This document summarizes different DNA and RNA viruses. For DNA viruses, it describes the structure, transmission, disease caused, diagnosis and prevention of adenoviruses, hepadnaviruses, herpesviruses, papillomaviruses, polyomaviruses, parvoviruses and poxviruses. For RNA viruses, it discusses the arenaviruses, bunyaviruses, calciviruses, coronaviruses, filoviruses, flaviviruses, orthomyxoviruses, paramyxoviruses, picornaviruses and their characteristics. It provides a detailed overview of the key viral families and genera that infect humans.

1. DNA viruses

2. A. Adenoviridae
1. Adenoviruses:
• Transmission:
• Respiratory, fecal-oral, and direct contact (eye).
• Site of latency:
• Replication in oropharynx.
• Disease:
• Acute respiratory disease, Pharyngitis, pharyngoconjunctival fever,
keratoconjunctivitis, pneumonia, hemorrhagic cystitis, disseminated disease, and
gastroenteritis in children.
• Diagnosis:
• Cell culture (HEp-2 and other continuous human epithelial lines), enzyme
immunoassay (EIA) for gastroenteritis serotypes 40-41.
• Prevention:
• Vaccine (adenovirus serotypes 4 and 7) for military recruits.
• Note:
• Adenoviruses has a role as vectors in gene therapy, deliver DNA for gene
replacement therapy in few genetic disorders, such as cystic fibrosis.
• Non-enveloped. All DNA viruses replicate in the nucleus, except Poxvirus which
replicate in the cytoplasm.
• The only viruses having a fiber protruding from each of the 12 vertices of the capsid.

3. B. Hepadnaviridae
(Hepadnavirus)
1. Hepatitis B virus (HBV):
• Transmission:
• Humans are reservoir and vector; spread by direct contact, including exchange of body
secretions, recipient of contaminated blood products, percutaneous injection of virus, and
perinatal exposure.
• Site of latency:
• Liver.
• Disease:
• Acute infection with resolution (90%); fulminant hepatitis, most coinfected with delta
virus (1%); chronic hepatitis, persistence of hepatitis B surface antigen (HBsAg) (9%)
followed by resolution (disappearance of HBsAg), asymptomatic carrier state, chronic
persistent (systemic disease without progressive liver disease), or chronic active disease
(progressive liver damage). Liver cirrhosis.
• Oncogenic Liver cancer.
• Diagnosis:
• Serology, viral antigen detection, and polymerase chain reaction (PCR). AST, ALT and
Bilirubin.
• Prevention:
• HBV vaccine; hepatitis B immune globulin.
• Note: Enveloped virus.

4. Australian antigen (HBsAg)

5. C. Herpesviridae
(Herpesvirus (HSV), enveloped)
1. HSV-1 and HSV-2:
Transmission: direct contact with infected secretions.
Site of latency Sensory nerve ganglia.
• Disease: predominant virus in parentheses: gingivostomatitis (HSV-
1), pharyngitis (HSV-1), herpes labialis (HSV-1), genital infection
(HSV-2), conjunctivitis (HSV-1), keratitis (HSV-1), herpetic whitlow
(HSV-1 and HSV-2), encephalitis (HSV-1 in adults), disseminated
disease (HSV-1 or HSV-2 in neonates).
• Detection: cell culture (HDF, others), EIA, FA stain, IH stain, PCR.
2. Varicella zoster virus (VZV):
• Transmission: close personal contact, especially respiratory.
• Site of latency: dorsal root ganglia.
• Disease: chicken pox (varicella), shingles (zoster),a belt of roses
from Hell.
• Detection: FA stain, cell culture (HDF), shell vial culture, PCR.
• Prevention: Vaccine.

6. 3. Epstein–Barr virus (EBV):
• Transmission:
• Close contact with infected saliva.
• Site of latency:
• B lymphocytes.
• Disease:
• Infectious mononucleosis, progressive lymphoreticular disease, oral hairy
leukoplakia in patients with HIV.
• Oncogenic Burkitt lymphoma, nasopharyngeal carcinoma.
• Detection:
• Serology, Paul–Bunnell (heterophil Ab test-IgM), Monospot test (RBCs are more
specific for acute infectious mononucleosis heterophile antibodies), PCR.

