Robert B. Couch

Respiratory Viral Infections in Immunocompetent and Immunocompromised Persons

Abstract The acute respiratory illnesses are the most common type of acute illness in the United States today. The respiratory viruses—which include influenza viruses, parainfluenza viruses, respiratory syncytial virus (RSV), rhinoviruses, coronaviruses, and adenoviruses—cause the majority of these illnesses. Some of these viruses cause illness throughout the year, whereas others are most common in winter. All population groups experience these infections and illnesses. As the number of elderly persons and those with underlying disease increases, awareness is growing that these common infections can have serious consequences. This has recently been emphasized for immunocompromised persons. At the M.D. Anderson Cancer Center (MDACC), infection surveillance of mostly hospitalized adults with leukemia or a recent bone marrow transplant yielded a respiratory virus from 181 of 668 (27.1%) respiratory illness episodes. In descending order of frequency, infections with RSV, rhinoviruses, influenza viruses, parainfluenza viruses, and adenoviruses were detected in each of three surveillance years. High frequencies of nosocomial acquisition occurred, as has been noted in prior reports. Similarly, persistence of infection and high frequencies of pneumonia and death among infected patients occurred, which have also been noted earlier. At MDACC, pneumonia occurred in 58–78% of infected patients, and 22–44% died. The role of the virus infection in many cases of pneumonia is uncertain, but death from pure viral pneumonia is well documented. A number of immune deficiencies in this patient population and options for control of these infections have been described that can, respectively, account for the medical problem and provide ways to approach prevention and treatment.

Community Respiratory Virus Infections in Immunocompromised Patients with Cancer

Abstract Community respiratory viruses, such as respiratory syncytial virus (RSV), influenza viruses, parainfluenza viruses, adenoviruses, and picornaviruses, are an important cause of respiratory disease in the immunocompromised adult with cancer. Recent studies have demonstrated that a minimum of 31% of adult bone marrow transplant (BMT) recipients and 18% of adults with leukemia who are hospitalized with an acute respiratory illness have a community respiratory virus infection. The temporal occurrence of these infections in immunocompromised patients tends to mirror their occurrence in the community. The clinical illnesses range from self-limited upper respiratory illnesses to fatal pneumonias, depending on the type of virus and the type and degree of immunosuppression. The pneumonias may be viral, bacterial/fungal, or mixed. The highest frequency of progression to fatal viral pneumonia has been reported for RSV infections in recently transplanted BMT recipients and myelosuppressed patients with leukemia. Studies have suggested that early therapy for RSV pneumonia with a combination of aerosolized ribavirin and intravenous immunoglobulin may be of benefit. Defining effective prophylactic and therapeutic strategies will be a challenge, given the diversity of viruses, the wide spectrum of immunocompromised patients with varying vulnerability to serious community respiratory virus disease, and the frequent presence of other opportunistic infections and medical problems. A combination of antiviral drugs and immunotherapy may need to be considered for their potential additive effect as well as to prevent the emergence of resistant virus, as occurs during monotherapy for influenza with amantadine or rimantadine. The optimal therapies need to be defined in controlled trials; however, it appears that a favorable response will hinge on the initiation of therapy at an early stage of the respiratory illness.

Efficacy of repeated annual immunization with inactivated influenza virus vaccines over a five year period

Some reports have suggested that influenza virus vaccine is less effective in persons that have received prior annual vaccination(s) than in those receiving it for the first time. This issue was addressed by evaluating the efficacy of annual influenza vaccinations over a 5 year period in healthy adults employing commercially-available, inactivated whole-virus vaccine. Influenza vaccination had minimal effects on overall respiratory illnesses during epidemic periods. However, it reduced influenza virus shedding by an average of 38.8% and conferred protection against influenza virus infection during each epidemic. Some variation in infection rates were noted between vaccine groups given one or more than one annual immunization, and between years, but no consistent pattern of differences was noted in relation to number of successive years of vaccination. These results suggest that the current recommendation for annual influenza vaccination of persons at special risk of serious disease and complications is appropriate, but that continued efforts to improve the effectiveness of our prophylactic measures against influenza are needed.

Herpes Zoster-Associated Encephalitis: Clinicopathologic Report of 12 Cases and Review of the Literature

Herpes-zoster associated encephalitis (HZAE) is an uncommon complication of herpes zoster. Over 8 years, we evaluated 12 patients with this clinical diagnosis. The majority of our patients were elderly, immunosuppressed, and found to have disseminated skin lesions prior to the onset of CNS symptoms. All patients had abnormal EEGs, and CSF pleocytosis was found in most. In the seven patients who were tested, specific antibody to the varicella-zoster membrane antigen (FAMA) was detected in spinal fluid during the course of the illness. Although three patients died during the period of active infection, the virus could not be definitively implicated as the cause of death. These HZAE patients could not be distinguished from our other herpes zoster patients on the basis of age, initially involved dermatome, or mortality rate. However, among herpes zoster patients who survived, duration of hospitalization was significantly longer in those with a diagnosis of HZAE. All surviving HZAE patients had a slow but eventual return to their prior cognitive status.

