Effects or Functions of Specialized Cells

Although they do not immediately kill cells, infections with noncytocidal viruses often interfere with the specialized functions of differentiated cells. For example, lymphocytic choriomeningitis (LCM) virus replicating in somatotropic cells of the pituitary gland of the persistently infected mouse lowers the production of the mRNA for growth hormone in the infected cells, thus impeding the growth and development of the animal. Similarly, LCM virus replicating in 3 cells of the islets ol...

Components of the Immune System

The immune system comprtses several kinds ot lymphocytes as well as cells of the monocyte macrophage lineage, dendritic cells, and NK cells. Lymphocytes, with their specific surface receptors, are the key to immunologic specificity Any given 1 or B lymphocyte possesses receptors with specificity for a particular epitope. When T or B lymphocytes bind antigen they respond by dividing to form an expanded clone of cells (clonal expansion) The B lymphocytes differentiate into plasma cells, which...

Vital Genitourinary Infections

Two major viral sexually transmitted diseases (STD), genital herpes and genital warts, dramatically increased in frequency during the sexual revolution of the 1960s and 1970s. The painful itchy lesions of genital herpes (Fig 20-6) and the accompanying local and systemic symptoms were described in Chapter 20. Dozens of recurrences, mainly attributable to HSV-2 but increasingly to HSV-1 also, may dominate the life of the hapless carrier. Genital warts, caused most commonly by the human...

Hepadnaviridae and Deltavirus

Properties of Hepadnaviridae 359 Clinical Features of Hepatitis B 362 In 1963 Blumberg, a geneticist investigating hereditary factors in the sera of isolated racial groups, discovered an antigen in the serum of an Australian aborigine that reacted with sera from multiply transfused American hemophiliacs. In due course the antigen was demonstrated to be present on the surface of particles with three different morphologic forms (Fig. 22-1) and to be associated with the disease serum hepatitis,...

Types of Mutations

Mutations can be classified either according to the kind of change in the nucleic acid or on the basis of their phenotypic expression. Classification of Mutants by Changes in the Genome The most common mutations are single nucleotide substitutions (point mutations) or deletions and insertions, which may involve a single nucleotide or more commonly small blocks of nucleotides. Each point mutation has a characteristic frequency of reversion which can be accurately measured. The phenotypic...

Immune Response Genes

Immunologic responses are determined and controlled by a large number of different genes usually located in clusters, but on different chromosomes. A variety of inherited defects in these genes is recognized. These range from the absence of a single immunoglobulin class such as IgA, the commonest primary defect in humans, to agammaglobulinemia, where the number of functional B cells is greatly reduced or absent Even more serious, for many viral diseases, are congenital deficiencies in...

Viral Infections in Immunocompromised Patients

Whereas some viral infections induce immunosuppression, certain noninfectious diseases, such as malignancy, or procedures used for therapy, including chemotherapy, radiation, and organ transplantalion, may adversely affect the immune system and thus allow enhanced viral replication. The immunocompromised state may be due to genetic defects in the immune system, such as congenital agammaglobulinemia. Most commonly, however, immune dysfunction is due to some other disease, especially tumors that...

Types of Epidemiologic Investigations

Cross-Sectional, Case-Control, and Cohort Studies Epidemiologic methods used to determine the incidence and prevalence of infectious diseases, the relationships between cause and effect, and the evaluation of risk factors include the cross-sectional study, the case-control study, and the cohort study. A cross-sectional study can be carried out relatively quickly and provides data on the prevalence of particular diseases in the population. A case-control study, the most common kind of...

Info

Much higher titer in plasma, hencc higher probability of transmission by transfusion of (unscreened) blood or blood products and needle sharing among injecting drug users '' Congenital infection of fetus during first 16 weeks of pregnancy Much higher titer in plasma, hencc higher probability of transmission by transfusion of (unscreened) blood or blood products and needle sharing among injecting drug users '' Congenital infection of fetus during first 16 weeks of pregnancy commonly integrated...