7. 4. Cytomegalovirus (CMV):
• Transmission: close contact with infected secretions, blood transfusions (WBCs), organ
transplants, transplacental.
• Site of latency WBCs, endothelial cells, cells in a variety of organs.
• Disease: Asymptomatic infection, congenital disease of newborn, symptomatic disease of
immunocompromised host (pneumonia), heterophile-negative infectious mononucleosis.
• Diagnosis: Cell culture (HDF), shell vial culture, CMV antigenemia, FA stain, PCR.
5. HHV-6 and HHV-7:
• Transmission: Most likely close contact via respiratory route; almost all children
infected by age 2-3 years.
• Site of latency: T lymphocytes (CD4 cells).
• Disease: Roseola (exanthem subitum), fever, malaise, rash, leukopenia, and interstitial
pneumonitis in organ transplant recipients.
• Detection: detection of virus in peripheral blood specimens by PCR, cell culture using
lymphocyte lines.
6. HHV-8:
• Transmission: Not known; much less widely disseminated than other herpes viruses.
• Site of latency: Viral genome found in Kaposi tumor cells, endothelial cells, and tumor-
infiltrating leukocytes.
• Disease: Kaposi sarcoma.
• Detection: PCR or in situ by hybridization.

9. D. Papovaviridae
Papillomavirus
1. Human papilloma virus (HPV):
• Transmission:
• Direct contact, sexual contact for genital warts.
• Site of latency:
• Epithelial tissue.
• Disease:
• Papilloma: benign tumors of squamous cells or skin and genital warts, benign
head and neck tumours, anogenital warts.
• Diagnosis:
• Cytology, DNA probes.
• Oncogenic:
• Cervical and penile cancer (especially HPV types 16 and 18).
• Note:
• Non-enveloped.

10. E. Polyomaviridae
Polyomavirus
1. Polyomavirus (BK virus [BKV] and JC virus [JCV] infect humans).
• Transmission:
• Probably direct contact with infected respiratory secretions; both viruses are
ubiquitous in humans.
• Site of latency:
• Kidney.
• Disease:
• Mild or asymptomatic primary infection; virus remains dormant in kidneys;
reactivation in immunocompromised patients causes hemorrhagic cystitis (BKV)
or progressive multifocal leukoencephalopathy (JCV).
• Detection:
• JCV by polymerase chain reaction (PCR) (cerebrospinal fluid) or electron
microscopy (EM) (brain tissue); BKV by PCR or cytology (urine).
• Note:
• Non-enveloped.

11. F. Parvoviridae
Parvovirus
1. Parvovirus B-19:
• Transmission:
Close contact, probably respiratory.
• Disease:
• Erythema infectiosum (fifth disease), aplastic crises
in patients with chronic hemolytic anemias
(ertyhrovirus), and fetal infection and stillbirth.
• Detection:
• Serology, polymerase chain reaction (PCR), histology.
• Note:
• The smallest of the DNA. Non-enveloped.

12. G. Poxviridae
Poxviruses
1. Smallpox (Variola), molluscum contagiosum, Orf, and
monkeypox viruses:
• Transmission:
• Respiratory droplets (smallpox); direct contact
(molluscum contagiosum, Orf, monkeypox).
• Disease:
• All are diseases of the skin; smallpox is a generalized
infection with pustular rash (10%-25% fatal);
molluscum contagiosum manifests as benign nodules;
Orf manifests as localized papules/vesicles;
monkeypox manifests as a generalized infection that
includes the skin.
• Detection:
• Electron microscopy (EM) of material from a skin
lesion; polymerase chain reaction (PCR).
• Prevention:
• Vaccine for smallpox; avoid contact for all viruses.
• Note:
• The largest and most complex viruses.