Safety and Immunogenicity of Nonadjuvanted and MF59-Adjuvanted Influenza A/H9N2 Vaccine Preparations

BACKGROUND Influenza A/H9N2 viruses can infect humans and are considered to be a pandemic threat. Effective vaccines are needed for these and other avian influenza viruses. METHODS We performed a phase I, randomized, double-blind trial to evaluate the safety and immunogenicity of a 2-dose schedule (administered on days 0 and 28) of 4 dose levels (3.75, 7.5, 15, and 30 microg of hemagglutinin) of inactivated influenza A/chicken/Hong Kong/G9/97 (H9N2) vaccine with and without MF59 adjuvant. Vaccine safety was assessed with a diary and selected blood tests. Immunogenicity was measured using serum hemagglutination inhibition (HAI) and microneutralization (MNt) antibody assays. RESULTS. Ninety-six healthy adults (age, 18-34 years) were enrolled in the study. Arm discomfort was more common in groups that received adjuvant, but adverse effects of the vaccination were generally mild. Geometric mean serum HAI and MNt antibody titers to the influenza A/chicken/Hong Kong/G9/97 (H9N2) virus strain for all vaccine groups were similar on day 0 but were significantly higher (P<.001) on both days 28 and 56 for the MF59-adjuvanted vaccine groups than for groups given nonadjuvanted vaccine. Other measures of immunogenicity were also higher in the adjuvanted vaccine groups. HAI and MNt geometric mean titers measured after the administration of a single dose of MF59-adjuvanted vaccine were similar to those measured after 2 doses of nonadjuvanted vaccine. CONCLUSIONS The combination of MF59 adjuvant with a subunit vaccine was associated with improved immune responses to an influenza A/H9N2 virus. The adjuvanted vaccine was immunogenic even after a single dose, raising the possibility that a 1-dose vaccination strategy may be attainable with the use of adjuvanted vaccine.

Influenza A virus infection engenders a poor antibody response against the ectodomain of matrix protein 2

BackgroundMatrix protein 2 (M2) is an integral tetrameric membrane protein of influenza A virus (IAV). Its ectodomain (M2e) shows remarkably little diversity amongst human IAV strains. As M2e-specific antibodies (Abs) have been shown to reduce the severity of infection in animals, M2e is being studied for its capability of providing protection against a broad range of IAV strains. Presently, there is little information about the concentration of M2e-specific Abs in humans. Two previous studies made use of ELISA and Western blot against M2e peptides and recombinant M2 protein as immunosorbents, respectively, and reported Ab titers to be low or undetectable. An important caveat is that these assays may not have detected all Abs capable of binding to native tetrameric M2e. Therefore, we developed an assay likely to detect all M2e tetramer-specific Abs.ResultsWe generated a HeLa cell line that expressed full length tetrameric M2 (HeLa-M2) or empty vector (HeLa-C10) under the control of the tetracycline response element. These cell lines were then used in parallel as immunosorbents in ELISA. The assay was standardized and M2e-specific Ab titers quantified by means of purified murine or chimeric (mouse variable regions, human constant regions) M2e-specific Abs in the analysis of mouse and human sera, respectively. We found that the cell-based ELISA was substantially more effective than immobilized M2e peptide in detecting M2e-specific Abs in sera of mice that had recovered from repetitive IAV infections. Still, titers remained low (< 5 μg/ml) even after two consecutive infections but increased to ~50 μg/ml after the third infection. Competition with free M2e peptide indicated that ~20% of M2e-specific Abs engendered by infection reacted with M2e peptide. In humans presenting with naturally acquired influenza virus infection, 11 of 24 paired sera showed a ≥ 4-fold increase in M2e-specific Ab titer. The Ab response appeared to be of short duration as titers were very low (average 0.2 μg/ml) in all patients at onset of infection and in controls, in spite of evidence for previous exposure to IAV.ConclusionThe results provide convincing evidence that M2e-specific Ab-mediated protection is currently lacking or suboptimal in humans.

Adrenal involvement in the antiphospholipid syndrome: clinical and immunologic characteristics of 86 patients.

