Fetal response to viral infection: interferon production in sheep.

When virus was inoculated intravenously during the third trimester, the gestating ewe produced only low amounts of serum interferon, whereas the fetal lamb had the capacity to produce extremely high amounts. There was no evidence of transplacental transfer of interferon between mother and fetus in either direction.

Optimal treatment of herpes simplex virus encephalitis in mice with oral acyclovir.

The effect of oral or intraperitoneal administration of acyclovir was evaluated in four experimental models of herpes simplex virus (HSV) encephalitis in mice. Mice were inoculated with HSV-1 or HSV-2 intracerebrally or with HSV-2 intranasally, intraperitoneally, or intravaginally. With all four routes of inoculation, oral acyclovir therapy significantly reduced mortality when started as late as 72 to 96 hours after viral challenge. Intraperitoneal acyclovir was not effective in protecting mice inoculated intravaginally, but was effective if given 24 to 48 hours after intracerebral or intranasal challenge and as late as 96 hours after intraperitoneal infection. Oral acyclovir was more active than intraperitoneal treatment in all four model infections. Levels of acyclovir inhibitory for HSV in cell culture were maintained in plasma and brain tissue throughout oral treatment but lasted only three to six hours after each intraperitoneal treatment. These results suggest that acyclovir may be useful in treating serious HSV infections in humans.

Acyclovir treatment of disseminated herpes simplex virus type 2 infection in weanling mice: alteration of mortality and pathogenesis.

Intranasal inoculation of weanling mice with herpes simplex virus type 2 (HSV-2) provides an experimental infection that closely resembles disseminated and central nervous system HSV infections of human neonates. Intraperitoneal treatment with acyclovir (ACV) successfully reduced mortality even when therapy was begun as late as 2 days and oral therapy as late as 4 days after viral challenge. Treatment with ACV beginning on day 1 completely inhibited HSV-2 replication in lung, spleen, kidney, olfactory lobe, and cerebrum and decreased viral titers in the pons by 2-3 logs. Comparison of these data with our previous experiments using adenine arabinoside and adenine arabinoside 5' monophosphate indicates that ACV is more effective in the murine model of neonatal disease and suggests that ACV may also be more effective in treating the disease in humans.

Acyclovir treatment of experimental genital herpes simplex virus infections. I. Topical therapy of type 2 and type 1 infections of mice.

Intravaginal inoculation of mice with herpes simplex virus (HSV) provides a model infection of genital herpes to determine the effectiveness of potential antiviral agents. topical (intravaginal) treatment with 1% or 5% acyclovir (ACV) in an ointment of gel vehicle initiated 3, 6 or 24 h after inoculation with HSV type 2, significantly inhibited viral replication in the genital tract and usually reduced final mortality. Treatment with 5% ACV initiated 48 or 72 h after infection also reduced vaginal virus titers but did not alter final mortality. When mice were inoculated with HSV type 1 treatment with 5% ACV significantly reduced viral replication in the genital tract when begun as late as 72 h. In HSV-2 infected mice, treatment initiated 3 h but not 24 h after infection prevented the establishment of latent infection in sacral ganglie. These results suggest that topical ACV may be effective antiviral agent for primary genital herpes in humans.

Anti-herpesvirus activity of adenine arabinoside analogues in tissue culture and a genital infection of mice and guinea pigs.

Four analogues of adenine arabinoside (ara-A) were compared for activity against herpes simplex virus (HSV) in tissue culture and in a genital infection of mice and guinea pigs. These analogues, 5'-monophosphate (ara-AMP), 5'-valerate ester (ara-AV), 2'3'-diacetate ester (ara-ADA), and 2',3',5'- triacetate ester (ara-ATA) have greater water and lipid solubility and resistance to deamination than ara-A. In mouse embryo fibroblast cells, similar viral inhibitory levels were noted with ara-A, AMP, and ara-Av, while ara-ADA and ara-ATA were 6-10 time less active. In mice infected intravaginally with HSV type 2 (HSV-2), intravaginal treatment with 10% concentrations of each of the compounds beginning 3 h after viral challenge, had no effect on infection rates, titers of virus in vaginal secretions, mortality rates or the mean day of death as compared with placebo-treated controls. In the HSV-2 genital infection of guinea pigs, treatment with 10% vaginal creams or placebo vehicle was initiated 6 or 24 h after viral inoculation. In animals treated at 6 h with ara-A, ara-AMP and ara-AV, there was complete inhibition of viral replication in the vaginal tract and development of external genital lesions. When treatment with these three drugs was delayed 24 h after infection, there was no effect on vaginal virus titers, but lesions severity was reduced by ara-A or ara-AMP therapy. Ara-ATA was ineffective whether begun at 6 or 24 h. The greater solubility in water and lipid as well as the resistance to deamination of ara-AMP and ara-AV did not appear to enhance their antiviral activity over that of ara-A. Additionally, ara-ADA and ara-ATA exhibited less activity both in tissue culture and in the experimental genital infections.