13. RNA viruses

14. A. Arenaviridae
Arenaviruses
• Transmission:
• From rodent to human through contamination of human
environment with rodent urine; virus enters through skin abrasions
or inhalation.
• Disease:
• LCM causes asymptomatic to influenza like to aseptic meningitis–
type disease; Lassa fever virus causes influenza-like disease to
severe haemorrhagic fever.
• Diagnosis:
• Serology, polymerase chain reaction.
• Note:
• Enveloped.
• Pleomorphic, Sandy appearance.
• All RNA viruses replicate in cytoplasm, except Orthomyxoviruses
and Retroviruses that have replicative stages in nuclei.

15. Bunyaviridae
Bunyavirus, Hantavirus, Nairovirus, and
Phlebovirus.
• Transmission:
• Mosquito (Aedes), tick, and sandfly vectors, except for hantaviruses, which are
zoonoses transmitted by contact with rodent host and/or their excretions.
• Disease:
• Encephalitis for arboviruses; pneumonia or hemorrhagic fever for hantaviruses.
• Phlebovirus: Rift Valley fever (RVF).
• Diagnosis:
• Serology and antibody detection in cerebrospinal fluid, reverse transcriptase
polymerase chain reaction (RT-PCR) for hantaviruses (serology [IgM and IgG]) also
available for hantavirus (sin nombre virus).
• Note:
• Triple-segmented and a single-stranded RNA.
• Enevloped.
• All these viruses, with the exception of hantaviruses, are arboviruses that are
transmitted by mosquitoes, ticks, and flies.
• Hantaviruses, transmitted by rodents.

17. Calciviridae
Calciviruses
Norovirus (Norwalk virus)
• Transmission:
• Fecal-oral.
• Disease:
• Nausea, vomiting, and diarrhoea.
• Norwalk, most common cause viral gastroenteritis in adults.
• The infection typically occurs in group settings, such as schools, hospitals, nursing
homes.
• Diagnosis:
• EM, RT-PCR, EIA for noroviruses.
• Note:
• Naked nonenveloped viruses.

18. Coronaviridae
Coronaviruses
• Transmission:
• Probably direct contact or aerosol.
• Disease:
• Common cold; possibly gastroenteritis, especially in children; Severe acute respiratory
syndrome (SARS).
• Diagnosis:
• EM, RT-PCR.
• Note:
• Crown-like appearance. Enveloped.
• The second most important cause of the common cold; rhinoviruses being the first
cause.

19. Filoviridae
Filoviruses
(Ebola virus and Marburg virus)
• Transmission:
• Transmissible to humans from monkeys and,
presumably, other wild animals; human-to-
human transmission via body fluids and
respiratory droplets.
• Disease:
• Severe haemorrhage and liver necrosis;
mortality as high as 90%.
• The most pathogenic of the haemorrhagic fever
viruses.
• Diagnosis:
• Electron microscopy, cell culture in monkey
kidney cells; Biosafety Level 4 required.
• RT-PCR, ELISA.
• Note:
• Filo: threadlike. Enveloped.
• Marburg hemorrhagic fever virus displays the
characteristic “shepherd’s hook” morphology.

20. Flaviviridae
Flaviviruses
(yellow fever virus, dengue virus,
and St. Louis encephalitis virus), arboviruses.
Hepatitis C virus (HCV).
• Transmission:
• Arthropod vector, usually mosquito.
• Disease:
• St. Louis and West Nile encephalitis, dengue and yellow fever.
• Jaundice.
• Diagnosis:
• Serology and antibody detection in cerebrospinal fluid; reverse transcriptase
polymerase chain reaction (RT-PCR) for dengue and yellow fever.
• Note:
• Enveloped.

21. Hepatitis C virus (HCV)
• Transmission:
• Parenteral, blood donation, perinatal, or sexual.
• Disease:
• Acute and chronic hepatitis; strong correlation between chronic HCV infection and
hepatocellular carcinoma.
• Liver cirrhosis.
• Diagnosis:
• Serology, RT-PCR, and viral genotyping.
• Recombinant immunoblot assay (RIBA) using recombinant HCV antigen is a highly
specific test to detect HCV infection. Also NAAT (RNA).
• Note:
• The most important cause of parenteral non-A, non-B hepatitis (NANBH)
worldwide.