Clinical Features

Crimean-Congo hemorrhagic fever commences abruptly with fever, headache, and severe back and abdominal pain, and progresses to extensive hemorrhages from almost any site, with melena, hematemesis, hematuria, and a hemorrhagic skin rash (Fig. 33-4). Leukopenia, thrombocytopenia, proteinuria, and hepatitis are key findings. Blood loss from internal bleeding leads to shock, pulmonary edema, and death. Case-fatality rates range from 5 to 50 , depending on the availability of modern medical care....

Immunization against Viral Diseases

Inactivated Virus and Virus Subunit Vaccines 223 Methods for Enhancing Immunogenicity 226 Comparison of Different Classes of Vaccines 227 Immunization is the most generally applicable way of preventing infectious disease. The control of so many important viral diseases by immunization is arguably the outstanding medical achievement of the twentieth century, recognized by the award of several Nobel prizes. Traditionally, there have been two major strategies for the production of viral vaccines,...

P

Including herpes simplex virus infection of burns, eczema herpeticum, elc. Skin above waist, 1 > 2, below waist, 2 > 1, arms, either 1 or 2 Ollen fatal Including herpes simplex virus infection of burns, eczema herpeticum, elc. Skin above waist, 1 > 2, below waist, 2 > 1, arms, either 1 or 2 Ollen fatal retains HSV DNA in the trigeminal ganglion for life and has at least a 50 chance of suffering recurrent attacks of herpes labialis (otherwise known as herpes facialis, herpes simplex,...

S

Laboratory, 216-217, 489, 503 of vaccines, 229-230 Sandfly fever, 515 Sanitation, 257-258 Satellite virus, 27, 373 Scabby mouth, sec Orf Scrapie, 160, 162-163 Season, effect on virus infection, 246-248 Sentinel study, 241 Seoul virus, 511, 519 Seroepidemiology, 237 Serum, antibody assay, 210-216 Sexually transmitted diseases (STD), 91, 580 hepatitis B virus, 369 herpesvirus, 325-326 human immunodeficiency viruses, 555-557 human T-cell leukemia viruses, 538 papillomavirus, 302 molluscum...

Rna Viruses

Fig. 2-1 Shapes and sizes of viruses of families that include human pathogens. The virions are drawn to scale, but artistic license has been used in representing then structure In some, the cross-sectional structure of capsid and envelope is shown, with a representation of the genome, with the very small virions, only size and symmetry are depicted Genus. Erylhroi'irus (human parvovirus B19) Genus Deprmlmnrns (adeno-associated viruses) Parvoviruses (parvus, small) are about 20 nm in diameter,...

Clinical Features of Hepatitis B

Most HBV infections are subclinical, particularly during childhood, but about one-third of adult infections are icteric. The course of acute viral hepatitis is conventionally divided into three phases (1) preicteric, (2) icteric, and (3) convalescent. Following a long incubation period of 6-26 weeks in the case of hepatitis B, the preicteric (prodromal) phase commences with malaise, lethargy, anorexia, and commonly nausea, vomiting, and pain in the right upper abdominal quandrant. A minority of...

Herpesviridae

Properties of Herpesviridae 318 All herpesviruses have the capacity to persist in their hosts indefinitely in the form of an episome in the nucleus of the cells that harbor them. Virtually every vertebrate species that has been carefully searched is found to support at least one host-specific herpesvirus which has evolved with that host species for millennia. Sometimes, as in humans, host-specific herpesviruses of different subfamilies occupy distinct ecologic niches, noncompetitively, in...

Viral Diseases of the

Conjunctivitis Adenoviruses 3, 4, 7, others Corneal ulceration Ophthalmic zoster Pandemics radiculomyelitis Sandfly fever Dengue Measles Rubella Keratoconjunctivitis Adenoviruses 8, 37, others Keratoconjunctivitis Adenoviruses 8, 37, others ertteroviral infections, and it is an important component of the dengue-like syndromes caused by many arboviruses, such as phlebotomus (sandfly) fever. Infections with adenoviruses, notably types 3, 4, and 7 in children, present as a bilateral follicular...