A comparison of phosphonoacetic acid and phosphonoformic acid activity in genital herpes simplex virus type 1 and type 2 infections of mice.

The activity of phosphonoacetic acid (PAA) and phosphonoformic acid (PFA) against four strains of herpes simplex virus type 1 (HSV-1) and four strains of HSV-2 were compared in tissue culture and in a murine model of genital herpes. In mouse embryo fibroblast cells, both drugs were three-fold more active against the HSV-1 strains than against the HSV-2 strains. In contrast, in the animal model infections, PAA appeared to be more active against the HSV-2 strains, while PFA was equally effective against both HSV types. In mice infected intravaginally with HSV-2 and treated with intravaginal 5% PAA, none of the treated mice became infected, replication of virus in the genital tract was completely inhibited, none of the infected mice died from encephalitis, and latent infection in lumbosacral ganglia of surviving animals was completely prevented. In HSV-1 genital infection treated with PAA, 20-60% of mice became infected, replication of virus in the genital tract was strikingly reduced, none of the infected mice died, and latent infection was completely prevented. In both HSV-2 and HSV-1 genital infections, 20-70% of animals treated with 8% PFA became infected, growth of virus in the genital tract was reduced significantly but not completely suppressed, mortality was variably altered, and there was a trend towards reduction in the frequently of latent infection. These results indicate that HSV-1 strains are more sensitive to PAA and PFA in tissue culture, but the HSV-2 strains are generally more amenable to therapy in the murine model of genital herpes. Although PAA appeared to be more active that PFA in the genital infection, both drugs significantly altered the course of the infection. Since dermal toxicity associated with PAA precludes its use in humans and since PFA is already undergoing trials in patients with recurrent herpes labialis, the current results suggest that topical PFA deserved further evaluation in the treatment of mucocutaneous HSV infections, including genital herpes.

More rapid isolation of herpes simplex virus in a continuous line of mink lung cells than in Vero or human fibroblast cells.

Herpes simplex virus (HSV) was isolated from clinical specimens more rapidly in mink lung (ML) cells, a continuous cell line available from a commercial supplier, than in Vero cells or human fibroblast (HF) cells. Stock strains of HSV type 1 (HSV-1) and HSV-2 titered higher in ML cells than in Vero or HF cells. ML cells were equivalent to rabbit kidney (RK) cells in the isolation of HSV in clinical specimens, but titers of stock HSV strains were lower. ML cells could be employed to type strains of HSV-1 and HSV-2, using the technique of differential susceptibility to bromovinyldeoxyuridine (BVDU). ML cells, therefore, are a convenient and useful cell line for the isolation and typing of HSV in diagnostic virology laboratories.

Insertion of a small central venous catheter in neonates and young infants.

Total parenteral nutrition (TPN) administered through a central venous catheter in low-birthweight neonates and infants has been complicated by mechanical catheter malfunctions and catheter-associated infections. A retrospective survey of catheter complications 66 infants with 90 pediatric Broviac (1.3 mm o.d.) and large-diameter (French size 3, 4, and 5) Silastic catheters revealed 17 mechanical malfunctions (27%) and 16 cases (26%) of catheter infections. The current study presents our experience using 58 small-diameter (0.635 mm o.d.) Silastic catheters for TPN in 53 neonates and infants. There were 13 episodes (22%) of mechanical problems such as accidental dislodgement, occlusion of the catheter, and perforation of the tubing. Only four cases (7%) of catheter-associated sepsis occurred, a significant reduction (p = 0.008) in this serious problem compared to the previous large catheter study. We have compared clinical features of both large- and small-diameter catheters and suggest specific guidelines for their use. The small-diameter Silastic catheter is safe, easily inserted, and effective in the critically ill, low-birthweight neonate and in young infants weighing less than 6 kg. The pediatric Broviac catheter is recommended for administration of long-term or home TPN to infants and children greater than 6 kg. These catheters are useful for multiple purposes such as blood drawing, chemotherapy, and nutritional support while the small catheter is not as versatile.

Herpes simplex virus infection of the fetus and newborn.

Although infrequent, untreated neonatal herpes results in death in half the cases and neurologic sequelae in three quarters of the survivors. Neonatal infection is usually acquired from maternal genital herpes, which is asymptomatic or unrecognized in 60% to 80% of women. The greatest risk of neonatal infection occurs when the mother has primary genital herpes involving the cervix at delivery, and the infant is premature and delivered with instrumentation (eg, scalp electrodes). More than 80% of neonates with herpes will have typical herpetic lesions of the skin, eye, or mouth, and most of the remainder will have either encephalitis or a sepsis syndrome with pneumonitis and hepatitis and negative bacterial cultures. Because herpes can mimic other neonatal infections, laboratory diagnosis is important, using cultures of the virus from lesions, peripheral blood white cells, or CSF. Treatment with intravenous acyclovir does reduce mortality and neurologic sequelae, but outcome is still guarded in babies with disseminated disease or encephalitis. Prevention focuses on caesarean section in women with active lesions at the time of impending delivery and avoidance of postnatal exposure. Further studies are needed to determine whether maternal screening (eg, HSV-2 type specific antibodies and vaginal cultures in selected women at delivery) will be cost effective in preventing neonatal herpes.