22. Hepiviridae
Hepevirus
HEV
• Transmission:
• Fecal-oral.
• Disease:
• Hepatitis similar to that caused by hepatitis A virus except for extraordinarily
high case fatality rate (10%-20%) among pregnant women.
• Diagnosis:
• Serology.
• Note:
• Previously classified in the family of caliciviruses.
• Non-enveloped.

23. Orthomyxoviridae
Orthomyxovirus
1. Influenza A:
• Transmission:
• Contact with respiratory secretions.
• Disease:
• Influenza (fever, malaise, headache, myalgia, cough); primary influenza
pneumonia; in children, bronchiolitis, croup, otitis media.
• Detection:
• Cell culture (PMK), EIA, FA stain, RT-PCR.
• Epidemiology:
• Viral subtypes based on hemagglutinin and neuraminidase glycoproteins
abbreviated “H” and “N,” respectively (e.g., H1N1 or H3N2); infects humans and
other animals; antigenic drift, resulting in minor antigenic change, causes local
outbreaks of influenza every 1-3 years; antigenic shift, resulting in major
antigenic change, causes periodic worldwide outbreaks.
• Prevention:
• Influenza vaccine or antiviral prophylaxis.

24. 2. Influenza B:
• Transmission:
• Contact with respiratory secretions.
• Disease:
• Similar to “mild” influenza.
• Detection:
• Cell culture (PMK), EIA, FA stain, RT-PCR.
• Epidemiology:
• Antigenic drift only, resulting in local outbreaks every 1-3 years.
• Prevention:
• Influenza vaccine or antiviral prophylaxis.
3. Influenza C:
• Transmission:
• Contact with respiratory secretions.
• Disease:
• Mild form of influenza causing URTIs.
• Detection:
• Testing not routinely requested, so virus is infrequently detected; only valid test
is NAAT.
• Epidemiology:
• Most cases occur in children; occurs sporadically or as localized outbreaks.

25. Paramyxoviridae
Paramyxoviruses
1. Measles virus:
• Transmission:
• Contact with respiratory secretions; extremely contagious.
• Disease:
• Measles, atypical measles (occurs in those with waning vaccine immunity), and
subacute sclerosing panencephalitis.
• Detection:
• Cell culture (PMK) and serology.
• Prevention:
• Measles vaccine.
2. Mumps virus:
• Transmission:
• Person-to-person contact, presumably respiratory droplets.
• Disease:
• Mumps.
• Detection:
• Cell culture (PMK) and serology.
• Prevention:
• Mumps vaccine.

26. 3. Parainfluenza virus:
• Transmission:
• Contact with respiratory secretions.
• Disease:
• Adults: upper respiratory disease, rarely pneumonia, Children: respiratory
including croup, bronchiolitis, and pneumonia.
• Detection:
• Cell culture (PMK), shell vial culture, and FA stain.
4. Respiratory syncytial virus (RSV):
• Transmission:
• Person-to-person by hand and respiratory contact.
• Disease:
• Primarily in infants and children. Infants: bronchiolitis, pneumonia, and croup.
Children: upper respiratory disease.
• Detection:
• Cell culture (HEp-2), EIA, and FA stain.
• Epidemiology:
• Disease occurs annually late fall through early spring; nosocomial transmission
can occur readily.

27. Picornaviridae
Picornaviruses
• Picornaviruses (pico: small) are the smallest viruses, measuring 20–30 nm in size.
They are nonenveloped.
1. Enteroviruses
2. Poliovirus (3 types)
3. Coxsackie virus, group A (23 types)
4. Coxsackie virus, group B (6 types)
5. Echovirus (31 types)
• Transmission:
• Fecal-oral.
• Disease:
• Predominant virus in parentheses: polio (poliovirus); herpangina (coxsackie A);
pleurodynia (coxsackie B); aseptic meningitis (many enterovirus types);
handfoot-mouth disease (coxsackie A); pericarditis and myocarditis (coxsackie
B); acute hemorrhagic conjunctivitis (enterovirus 70); and fever, myalgia,
summer “flu” (many enterovirus types), neonatal disease (echoviruses and
coxsackie viruses).
• Detection:
• Cell culture (PMK and HDF), PCR, and serology.
• Prevention:
• Avoid contact with virus; vaccination for polio.