Poxviridae

Child Moiiuscum Contagiosum Diseases

Human Infections with Orthopoxviruses 353 Human Infections with Parapoxviruses 356 The family Poxviridae is divided into two subfamilies, Clmrdopoxviriniie poxviruses of vertebrates and Eiitoniopoxvirinae poxviruses of insects only the former are of importance in medicine. The subfamily Chordopoxvirinae contains eight genera, distinguished on the basis of genetic, antigenic, and morphologic differences. Several poxviruses causes diseases in humans smallpox now extinct , vaccinia including a...

Viral Pancreatitis and Diabetes

Several viruses occasionally infect the pancreas in humans. Mumps, for example, can be complicated by severe pancreatitis, and coxsackie B viruses or various other enteroviruses have been incriminated also. Of greater research interest is the question of whether viruses may trigger juvenile diabetes mellitus of the insulin-dependent type IDDM . Children born with the congenital rubella syndrome quite often develop IDDM before the age of 20. Mumps infections often affect the p cells of the...

Parainfluenza Viruses

Parainfluenza viruses are common human respiratory pathogens, in the main they produce relatively harmless upper respiratory tract infections URTI , but they are also the commonest cause of a more serious condition in young children known as croup and occasionally cause pneumonia. Human parainfluenza virus types 1 and 3 belong to the genus Paramyxovirus, whereas types 2, 4a, and 4b are now classified with mumps virus in the genus Rubulavirus. Primary infection, typically in a young child,...

Other Enteroviruses

Most enteroviruses are presumed to enter the body via ingestion and to grow well in both the throat and the intestinal tract, but they are shed in the feces for much longer than in respiratory secretions. Dissemination via the bloodstream is doubtless the route of spread to the wide range of target organs susceptible to attack. Little is known of the factors that determine the tropism of different enteroviruses, for example, the predilection of coxsackie B viruses for muscle or of enterovirus...

Genetic Changes in Influenza A Virus

Human influenza virus was first isolated in 1933 Since that time human influenza viruses have been recovered from all parts of the world, and their antigenic properties have been studied in considerable detail, thus providing an opportunity for observing continuing evolutionary changes. Influenza A virus occurs in humans, swine, horses, birds, and aquatic mammals. Subtypes are classified according to the two envelope antigens, the hemagglutinin HA, or H and neuraminidase NA, or N All of the...

Viral Damage to Tissues and Organs

Diarrhea Rotavirus

The mechanisms by which viruses damage cells were discussed at the cellular and subcellular levels in Chapter 5. Here we apply these concepts at the level of tissues and organs. The severity of disease In humans is not necessarily correlated with the degree of cytopathology produced by the virus in vitro. Many viruses that are cytocidal in cultured cells generally do not produce clinical disease for example, enteroviruses, which cause severe cytopathic effects CPE in cultured human cells,...

Papillomaviruses

Host species-specific papillomaviruses have been found in many animals and birds. Most cause benign papillomas in the skin or mucous membranes. There are numerous human papillomaviruses HPV , most displaying a predilection for a particular site in the body. Some have oncogenic potential. Fig. 18-1 Pajtovaviridac A flapilbmamrtii, B Pnltfiminvirus C Polt ontavmis, empty virions Bar, 100 nm. Courtesy Dr t A FolfeH Fig. 18-1 Pajtovaviridac A flapilbmamrtii, B Pnltfiminvirus C Polt ontavmis, empty...

Mechanisms of Survival of Viruses in Nature

Perpetuation of a virus in nature depends on the maintenance of serial infections, that is, a chain of transmission the occurrence of disease is neither required nor necessarily advantageous. Indeed, although clinical cases may be somewhat more productive sources of infectious virus than inapparent infections, the latter are generally more numerous and do not restrict the movement of infectious individuals, and thus provide a major mechanism of viral dissemination. As our knowledge of the...

