Cytomegalovirus infections in organ transplantation and post transfusion. An hypothesis

Clinical presentation and risk factors for cytomegalovirus colitis in immunocompetent adult patients

BACKGROUND

Cytomegalovirus (CMV) colitis is a common manifestation of CMV end-organ disease, which has typically been described in immunocompromised hosts. Recently, it has been noted that this also occurs in immunocompetent patients. To gather relevant data about clinical presentation, prognosis, and risk factors for development of CMV colitis in immunocompetent hosts, we analyzed all cases that occurred during a 19-year period at our institution.

METHODS

A case-control study was performed to identify risk factors for CMV colitis in immunocompetent hosts. Electronic medical records of individuals who were admitted and diagnosed with CMV colitis between January 1995 and February 2014 at a tertiary care university hospital were reviewed. Two non-CMV colitis patients who were age- and sex-matched were selected as controls for each case.

RESULTS

A total of 51 patients with CMV colitis were included in this study along with 102 control patients. Certain conditions including renal disease on hemodialysis, neurologic disease, rheumatologic disease, intensive care unit admission, and exposure to antibiotics, antacids, steroids, or red blood cell (RBC) transfusions within 1 month of diagnosis of colitis were associated with CMV colitis on univariate analysis. Among these, steroid use and RBC transfusion within 1 month were identified as independent risk factors for developing CMV colitis on multivariate analysis. The 30-day mortality rate was 7.8% without any attributable mortality.

CONCLUSIONS

Steroid use and RBC transfusion within 1 month of the diagnosis of colitis were independent risk factors for development of CMV colitis in immunocompetent hosts.

Allogeneic stimulation causes transcriptional reactivation of latent murine cytomegalovirus

Cytomegalovirus (CMV) reactivation is a well-described complication of transplantation that may be caused by allogeneic stimulation, immunosuppression, or both. These studies were performed to determine if allogeneic stimulation alone is sufficient to reactivate latent CMV. BALB/c mice latently infected with Smith strain murine CMV (MCMV) received allograft (n = 8), allograft plus cortisol (n = 5), or isograft (n = 4) skin. All allograft recipients rejected their grafts within 9 to 12 days of transplantation. Three weeks after grafting, recipients were evaluated for MCMV reactivation, and all allograft recipients (8/8) showed MCMV reactivation, while no isografts had reactivation (0/4). Surprisingly, cortisol therapy blocked MCMV reactivation (0/5). These data suggested that allogeneic stimulation alone can trigger systemic reactivation of latent CMV. Although immunosuppression is thought to contribute to reactivation, certain agents that impair NF-kappaB activation may actually reduce reactivation.

Disruption of murine cardiac allograft acceptance by latent cytomegalovirus

Cytomegalovirus (CMV) reactivation is a well-described complication of solid organ transplantation. These studies were performed to (1) determine if cardiac allograft transplantation of latently infected recipients results in reactivation of CMV and (2) determine what impact CMV might have on development of graft acceptance/tolerance. BALB/c cardiac allografts were transplanted into C57BL/6 mice with/without latent murine CMV (MCMV). Recipients were treated with gallium nitrate induction and monitored for graft survival, viral immunity and donor reactive DTH responses. Latently infected allograft recipients had approximately 80% graft loss by 100 days after transplant, compared with approximately 8% graft loss in naïve recipients. PCR evaluation demonstrated that MCMV was transmitted to cardiac grafts in all latently infected recipients, and 4/8 allografts had active viral transcription compared to 0/6 isografts. Latently infected allograft recipients showed intragraft IFN-alpha expression consistent with MCMV reactivation, but MCMV did not appear to negatively influence regulatory gene expression. Infected allograft recipients had disruption of splenocyte DTH regulation, but recipient splenocytes remained unresponsive to donor antigen even after allograft losses. These data suggest that transplantation in an environment of latent CMV infection may reactivate virus, and that intragraft responses disrupt development of allograft acceptance.

Cytomegalovirus (CMV) antigenaemia for rapid diagnosis and monitoring of CMV-associated disease after bone marrow transplantation

A technique for the rapid detection of cytomegalovirus (CMV) antigen-positive blood leucocytes (CMV antigenaemia) was evaluated in 15 marrow transplant patients as a means of diagnosis and for monitoring CMV-associated disease. CMV antigenaemia was determined by direct immunoperoxidase staining of leucocytes with a peroxidase-labelled monoclonal antibody, HRP-C7, which binds an immediate-early antigen of human CMV. CMV antigenaemia occurred in 7/15 marrow transplant patients (47%) and was initially detected between 4 and 6 weeks after transplantation. CMV-associated diseases developed in 3/15 patients (20%). All patients with CMV-associated disease had a relatively large number of CMV antigen-positive leucocytes, exceeding 10 per 50,000 white blood cells (WBCs). In the remaining 12 patients, CMV antigen-positive leucocytes were less than 10 per 50,000 WBCs or were undetectable. CMV-associated disease did not develop in these patients during the period of monitoring. CMV antigen-positive leucocytes were detected more frequently in patients who developed acute graft-versus-host disease (GVHD) or haemorrhagic cystitis than in those without such complications. CMV antigens were detectable from 1 to 4 weeks before the onset of CMV-associated disease which allowed initiation of ganciclovir treatment at an early stage. The degree of CMV antigenaemia paralleled the clinical symptoms and signs, higher degrees of antigenaemia being associated with more significant disease. Thus, the detection of CMV antigen-positive blood leucocytes is useful for the diagnosis and monitoring of CMV-associated disease following bone marrow transplantation.

