1. Parvoviridae Parvoviruses Human Parvovirus B19

2. ( Introduction ) Human parvovirus B19: Smallest DNA-containing virus, have a tropism for erythroid progenitor cell (actively dividing cells), and it cause variety of human diseases. Human parvovirus B19: Smallest DNA-containing virus, have a tropism for erythroid progenitor cell (actively dividing cells), and it cause variety of human diseases. Parvoviruses: Parvoviruses: Simplest DNA viruses. Simplest DNA viruses. Small coding capacity of their genome. Viral replication is dependent actively replicating host cells. Small coding capacity of their genome. Viral replication is dependent actively replicating host cells. Nomenclature: Nomenclature: Human Parvovirus B19. parvo mean small. Human Parvovirus B19. parvo mean small. B19, code number of human serum, virus was first discovered.

3. ( History and the discovery of the virus ) Discovered in 1975. assays of serum samples for hepatitis B surface antigen, by using counter-immunoelectrophoresis (CIEP). Discovered in 1975. assays of serum samples for hepatitis B surface antigen, by using counter-immunoelectrophoresis (CIEP). Sample number 19 in panel B gave “false-positive” result. Precipitin line was excised, examined by EM showed the presence of 23 nm particles resembling Parvoviruses. Sample number 19 in panel B gave “false-positive” result. Precipitin line was excised, examined by EM showed the presence of 23 nm particles resembling Parvoviruses. 1985: virus named Human Parvovirus B19. 1985: virus named Human Parvovirus B19.

4. ( Classification of Parvoviruses ) 1- Family: Parvoviridae. 1- Family: Parvoviridae. 2- Subfamilies: two 2- Subfamilies: two I. Parvovirinae. (vertebrate ). I. Parvovirinae. (vertebrate ). II. Densovirinae. (invertebrate). II. Densovirinae. (invertebrate). 3- Genera: 3- Genera: Parvovirinae comprise three genera, based on their ability to replicate: 1- Genus Parvovirus (autonomously). 2- Genus Dependovirus (helper virus). 3- Genus Erythrovirus (only in erythroid cells). Parvovirinae comprise three genera, based on their ability to replicate: 1- Genus Parvovirus (autonomously). 2- Genus Dependovirus (helper virus). 3- Genus Erythrovirus (only in erythroid cells). Human Parvovirus B19 replication occurs only in human erythrocyte precursors, is the sole member of the erythrovirus genus. Human Parvovirus B19 replication occurs only in human erythrocyte precursors, is the sole member of the erythrovirus genus.

5. ( Properties of the virus ) I. Physical properties: I. Physical properties: Virion : 1- Size and shape: Small (20-25 nm), icosahedral, non enveloped. Virion : 1- Size and shape: Small (20-25 nm), icosahedral, non enveloped. 2- Virus outer capsid proteins (VP1, VP2). 2- Virus outer capsid proteins (VP1, VP2). 3- Genome: ss DNA, size 5.5 kb in length. 3- Genome: ss DNA, size 5.5 kb in length. II. Biological properties: II. Biological properties: lack of envelope and the limited DNA content, B19 is extremely resistant to physical inactivation. lack of envelope and the limited DNA content, B19 is extremely resistant to physical inactivation. Virus is resistant to: 1- Heat: 56°C for 60 minutes. 2- pH: 3 – 9. 3- lipid solvents: such as ether and chloroform. Virus is resistant to: 1- Heat: 56°C for 60 minutes. 2- pH: 3 – 9. 3- lipid solvents: such as ether and chloroform. Virus inactivated by: 1- Formalin. 2- ß- propiolactone. Virus inactivated by: 1- Formalin. 2- ß- propiolactone. 3- Oxidizing agents 3- Oxidizing agents

