and number of strands (double or single stranded)

Poxviridae

Orthopoxvirus (Smallpox, Cowpox, Mpox)

Herpesviridae

HSV (herpes)

Papillomaviridae

HPVs (warts and cervical cancer)

Rhabdoviridae

Lyssavirus (Rabies)

Flaviviridae

Flavivirus (Dengue, Zika, yellow fever)

Picornaviridae

Rhinovirus (common colds) - Poliovirus (poliomyelitis)

Orthomyxoviridae

Alpha-, Beta-, Gamma-, Deltainfluenzavirus (flu viruses)

Coronaviridae

SARS-CoV - MERS-CoV

Retroviridae

Lentivirus (HIV)

lytic phase

results in the lysis of the host cell

lysogenic phase

happens when the virus is capable of integrating its nucleic acid to its host’s genome.

Transduction

is the virus-mediated transfer of DNA into cells.

prion

is a protein that can trigger a normal protein to fold abnormally ● In mammals, it primarily affects the brain and neural tissues.

viroids

are small, single stranded circular RNAs that are infectious pathogens. ● All known viroids inhabit plants particularly angiosperms.

Virusoids

are similar to viroid but they depend on viruses (helper virus) for replication. They need to co-infect for them to be able to access a cell. ● They are also called satellite RNAs.

Protozoa

- is a polyphyletic group of unicellular or colonial, eukaryotic free-living or parasitic, heterotrophic microorganisms. ● They were previously referred to as “one-celled” animals.

Protozoa

They fall under Kingdom Protista lumped together with algae, dinoflagellates and slime molds ● They are neither plants nor animals.

Free-living protozoa

are phagotrophic microorganisms.

Amoebas

are generally classified as free-living but there are a few species that are known to be pathogenic to humans such as Entamoeba histolytica and Naegleria fowleri