29. 6. Hepatitis A virus (enterovirus type 72):
Transmission:
• Fecal-oral.
• Disease:
• Acute hepatitis with short incubation, abrupt
onset, and low mortality; no carrier state.
• Detection:
• Serology. LFT.
• Prevention:
• Vaccine; prevent clinical illness with serum
immunoglobulin.
7. Rhinovirus (common cold virus):
• Transmission:
• Contact with respiratory secretions.
• Disease:
• Common cold.
• Detection:
• Cell culture (usually not clinically necessary), RT-
PCR.

30. Reoviridae
Reovirus
Rotavirus
• Transmission:
• Fecal-oral; survives well on inanimate objects.
• Disease:
• Gastroenteritis in infants and children 6 months to 2 years.
• Detection:
• Enzyme immunoassay (EIA), latex agglutination (LA).
• Prevention:
• Avoid contact with virus; vaccination.

31. Retroviridae
Retroviruses
1. Human immunodeficiency virus types 1 and 2 (HIV-1, HIV-2).
• Transmission: Sexual contact, blood and blood product exposure, and perinatal
exposure.
• Site of latency: CD4 T lymphocytes.
• Disease: Most disease in humans caused by HIV-1; infected cells include CD4 (helper)
T lymphocytes, monocytes, and some cells of the central nervous system;
asymptomatic infection, acute flulike disease, acquired immunodeficiency syndrome
(AIDS)–related complex, and AIDS-associated infections and malignancies.
• Detection: Serology, antigen detection, reverse transcriptase polymerase chain
reaction (RT-PCR).
• Those at risk of infection are homosexual or bisexual males, intravenous drug abusers,
sexual contacts of individuals infected with HIV, and infants of infected mothers.
2. Human T-lymphotropic viruses types 1 and 2 (HTLV-1, HTLV-2).
• Transmission: Known means of transmission are similar to those for HIV.
• Disease: T-cell leukemia and lymphoma, and tropical spastic paraparesis for HTLV-1;
no known disease associations for HTLV-2.
• Detection: Serology.
• Oncogenic: T-cell lymphoma (HTLV-1).

33. Rhabdoviridae
Rhabdovirus
Rabies virus
• Transmission:
• Bite of rabid animal most common; 20% of human rabies cases have no known
exposure to rabid animal.
• Disease:
• Rabies.
• Detection:
• Fluorescent antibody (FA) staining, polymerase chain reaction (PCR).
• CPE (Negri bodies).
• Prevention:
• Avoid contact with rabid animals; vaccinate domestic animals; post-exposure
prophylaxis with hyperimmune antirabies globulin and immunization with rabies
vaccine.

34. Togaviridae
Togaviruses
1. Rubella virus:
• Transmission:
Respiratory, transplacental.
• Disease:
• Rubella (mild), congenital rubella.
• Detection:
• Serology.
• Prevention:
• Rubella vaccine.
2. Arboviruses referred to as alphaviruses:
• Transmission:
• Arthropod vector, usually mosquito.
• Disease:
• Eastern, Western, and Venezuelan equine encephalitis.
• Detection:
• Serology and antibody detection in cerebrospinal fluid (CSF).

35. • First marker that appears in HBV: HBsAg.
• HCV confirmed by RIBA (Recombinant Immunoblot assay).
• HDV: Only HBsAg positive patients are tested for HDV, HDV-Ag is the first
marker, IgM anti-HDV appears next followed by low levels of IgG anti-HDV.

38. Alyazeed Hussein, BSc, SUST
This has been a presentation of Alyazeed Hussein
Thanks for your attention and kind patience
@elyazeed7
@Alyazeed7ussein