6. ( Pathogenesis ) Source: Human (patients), Respiratory secretion, blood. Source: Human (patients), Respiratory secretion, blood. Mood of transmission: 1- Horizontally: Infection is spread by a respiratory route. 2- Parenteral: blood transfusion or infected blood products. 3- Vertically: trans placental transmission from mother to fetus. Mood of transmission: 1- Horizontally: Infection is spread by a respiratory route. 2- Parenteral: blood transfusion or infected blood products. 3- Vertically: trans placental transmission from mother to fetus. Route of entry: Respiratory tract. Directly into blood. Route of entry: Respiratory tract. Directly into blood. Spread: Blood, tropic for human erythroid cells in BM. ( Mitotically active cells for replication). Spread: Blood, tropic for human erythroid cells in BM. ( Mitotically active cells for replication). Target receptor (Cells, tissues): The cellular receptor for B19 is blood group P antigen (globosids). Target receptor (Cells, tissues): The cellular receptor for B19 is blood group P antigen (globosids). P antigen is expressed on: P antigen is expressed on: 1 - Mature erythrocytes. 1 - Mature erythrocytes. 2- Erythroid progenitors. 3- Megakaryocytes. 2- Erythroid progenitors. 3- Megakaryocytes. 4-Endothelial cells. 4-Endothelial cells. 5- Placenta, Fetal heart and liver. 5- Placenta, Fetal heart and liver. Tissue : site of viral replication 1- Adult: bone marrow. 2- Fetus: fetal liver. Tissue : site of viral replication 1- Adult: bone marrow. 2- Fetus: fetal liver.

7. Mechanism of tissue damage induced by the virus I. Direct effects: Viral replication in the erythroid cells cause cell death and interruption of RBC production. I. Direct effects: Viral replication in the erythroid cells cause cell death and interruption of RBC production. II. Indirect effects: antibodies to parvovirus result in formation of immune complex which deposit in tissue and cause damage. II. Indirect effects: antibodies to parvovirus result in formation of immune complex which deposit in tissue and cause damage.

8. CLINICAL MANIFESTATIONS Human Parvovirus B19 Diseases: Human Parvovirus B19 Diseases: 1- Immunocomptenet hosts: Children: Erythema infectiosum, EI (skin). Adults: Polyarthralgia arthraitis syndrome (Joints). 1- Immunocomptenet hosts: Children: Erythema infectiosum, EI (skin). Adults: Polyarthralgia arthraitis syndrome (Joints). 2- Immunocompromised patients: Pure red cell aplasia (PRCA) result in chronic anemia. 2- Immunocompromised patients: Pure red cell aplasia (PRCA) result in chronic anemia. 3- Haematological disorder: Transient aplastic crisis, TAC. 3- Haematological disorder: Transient aplastic crisis, TAC. 4- Intrauterine infection: Fetal infection, manifested by fetal anemia, hydrops fetalis and death. 4- Intrauterine infection: Fetal infection, manifested by fetal anemia, hydrops fetalis and death.

9. Erythema Infectiosum, Polyarthralgia arthritis syndrome Children: Erythema Infectiosum, (fifth disease) ( skin rash). Adults: Polyarthralgia arthritis syndrome (joints). almost certainly immune complex disorder. Children: Erythema Infectiosum, (fifth disease) ( skin rash). Adults: Polyarthralgia arthritis syndrome (joints). almost certainly immune complex disorder. Incubation period is 4-14 days. Incubation period is 4-14 days. Entry: respiratory tract. Entry: respiratory tract. Spread: one week, viremia is started and persist for about 5 days. Shedding is the pharynx and nasal secretion. Spread: one week, viremia is started and persist for about 5 days. Shedding is the pharynx and nasal secretion. Disease is biphasic illness with symptoms during viremic and immune complex mediated stage. Disease is biphasic illness with symptoms during viremic and immune complex mediated stage. 1- First phase ( viremic stage): occur at the end of the first week and associated clinically with: Flu-like illness (fever, coryzia, headache, myalgia). GIT symptoms: mild (nausea and diarrhea). 1- First phase ( viremic stage): occur at the end of the first week and associated clinically with: Flu-like illness (fever, coryzia, headache, myalgia). GIT symptoms: mild (nausea and diarrhea). 2- Second phase : ( immune complex deposition in tissue ): 2- Second phase : ( immune complex deposition in tissue ):. Children (EI): skin rash maculopapular, affect the face (facial rash ), limb, trunk, resolves in a week.. Children (EI): skin rash maculopapular, affect the face (facial rash ), limb, trunk, resolves in a week. Adults (Polyarthralgia arthritis syndrome): Clinically (joints): arthritis, symmetrical and peripheral, wrists, hands and knees. resolves in 3 weeks. some arthritis (non destructive) remain months or years. Adults (Polyarthralgia arthritis syndrome): Clinically (joints): arthritis, symmetrical and peripheral, wrists, hands and knees. resolves in 3 weeks. some arthritis (non destructive) remain months or years.