Reactivation of cytomegalovirus in patients with cirrhosis: analysis of 122 cases

Human cytomegalovirus causes severe and often fatal infections in immunocompromised patients. After organ transplantation cytomegalovirus in peripheral blood mononuclear cells is thought to be activated by alloreaction and to spread because of immunosuppression, and it may cause endogenous cytomegalovirus diseases. Patients with cirrhosis, one group of candidates for liver transplantation, often show various grades of immunosuppression before transplantation. To evaluate the status of cytomegalovirus infection in cirrhotic patients and its relevance to the degree of immunosuppression, we examined the presence of cytomegalovirus in mononuclear cells by polymerase chain reaction and immunocytochemical analysis. We studied 122 patients with definite cirrhosis and 43 normal volunteers. All cirrhotic patients (100%) and 40 (93%) of 43 normal controls were seropositive for cytomegalovirus. Cytomegalovirus DNA was detected by polymerase chain reaction in 77 (63.1%) of 122 seropositive cirrhotic patients, but in only 1 (2.5%) of 40 seropositive normal controls (p < 0.01). Cytomegalovirus antigen could not be detected in mononuclear cells by immunocytochemical staining with monoclonal antibodies. Cytomegalovirus DNA-positive patients have a greater impairment of liver function than do cytomegalovirus DNA-negative patients; this fact is manifested by delayed indocyanine green retention rates and elevated serum bilirubin levels (p < 0.05). Lymphocyte proliferative response induced by phytohemagglutinin and natural killer cell activity were also significantly lower in cytomegalovirus DNA-positive patients as compared with cytomegalovirus DNA-negative patients (p < 0.01). Our data suggest that the reactivation of cytomegalovirus may have already occurred in patients with cirrhosis before transplantation.

Transfusion-acquired cytomegalovirus infection in children in a hyperendemic area

Thirty-nine children without previous cytomegalovirus (CMV) infection received blood transfusion in the National Taiwan University Hospital. The overall transfusion-acquired CMV infection rate was 36% (14/39). Donor CMV seropositive rate was 70%. None of the nine children who had received seronegative blood became infected, in contrast to 14 of the 21 children (67%) who had received seropositive blood (P = 0.002). Another significant risk factor associated with CMV infection was the use of fresh blood: 13 of 15 (87%) with fresh seropositive blood were infected, in contrast to one of six (17%) with "old" seropositive blood (P = 0.01). Most of the fresh blood was used within 24 hours. This blood processing method was shown to account for the extremely high rate of CMV infection in those who had received fresh seropositive blood. The results indicated that the incidence of CMV infection can be reduced by avoiding the use of fresh blood, especially blood less than 24 hours old. For such a population in Taiwan with high prevalence of positive CMV antibody, this approach was more applicable than screening donor blood for CMV antibody.

Acquisition of cytomegalovirus infection: an update

Human cytomegalovirus (CMV) is a ubiquitous deoxyribonucleic acid virus that commonly infects a majority of individuals at some time during their life. Although most of these CMV infections are asymptomatic, certain patient groups are at risk to develop serious illness. Understanding the epidemiology of this virus is a key element in the development of strategies for preventing CMV disease. However, a number of features of this virus complicate such understanding. Following infection, CMV can remain latent, with subsequent reactivation; the factors controlling latency and reactivation and those factors which determine whether a CMV infection will be symptomatic are unknown. CMV disease can be acquired by natural routes, including horizontal and vertical transmission. Due to the ubiquity of CMV, the delineation of CMV transmission by these natural routes is complicated by the myriad of possible sources. Moreover, concerns over the risk of CMV transmission to the seronegative pregnant female have been raised in relation to preventing CMV transmission. By using molecular biologic techniques, much knowledge has been gained regarding the transmission of CMV disease by natural routes; however, a number of questions remain unanswered. The transmission of CMV infection by natural routes is therefore reviewed and the issues are highlighted. Primary infection, reactivation, and reinfection are the types of active CMV infections that can occur in an immunocompromised patient. In addition to natural routes of infection, introduction of presumably latently infected organs and requirements for multiple blood transfusions increase potential exposure to CMV in the immunocompromised patient. Understanding the epidemiology of CMV infections in the immunocompromised patient is difficult and in some instances controversial due to the complexity and interdependency of a number of factors which lead to CMV infection. In an immunocompromised individual, a major risk factor in developing overt CMV-related disease is associated with the serological status of an organ donor, the recipient, and the blood product given to these patients. In addition, a large body of inferential data supports the transmission of CMV by blood products or organs from seropositive donors; however, the mechanisms by which transmission occurs remain unclear. The possible sources and mechanisms of transmission of CMV infections in the immunocompromised host are reviewed. Lastly, strategies for the ultimate prevention of CMV disease are discussed in light of the epidemiology of CMV infections. To date, these strategies have included use of CMV-seronegative blood products or organs, antiviral agents, and vaccines.(ABSTRACT TRUNCATED AT 400 WORDS)