Infectious mononucleosis and Epstein-Barr virus. 1. Epidemiology, pathogenesis, immune response.

The evidence linking Epstein-Barr virus causally with infectious mononucleosis is compelling. The disease occurs only in persons who lack antibody to this virus, and serologic findings during the acute illness provide almost certain evidence for its etiologic association. Additional evidence is derived from transformation studies using lymphocytes from persons infected with Epstein-Barr virus. Epidemiologic studies have related the need for close contact with salivary secretions to the low communicability of infectious mononucleosis. The clinically relevant antibodies which develop during the disease, other than heterophile antibody, are those against the viral capsid antigen. Part 2 of this article considers the clinical picture, diagnosis, and management and begins on page 95.

Infectious mononucleosis and Epstein-Barr virus. 2. Clinical picture, diagnosis, management.

The diagnosis of infectious mononucleosis is confirmed by hematologic, biochemical, and serologic data. An absolute increase in peripheral mononuclear cells to at least 4,500/cu mm is an essential feature. The serologic hallmark of the disease is the presence of heterophile antibody. The age of the patient may affect the clinical presentation and laboratory findings. Therapy is largely supportive, with steroids being used only in the presence of certain severe complications.

Is it bacterial or viral? Laboratory differentiation.

To differentiate viral, chlamydial, and mycoplasmal infections from bacterial disease in office and in emergency room practice, a combination of epidemiologic and clinical features usually will suggest one or a few microorganisms. Following that, laboratory diagnosis can be more targeted. Definition of the specific etiology will enable the proper management choice of antibiotics, antivirals, or symptomatic therapy.

Proper use of the clinical microbiology laboratory.

The interaction between clinicians and microbiology laboratory staff has to be one of mutual benefit. The more the laboratory personnel know about your patients, the more meaningful and thorough will be the results. Communication is the key to success. Visit the microbiology laboratory and get to know the staff. The clinician also needs to be familiar with and use the most commonly used diagnostic tests for individual bacterial pathogens appropriately.

Outbreak of meningitis in a newborn intensive care unit caused by a single Escherichia coli K1 serotype.

Three cases of meningitis that occurred during a nine-day period in a newborn intensive care unit were caused by a single E. coli serotype 07:K1:H-. A single organism outbreak was suspected when the three spinal fluid isolates all possessed the same two unusual bacteriologic and biochemical characteristics: nonmotile and ornithine negative. Culture surveillance identified eight infants colonized with the same strain of E. coli; three of these infants are described. Clusters of cases of E. coli meningitis in newborn intensive care units should be evaluated and managed as potential outbreaks.

Synergistic infection with murine cytomegalovirus and Pseudomonas aeruginosa in mice.

A previous report from this laboratory demonstrated that mice infected intraperitoneally with a 0--20% lethal inoculum of murine cytomegalovirus (CMV) exhibited markedly enhanced mortality rates (90%--100%) within 48 hr after an intravenous injection of a 0--20% lethal inoculum of Pseudomonas aeruginosa. The current study demonstrated that mice infected with murine CMV alone had high titers of virus in multiple organs over a 20-day period, whereas mice injected with P. aeruginosa alone had a self-limited infection confined to the kidney. In the combined murine CMV-P. aeruginosa infection, titers of virus in tissues were changed very little. In contrast, P. aeruginosa was recovered in high concentrations from multiple organs, a finding which demonstrated a progressive systemic infection closely resembling that produced by a 100% lethal inoculum of P. aeruginosa alone in normal mice. An increased mortality rate due to P. aeruginosa in murine CMV-infected mice was dependent on inoculation of live bacteria and could not be explained by enhanced susceptibility to endotoxin. These results indicate that murine CMF markedly enhanced the suceptibility of mice to infection with P. aeruginosa and suggest that the virus altered mechanisms of host resistance important in recovery from bacterial infections.

Activity of human recombinant and lymphoblastoid interferons in human and heterologous cell lines.

Three human alpha interferon (HuIFN-alpha) preparations currently being used in clinical trials, rIFN-alpha A, rIFN-alpha 2, and lymphoblastoid IFN (LYM-IFN) had appreciable activity against encephalomyocarditis and vesicular stomatitis viruses (VSV) in guinea pig transformed and guinea pig embryo cells, but not mouse L or rabbit kidney cells. The level of activity in guinea pig cells, compared with human WISH cells, was 182% (range 9%-1,900%). These results suggest that the guinea pig may be useful for testing the antiviral, anticancer, or immunomodulatory activity of Hu alpha IFNs in vivo.