10. 2- Pure red cell aplasia (PRCA) B19 infection in patients with immunodeficiency diseases like: B19 infection in patients with immunodeficiency diseases like: 1- Congenital immunodeficiency. 2- Human immunodeficiency virus. 3- Acute lymphocytic leukemia 4- Organ transplants. 1- Congenital immunodeficiency. 2- Human immunodeficiency virus. 3- Acute lymphocytic leukemia 4- Organ transplants. Mechanism: Patients unable to eliminate B19 infection, because they cannot produce adequate levels of virus-specific antibodies. Result is persistent infection with destruction of erythroid precursor cells in the BM and chronic anemia. Mechanism: Patients unable to eliminate B19 infection, because they cannot produce adequate levels of virus-specific antibodies. Result is persistent infection with destruction of erythroid precursor cells in the BM and chronic anemia. Cured or controlled: by immunoglobulin therapy. Cured or controlled: by immunoglobulin therapy.

11. 3- Transient Aplastic Crisis (TAC) Patients with chronic hemolytic disease, result in TAC. Patients with chronic hemolytic disease, result in TAC. Chronic hematological disease include: 1- Chronic hemolytic anemia (sickle cell disease, thalassemias). 2- Idiopathic thrombocytopenic purpura. 3- BM transplantation. Chronic hematological disease include: 1- Chronic hemolytic anemia (sickle cell disease, thalassemias). 2- Idiopathic thrombocytopenic purpura. 3- BM transplantation. Mechanisms: The infection lowers the production of erythrocytes, causing reduction in the hemoglobin level of peripheral blood. Mechanisms: The infection lowers the production of erythrocytes, causing reduction in the hemoglobin level of peripheral blood. The temporal arrest of production of red blood cells becomes apparent only in patient with chronic hemolytic anemia because of the short life span of their erythrocytes. The temporal arrest of production of red blood cells becomes apparent only in patient with chronic hemolytic anemia because of the short life span of their erythrocytes. Clinically: anemia (pallor, weakness), may need blood transfusion. Clinically: anemia (pallor, weakness), may need blood transfusion.

12. 4- Fetal and Congenital Infection Maternal infections, serious risk to the fetus. Maternal infections, serious risk to the fetus. Infected fetus may severely affected because: 1- Red blood cell turnover is high. 2- Immune response is deficient, result in persistent viral infection. Infected fetus may severely affected because: 1- Red blood cell turnover is high. 2- Immune response is deficient, result in persistent viral infection. Clinically: Clinically: 1- Severe anemia, hydrops fetalis. 2- Fetal death and fetal loss: occur in less than 10% of primary maternal infections. commonly before 20 th week of pregnancy (first and second trimester). Third trimester effective fetal immune response to the virus account for decrease in fetal loss at this stage of pregnancy. 1- Severe anemia, hydrops fetalis. 2- Fetal death and fetal loss: occur in less than 10% of primary maternal infections. commonly before 20 th week of pregnancy (first and second trimester). Third trimester effective fetal immune response to the virus account for decrease in fetal loss at this stage of pregnancy. 3- No evidence that parvovirus B19 infection cause congenital physical abnormalities. 3- No evidence that parvovirus B19 infection cause congenital physical abnormalities.

13. Laboratory Diagnosis I. Detection of viral DNA : most sensitive test, Samples: respiratory secretions, serum, and tissue sample( B.M ). Techniques: I. Detection of viral DNA : most sensitive test, Samples: respiratory secretions, serum, and tissue sample( B.M ). Techniques: 1- Dot Blot hybridization of serum or tissue extract. 2- In-situ hybridization of fixed tissue. 1- Dot Blot hybridization of serum or tissue extract. 2- In-situ hybridization of fixed tissue. 3- PCR: amplification and detection of viral nucleic acid. 3- PCR: amplification and detection of viral nucleic acid. II. Serology for detection of serum antibodies: II. Serology for detection of serum antibodies: Types: Types: 1- B19-specific IgM ( indicate recent infection), detected for up to 3 months after the onset. 1- B19-specific IgM ( indicate recent infection), detected for up to 3 months after the onset. 2- B19 IgG antibodies ( past infection), lasts longer and detectable lifelong following infection. 2- B19 IgG antibodies ( past infection), lasts longer and detectable lifelong following infection. Diagnostic importance of serum antibodies: Diagnostic importance of serum antibodies: I. B19-specific IgM. II. Rising titer of B19 specific IgG. I. B19-specific IgM. II. Rising titer of B19 specific IgG. Techniques: Techniques: Enzyme-Linked immunosorbent assay (ELISA). Enzyme-Linked immunosorbent assay (ELISA).  III- Culture:  Failed to grow in conventional cell culture lines.  Replicate only in human erythroid progenitor cells culture.