To describe the clinical and immunologic characteristics of patients with adrenal involvement and antiphospholipid syndrome (APS), we conducted a computer-assisted (PubMed) search of the literature to identify all cases of primary adrenal insufficiency associated with antiphospholipid antibodies published in English, French, and Spanish from 1983 (when APS was first defined) through March 2002.We reviewed 86 patients (80 from the literature plus 6 from our cohort); 55% were male, and the mean age at presentation was 43 ± 16 years. Sixty-one (71%) patients had primary APS, and 14 (16%) had systemic lupus erythematosus. In 31 (36%) patients, adrenal insufficiency was the first clinical manifestation of APS. Abdominal pain was present in 55% of patients, followed by hypotension (54%), fever (40%), nausea or vomiting (31%), weakness or fatigue (31%), and lethargy or altered mental status (19%). The main finding in imaging techniques was compatible with adrenal hemorrhage (59%) and in histopathologic study was a hemorrhagic infarction with vessel thrombosis (55%). Lupus anticoagulant was detected in 97% of patients and the anticardiolipin antibodies titer was positive in 93% of patients. Most patients (95%) were positive for the IgG isotype of anticardiolipin antibodies, whereas 40% were positive for the IgM isotype. Baseline cortisol levels were decreased in 98% of patients, ACTH hormone levels were increased in 96% of patients, and the cosyntropin stimulation test was positive in 100% of patients tested. Steroid replacement therapy was the most frequent treatment (84%), followed by anticoagulation (52%) and aspirin (6%). Thirty-two of 35 (91%) patients with prolonged anticoagulant therapy were in good health with a mean follow-up of 25 months, whereas 25 of the 69 (36%) patients with outcome data available had died.The results of the present review stress the clinical importance of systematic screening for lupus anticoagulant and anticardiolipin antibodies in all cases of adrenal hemorrhage or infarction. An initial screening for hypoadrenalism is mandatory in any antiphospholipid antibody-positive patient who complains of abdominal pain and undue weakness or asthenia.

Dose-Related Safety and Immunogenicity of a Trivalent Baculovirus-Expressed Influenza-Virus Hemagglutinin Vaccine in Elderly Adults

BACKGROUND Influenza-virus hemagglutinin (HA) protein expressed in insect cells by recombinant baculovirus is a candidate influenza vaccine. METHODS In a randomized, double-blind trial conducted in 399 adults > or = 65 years of age, the efficacy of trivalent inactivated influenza vaccine (TIV) licensed for intramuscular injection was compared with that of trivalent baculovirus-expressed HA vaccine administered at doses of 15 microg, 45 microg, or 135 microg of each HA. RESULTS Compared with TIV, baculovirus-expressed HA vaccine was safe and induced better serum antibody responses to the H3 component when administered at doses of 45 microg or 135 microg of each HA. CONCLUSIONS Baculovirus-expressed HA is a safe and immunogenic influenza vaccine in elderly adults.

Early Patterns of Gene Expression Correlate With the Humoral Immune Response to Influenza Vaccination in Humans

BACKGROUND Annual vaccination is the primary means for preventing influenza. However, great interindividual variability exists in vaccine responses, the cellular events that take place in vivo after vaccination are poorly understood, and appropriate biomarkers for vaccine responsiveness have not been developed. METHODS We immunized a cohort of healthy male adults with a licensed trivalent influenza vaccine and performed a timed assessment of global gene expression before and after vaccination. We analyzed the relationship between gene expression patterns and the humoral immune response to vaccination. RESULTS Marked up regulation of expression of genes involved in interferon signaling, positive IL-6 regulation, and antigen processing and presentation, were detected within 24 hours of immunization. The late vaccine response showed a transcriptional pattern suggestive of increased protein biosynthesis and cellular proliferation. Integrative analyses revealed a 494-gene expression signature--including STAT1, CD74, and E2F2--which strongly correlates with the magnitude of the antibody response. High vaccine responder status correlates with increased early expression of interferon signaling and antigen processing and presentation genes. CONCLUSIONS The results highlight the role of a systems biology approach in understanding the molecular events that take place in vivo after influenza vaccination and in the development of better predictors of vaccine responsiveness.

A randomized clinical trial of an inactivated avian influenza A (H7N7) vaccine.

Background Concern for a pandemic caused by a newly emerged avian influenza A virus has led to clinical trials with candidate vaccines as preparation for such an event. Most trials have involved vaccines for influenza A (H5N1), A (H7N7) or A (H9N2). Objective To evaluate dosage-related safety and immunogenicity of an inactivated influenza A (H7N7) vaccine in humans. Design One hundred twenty-five healthy young adults were randomized to receive two doses intramuscularly of placebo or 7.5, 15, 45 or 90 µg of HA of an inactivated subunit influenza A (H7N7) vaccine (25 per group), four weeks apart. Reactogenicity was evaluated closely for one week and for any adverse effect for six months after each dose. Serum hemagglutination-inhibiting and neutralizing antibody responses were determined four weeks after each dose and at six months. Results Reactogenicity evaluations indicated the vaccinations were well tolerated. Only one subject developed a ≥4-fold serum hemagglutination-inhibition (HAI) antibody response and a final titer of ≥1∶40 four weeks after dose two and only five subjects developed a neutralizing antibody rise and a final titer of ≥1∶40 in tests performed at a central laboratory. Four of the five were given the 45 or 90 µg HA dosage. A more sensitive HAI assay at the study site revealed a dose-response with increasing HA dosage but only 36% in the 90 µg HA group developed a ≥4-fold rise in antibody in this test and only one of these achieved a titer of ≥1∶32. Conclusion This inactivated subunit influenza A (H7N7) vaccine was safe but poorly immunogenic in humans. Trials Registration ClinicalTrials.gov NCT00546585