büt paramyoxoviruses adn orthomyoxoviruses

Paramyxoviruses general characteristics

Single-stranded, negative-sense RNA; envelope contains glycoprotein fusion activity; replicates in the cytoplasm; does not undergo genetic reassortment; buds from plasma membrane.

Mumps virus clinical signs

Paramyxovirus highly seen in kids 5-9; detected via RT-PCR; causes swollen salivary/parotid glands, swollen cheeks, and meningitis; spreads to testes, ovaries, and pancreas; prevented by live vaccine.

Measles (Rubeola) clinical signs

Paramyxovirus with 8-15 day incubation; spreads via respiratory droplets; causes Koplik spots (small white ulcerations on buccal mucosa) and maculopapular rash starting on the face and spreading downward.

Measles complications

Subacute Sclerosing Panencephalitis (SSPE): neurologic deterioration at ~9 years old showing high titers of measles antibody in cerebrospinal fluid.

Measles, Mumps, Rubella Vaccines

Measles: live virus, single serotype, shouldn't be given before 15 months. Rubella: prevents reinfection and dissemination. Mumps: live vaccine.

Parainfluenza virus

Paramyxovirus; causes barking cough and infects respiratory epithelium; reinfection is common because secretory IgA is short-lived.

Respiratory Syncytial Virus (RSV)

Paramyxovirus lacking hemagglutinin; causes severe lower respiratory tract disease requiring hospitalization (e.g., in 3-year-old child).

Rubella (German Measles)

Starts with a mild fever followed by a rash the same day; Congenital Rubella Syndrome is commonly associated with deafness.

Adenoviruses

Double-stranded DNA; spread via respiratory/fecal-oral routes; causes conjunctivitis and pharyngitis.

Orthomyxoviruses general characteristics

Segmented RNA virus; replicates in the nucleus; surface proteins include Hemagglutinin (H) for attachment and Neuraminidase (N) for release.

Antigenic Drift

Minor mutations (H and N) causing seasonal influenza; seen in Influenza A and B; results in new subtypes over time; explains need for annual flu vaccine.

Antigenic Shift

Major reassortment of RNA segments requiring a segmented genome; causes pandemics; seen ONLY in Influenza A (happens in pigs, horses, birds).

Influenza Types A, B, C

Type A: Infects humans and animals, causes pandemics. Type B: Infects humans only, causes epidemics. Type C: Causes mild disease.