14. Transmission: respiratory or through blood and blood products. Transmission: respiratory or through blood and blood products. Seasonal: commonly as outbreaks of erythema infectiosum in schools during winter and spring months. Seasonal: commonly as outbreaks of erythema infectiosum in schools during winter and spring months. Rate of infection: Common 60% of adults possess serum antibodies. Rate of infection: Common 60% of adults possess serum antibodies. Prevention: 1- Interruption of virus transmission (respiratory) so patients with TAC and PRCA, should be separated from high risk patients. Prevention: 1- Interruption of virus transmission (respiratory) so patients with TAC and PRCA, should be separated from high risk patients. 2-No vaccine for B19 is currently available. 2-No vaccine for B19 is currently available. EPIDEMIOLOGY

15. HUMAN PAPILLOMAVIRUS INFECTIONS (HPVs) Family: Papillomaviridae. Genus: Papillomavirus. Members: Human papillomaviruses (HPVs). HPV was named because of an association with small epithelial proliferations: 'Papilla' = nipple (Latin). 'Oma' = tumour (Greek). HPVs selectively infect the epithelium of the skin and mucous membranes. These infections may be asymptomatic, produce warts, or be associated with a variety of benign and malignant neoplasias. 100 HPV types occur.

16. Characteristics of the virus 1- Nonenveloped, icosahedral in shape. 1- Nonenveloped, icosahedral in shape. 2- Size: measure 50 to 55 nm in diameter. 2- Size: measure 50 to 55 nm in diameter. 3- Genome: ds DNA, circular genome, about 7.9 kbp. 3- Genome: ds DNA, circular genome, about 7.9 kbp. 4- Capsids: composed of 72 capsomeres, capsomers located at each of the 12 vertices, are pentavalent and the other 60 capsomers are hexavalent. 4- Capsids: composed of 72 capsomeres, capsomers located at each of the 12 vertices, are pentavalent and the other 60 capsomers are hexavalent. 5- Replicated in nucleus, stimulate cell DNA synthesis, and viral oncoproteins interact with cellular tumor suppressor proteins. 5- Replicated in nucleus, stimulate cell DNA synthesis, and viral oncoproteins interact with cellular tumor suppressor proteins. 6- Oncogenic potential: significant cause of human cancer especially cervical cancer. 6- Oncogenic potential: significant cause of human cancer especially cervical cancer.

17. PATHOGENESIS Source: skin lesion, new lesions are probably more infective than older. Source: skin lesion, new lesions are probably more infective than older. Transmission: Spread is via direct contact, genital area transmitted via sexual route. Transmission: Spread is via direct contact, genital area transmitted via sexual route. Target: HPV are highly tropic for epithelial cells of the skin and mucous membrane. All types of squamous epithelium can be infected by HPV. Target: HPV are highly tropic for epithelial cells of the skin and mucous membrane. All types of squamous epithelium can be infected by HPV. Replication of HPV: begins with the infection of basal cells. As cellular differentiation proceeds, HPV DNA replicates and is transcribed. Ultimately, virions are assembled in the nucleus and released when keratinocytes are shed. Replication of HPV: begins with the infection of basal cells. As cellular differentiation proceeds, HPV DNA replicates and is transcribed. Ultimately, virions are assembled in the nucleus and released when keratinocytes are shed. This process is associated with proliferation of all epidermal layers except the basal layer and produces hyperkeratosis. This process is associated with proliferation of all epidermal layers except the basal layer and produces hyperkeratosis. Histologically normal epithelium may contain HPV DNA, and residual DNA after treatment can be associated with recurrent disease. Histologically normal epithelium may contain HPV DNA, and residual DNA after treatment can be associated with recurrent disease.