Hepatitis E

The story of the original discovery of hepatitis E virus HEV in Soviet Central Asia is worthy of Scheherazade. An intrepid Soviet virologist, Balayan, investigating an outbreak of hepatitis in Tashkent, volunteered himself to drink a pooled filtrate of stools from the patients sure enough he developed hepatitis. After recovering a novel 32 nm virus from his own feces, he inoculated a filtrate of that material into monkeys, which in turn developed biochemical evidence of hepatitis and excreted...

Viral Skin Rashes

Types Viral Rashes

Many viruses involve the skin in one way or another Table 36-4 Some, such as papillomaviruses, poxviruses, and recurrent herpes simplex, produce relatively localized crops of lesions and few if any systemic symptoms. Others, such as those causing the childhood exanthemata, produce a generalized rash as part of a wider clinical syndrome that follows a systemic infection. These rashes vary greatly in their anatomic distribution and in the morphology of the individual lesions. They are classified...

Transcription

Dsdna Papovavirus

Having outlined the several contrasting strategies of expression of the viral genome, we are now in a position to describe in more detail the processes of transcription, translation, and replication of viral nucleic acid, beginning with transcription. The viral RNA of most plus sense ssRNA viruses binds directly to ribosomes and is translated in full or in part without the need for any prior transcriptional step. For all other classes of viral genomes, mRNA must be transcribed in order to begin...

Ict

Lairogenic infection, 242 cytomegalovirus, 334, 336-337 filoviruses, 487 hepatitis B virus, 369-370 hepatitis C virus, 448-449 human immunodeficiency viruses, 538, 555, 557 subacute spongiform encephalopathies, 160-161 IgA, 125-126, 127-128, 134, 169, 227-228 IgE, 125-126, 127-128, 141 IgG, 125-126, 127-128, 130, 134, 227 IgM, 125-126, 127-128, 130 assays, for diagnosis, 214-216 Immune complex disease, 157, 158, 166 hepatitis B, 157 lymphocytic choriomeningitis, 142 Immune cytolysis, 130-131...

Viral Diseases

Rational Use of the Laboratory 191 Collection, Packaging, And Transport of Specimens 193 Direct Identification of Virus, Vira Antigen, or Viral Genome 195 Measurement of Serum Antibodies 210 Why bother to establish a definitive laboratory diagnosis ol a viral infection when few effective chemotherapeutic agents are available and many viral diseases are clinically obvious or trivial This is a valid question. The majority of viral infections can be handled without recourse to the laboratory....

Respiratory Syncytial Virus

Oxygen Tent For Infant 1960s

Respiratory syncytial virus RSV is the most important respiratory pathogen of childhood, being responsible for about half of all cases of bronchiolitis and a quarter of all cases of pneumonia during I he first few months of life. The virus multiplies in the mucous membranes of the nose and throat in the very young and very old it may involve the trachea, bronchi, bronchioles, and alveoli. The incubation period is 4-5 days. Fatal cases usually show extensive bronchiolitis and pneumonitis with...

Hhv6

Types 1 and 2 Varicella virus Adenovmdae All adenoviruses Miiwainntlcie BK, JC polyomaviruses Recurrent excretion in saliva, genital Rrtioviiulnc Human immunodeficiency viruses Ht'i gt aitrm gt irnfae Hepatitis B virus Aiemipirulm' All arenaviruses Togiwirittac Rubella virus secietions, for years Recurs as zoster many years later intermittent excretion from throat and or feces Excreted in urine Persistent viremia, may occur in semen, saliva In rodents, intermittent shedding in urine Persistent...

Principles of Animal Virology

Chapter 1 Structure and Composition of Viruses Viral Morphology 4 Chemical Composition of Virions 10 Preservation of Viral Infectivity 14 Further Reading 15 Chapter 2 Classification and Nomenclature of Viruses Criteria for Viral Classification 16 Nomenclature 17 Families of DNA Viruses 17 Families of RNA Viruses 22 Other Viruses 27 Groupings Based on Epidemiologic Pathogenic Criteria Further Reading 29 The Viral Replication Cycle 31 Attachment 33 Uptake Penetration 35 Uncoating 36 Strategies of...