Repetitorium of selected human viruses HIV

Transcription

1 Repetitorium of selected human viruses HIV Chair and Department of Medical Microbiology Poznan University of Medical Sciences Chairman: prof. dr hab. Andrzej Szkaradkiewicz Wieniawskiego Street 3, Poznań

2 The most frequent viral infections spreading droplet inhalation and/or by contact Family: Orthomyxoviridae [(-)ssrna] enveloped viruses Human influenza viruses A, B and C (IAV, IBV and ICV) Note: IAV infects birds, mammals and humans which results in formation of a new virus subtypes, mainly due to exchange of individual genome segments (the so called antigenic jump). The new subtypes of the virus repfresent an etiological factor of new epidemic or pandemic of influenza. IBV is manifested exclusively in humans (within the type antigenic changes, the so called antigenic drift, cause seasonal epidemics of influenza) while ICV developes in humans and in igs. ICV used to induce mild pharyngitis, frequently with conjunctivitis. Diagnosis: examination of nasopharyngeal smears using rapid diagnostic tests and molecular diagnosis (detection of viral RNA). Recommended treatment: zanamivir, oseltamivir. Family: Herpesviridae (dsdna) enveloped viruses Note: herpesviruses ara capable of inducing primary and relapsing (usually productive infections, frequently associated with clinical signs/symptoms) and latent infections (persisting hidden infections ). Viruses of Herpes simplex (HSV-1, HSV-2) Diseases: herpetic stomatitis and pharyngitis, genital herpes, herpetic meningitis and encephalitis Varicella zoster virus (VZV) Diseases: varicella, herpes zoster cytomegalovirus (CMV) Diseases :cytomegaloviral mononucleosis, hepatitis, inborn infections - Epstein-Barr virus (EBV) Diseases:infectious mononucleosis, Burkitt s lymphoma, nasopharyngeal carcinoma, lymphoproliferative syndromes. Diagnosis in infections with HSV, VZV or CMV detection of viral DNA by PCR (mainly in diagnosis of cerebrospinal fluid). In infectious mononucleosis: serological diagnosis antibodies anti-vca EBV and anti-ea EBV (ELISA). Recommended treatment: acyclovir (ACV), walacyclovir (VCV), gancyclovir (GCV); in infectious mononucleosis application of the drugs is ineffective.

3 Neurotropic infection virus of rabies Family: Rhabdoviridae [(-)ssrna] enveloped viruses Virus of rabies (RABV) genus of Lyssavirus Induces the acute zoonotic infectious disease rabies, leading to death. Note: RABV is transmitted with saliva of the infected animal (most frequently cat or fox) through the transdermal route or transmucosal route (biting, contamination with saliva). RABV is a highly neurotropic virus, it spreads and replicates in nervous system. RABV is not present in blood. Foci of extranervous replication of RABV: cells of olfactory epithelium, cells of cornea, parotid glands and skin of the neck (particularly nuchal skin at the height of hairy skin). Rapid supravital diagnosis: - detection of RABV antygen using immunofluorescent method (DFA) in imprint preparations from cornea and in smears of saliva or in bioptates sampled from nuchal skin at the height of hairs ( gold standard in supravital laboratory diagnosis of rabies); - molecular diagnosis: detection of RABV RNA in saliva, cerebrospinal fluid and in sin biopsies from the neck. Note: no test is fully effective in diagnosis of rabies, therefore it is recommended to perform few tests in parallel. In diagnosis of rabies no serological ELiSA tests are performed. Causal treatment of rabies does not exist. Post-exposure prophylaxis is absolutely necessary; vaccination against rabies in justified cases involve a single administration of anti-rabv anti-viral serum in persons bitten or smeared with saliva of an animal suspected of infection.