18. CLINICAL MANIFESTATIONS Incubation period of HPV disease is usually 3 to 4 months, up to 2 years. Incubation period of HPV disease is usually 3 to 4 months, up to 2 years. These infections may be: These infections may be: 1- Asymptomatic. 1- Asymptomatic. 2- Produce warts. 2- Produce warts. 3- Associated with a variety of benign and malignant neoplasia. 3- Associated with a variety of benign and malignant neoplasia. The clinical manifestations of HPV infection depend on the location of the lesions and the type of virus. Warts in humans, including: Warts in humans, including: 1- Skin warts (Common warts ): benign, usually occur on the hands as flesh-colored to brown, often regress spontaneously. (HPV 2,4,27,57). 1- Skin warts (Common warts ): benign, usually occur on the hands as flesh-colored to brown, often regress spontaneously. (HPV 2,4,27,57). 2- Planter warts: painful. (HPV 1). 2- Planter warts: painful. (HPV 1). 3- Flat wart: common among children, face, neck, chest, and flexor surfaces of the forearms and legs. ( HPV 3,10, 28). 3- Flat wart: common among children, face, neck, chest, and flexor surfaces of the forearms and legs. ( HPV 3,10, 28). 4- Anogenital warts (genital condyloma): 4- Anogenital warts (genital condyloma): sexually transmitted genital lesions skin and mucosal surfaces of the external genitalia and perianal areas. caused by specific types of papillomavirus 6,11,40, 42-44,54, types HPV16 and HPV18, regularly become malignant if they persist for a sufficiently long time. sexually transmitted genital lesions skin and mucosal surfaces of the external genitalia and perianal areas. caused by specific types of papillomavirus 6,11,40, 42-44,54, types HPV16 and HPV18, regularly become malignant if they persist for a sufficiently long time. 5- Laryngeal papilloma type HPV6, HPV11., children. 5- Laryngeal papilloma type HPV6, HPV11., children.

19. Types of anogenital cancer and HPV types: I. Cervical cancer: I. Cervical cancer: Strong association: HPV16, 18, 31, 45 Moderate association: HPV 33, 35, 39, 51, 52, 56, 58, 59, 68 Weak or no association: HPV 6, 11, 26, 42, 43, 44, 53, 54, 55, 62 II. Vulvar cancer: HPV 16. II. Vulvar cancer: HPV 16. III. Penile cancer: HPV 16. III. Penile cancer: HPV 16.

20. DIAGNOSIS I. Clinical diagnosis: Most warts that are visible to the naked eye can be diagnosed clinically alone. I. Clinical diagnosis: Most warts that are visible to the naked eye can be diagnosed clinically alone. II. Laboratory diagnosis: II. Laboratory diagnosis: 1- The most sensitive and specific methods : 1- The most sensitive and specific methods : the polymerase chain reaction or the hybrid capture assay to detect HPV nucleic acids and to identify specific virus types. the polymerase chain reaction or the hybrid capture assay to detect HPV nucleic acids and to identify specific virus types. 2- Serologic techniques to diagnose HPV infection are in the early stages of development and are not yet widely available. 3- Culture: HPV cannot be efficiently propagated in cell culture:

21. Treatment Frequently used therapies include cryosurgery, application of caustic agents, surgical excision, and ablation with a laser. Frequently used therapies include cryosurgery, application of caustic agents, surgical excision, and ablation with a laser. Topical antimetabolites such as 5-fluorouracil also have been used. Both failure and recurrence have been well documented with all of these methods of treatment. Topical antimetabolites such as 5-fluorouracil also have been used. Both failure and recurrence have been well documented with all of these methods of treatment. Various interferon preparations have been employed with modest success. Various interferon preparations have been employed with modest success.

22. Prevention: HPV vaccine. HPV vaccine. I. Prophylactic vaccination. I. Prophylactic vaccination. II. Therapeutic vaccines: develop therapeutic vaccines to treat people infected with HPVs. II. Therapeutic vaccines: develop therapeutic vaccines to treat people infected with HPVs. HPV vaccine is an inactivated virus particles (not live) vaccine HPV vaccine is an inactivated virus particles (not live) vaccine which protects against 4 major types of HPV. which protects against 4 major types of HPV. These include: These include: 2types that cause about 70% of cervical cancer (HPV 16 and 18) and 2 types that cause about 90% of genital warts (HPV 6 and 11).. 2types that cause about 70% of cervical cancer (HPV 16 and 18) and 2 types that cause about 90% of genital warts (HPV 6 and 11).. HPV vaccine can prevent most genital warts and most cases of cervical cancer. Protection from HPV vaccine is expected to be long-lasting. Protection from HPV vaccine is expected to be long-lasting.