4 Viruses of hepatitis: A, B, C and E Hepatitis virus A (HAV) genus: Hepatovirus, family: Picornaviridae [(+)ssrna] an unenveloped virus HAV is excreted with stools; it spreads by alimentary pathway; it is stable in acidic environment down to ph=3.0. Note: it induces frequently epidemic morbidity. HAV does not induce chronic diseases of the liver. Diagnosis: detection of serum IgM HAV-specific antibodies ( the gold standard ). No causal treatment is available. Hepatitic virus B (HBV) family of Hepadnaviridae [dsdna] an enveloped virus Note: HBV induces acute and chronic hepatitis; HBV represents a WHO-recognised risk factor of hepatocellular liver cancer - HCC (the virus 100-fold augments the risk of developing HCC). It spreads by extraintestinal manner (through violation of tissue integrity, e.g. by performance of procedures using contaminated medical equipment, by introduction of contaminated blood, use of virus-contaminated needles for tatooing, acupuncture). Also, the risk is high of infections spreading through sexual contacts (in USA infection with HBV was recognised to represent venereal infection); also a foetus may become infected from his mother Diagnosis: detection using the ELISA test of viral antigens HBsAg and HBeAg and of serous antibodies specific for HBcAg, HBsAg and HBeAg ( IgM antibodies specific for y-hbcag represent the most reliable marker of acute type B hepatitis). Recommended treatment: nucleoside or nucleotide inhibitors of HBV polymerase. Hepatitic virus C (HCV) genus: Hepacivirus, family: Flaviviridae [(+)ssrna] an enveloped virus Note: HCV inducs acute and chronic hepatitis (clinically frequently asymptomatic); HCV represents a WHO-recognised risk factor of developing hepatocellular cancer - HCC (the virus augments 20-fold the risk of developing HCC). It spreads similar to HBV by extraintestinal manner and by sexual contacts, probably also by maternal transmission to the foetus. Diagnosis: HCV is detected by serological techniques (testing of serum for presence of anti-hcv antibodies using ELISA technique and in the molecular manner- detection of RNA-HCV (RNA-HCV represents the first marker of HCV infection). Recommended treatment: selective inhibitors of HCV protease + inhibitors of HCV replication complex. Wirus E (HEV) - genus: Hepevirus, family: Hepeviridae [(+)ssrna] an unenveloped virus Note: HEV induces acute and, only in immunosuppressed patients, chronic hepatitis. It spreads by alimentary pathway, also associated with consumption of infected, insufficiently boiled food (pork, hunter wild animals). Diagnosis: detection of serum IgM, HEV-specific antibodies using ELISA ( gold standard ). No causal treatment is available.

5 Human immunodeficiency virus (HIV) HIV genus: Lentivirus, Family: Retroviridae [(+)ssrna] an enveloped virus (gp41 + gp120) It induces the syndrome of acquired immune deficiency (AIDS) leading to death of the patient. It spreads pandemicaly in the world. Note: the virus represents the WHO-recognised risk factor of certain neoplastic diseases: Kaposi sarcoma and non-hodgkin lymphomas ; the virus augments 60-fold the risk of NHL development. Pathways of infection: - sexual (most frequently due to risky heterosexual contacts; infection with HIV may follow even a single relationship - with carrier of the virus -extraintestinal one (due to transfusion of HIV-positive blood, blood derivatives or use of contaminated needles, syringes) - mother to foetus infection. Diagnosis: the principal in routine diagnosis of HIV infection are serological tests: - detection in serum HIV antygen, i.e. of medullary p24 antigen by ELISA technique Note: HIV p24 Ag represents the first marker of HIV infection, detectable already after around 2 weeks after infection and detectable, on the average till 12 weeks; - detection in serum of anti-hiv antibodies (anti-gp160 or anti-gp120) by ELISA technique Note: serum anti-hiv antibodies are detectable beginning from 6th week after infection to the end of life. Nevertheless, in order to exclude false positive results it is necessary to use additional test: the Western blot test conducted in selected HIV diagnostic laboratories. Recommended treatment: combined anti-retroviral therapy (ART) based on combination of 3 drugs: An inhibitor of reverse transcriptase, inhibitor of integrase and inhibitor of protease. The treatment aims at reducingthe number of HIV RNA copies in serum to the threshold value of detectability (1-50 copies per ml).