Transfusion-transmitted cytomegalovirus infections: significance and control

Cytomegalovirus (CMV) is a herpes virus which can give rise to primary infections, reactivated infections, or reinfections in humans. Seroepidemiologic studies have shown CMV infection to be worldwide with the highest antibody prevalences detected in Third World countries; however, significant regional variations can be seen within a given country. Antibody prevalence varies directly with age and inversely according to socioeconomic status. Numerous prospective studies of blood transfusion recipients carried out since 1966 have shown marked differences in infection rates but relatively little associated disease. Infection rates were highest in seronegative recipients given large amounts of fresh blood. Recently published reports have shown substantially lower infection rates than earlier studies, a change likely to be due to the current practice of transfusing fewer units of older blood. CMV has not been found to play a significant role in the etiology of posttransfusion hepatitis. CMV infections have been found to be an important source of morbidity and mortality in immunocompromised patients. Several studies of transfused, premature infants have shown significant differences in infection rates and disease expression. Seronegative low-birth-weight infants receiving blood from seropositive donors are at greatest risk. Blood from CMV-seronegative donors substantially lowers the risk of infection. Receiving a kidney or heart from a CMV-seropositive donor appears to be a more salient risk factor than blood transfusion in renal and cardiac transplant patients who are also more likely to have symptomatic CMV infections. Leukocyte transfusions have been found to be a significant source of CMV infection and disease in bone marrow transplant patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Transfusion-acquired cytomegalovirus infection in cardiac surgery patients

The incidence of transfusion-acquired primary cytomegalovirus (CMV) infection was studied in 483 cardiac surgery patients. Ninety-six patients (20%) were found to lack antibody to CMV [CMV Ab(-)] as measured by radioimmunoassay. Sixty-eight CMV Ab(-) were followed by viral culture and/or serology from eight weeks to one year after transfusion. Transfusion requirements in CMV Ab(-) patients were as follows: whole blood/packed red blood cells, mean 4.7 +/- 2.6 units; platelets (20 patients), 6.9 +/- 3.8 units; fresh frozen plasma (25 patients), mean 3.3 +/- 1.6 units. Forty-nine percent of 235 donor units tested had antibody to CMV. One donor unit (0.4%) had CMV-specific IgM. This was not associated with CMV infection in the recipient. One patient (1.5%) demonstrated evidence of seroconversion to CMV during the follow-up period. This is significantly less than reported in previously published studies (P less than .01). Serological methods used, the age of the transfused blood, the immune status of the transfusion recipient, and the administration of passive antibody in fresh frozen plasma are factors that may be responsible for the low incidence observed.

Prevalence of cytomegalovirus antibody in nursing personnel

To evaluate the risk to nurses of childbearing age of acquiring cytomegalovirus (CMV) infection during the care of patients at high risk of the infection, 374 female hospital employees (288 nursing personnel) were interviewed and screened for antibody to CMV. Fifty-six percent of the population surveyed had antibody to CMV as measured by an immunofluorescent assay. Among nursing personnel, analysis of antibody prevalence by job title, work area, and duration of work showed no association between seropositivity and either current or past exposure to "high-risk" patients, such as infants and immunosuppressed individuals. Age, race (non-white), and the number of pregnancies reported by participants were significantly associated with the presence of antibody. Among 73 employees of a children's hospital, the prevalence of CMV antibody was 41%. This survey suggests that hospital nursing is not a major risk factor for acquiring CMV infection. However, this finding needs further evaluation in a prospective study of seroconversion rates among seronegative nurses.

Comparison of enzyme-linked immunosorbent assay, radioimmunoassay, complement fixation, anticomplement immunofluorescence and passive haemagglutination techniques for detecting cytomegalovirus IgG antibody

The radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) techniques were found to be comparable in sensitivity and specificity for detecting cytomegalovirus IgG antibody, and 10 to 100 times more sensitive than complement-fixation (CF), anticomplement immunofluorescence (ACIF) and passive haemagglutination (PHA). In screening tests for antibody, the frequency of false-positive and -negative results was 0.6% for RIA and ELISA, 1.5% for CF, 1.6% for ACIF and 3.6% for PHA. PHA was the least satisfactory test, largely because of technical problems. Cytomegalovirus (CMV) infection is an important cause of congenital brain damage and is also a major complication of both prolonged immunosuppressive therapy, especially in patients with organ transplants, and multi-donor blood transfusions. For serological diagnosis of infection, as well as for screening for antibody in patients and in blood donors, the solid-phase indirect radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) techniques offer distinct improvements in sensitivity over previous methods. Although the principle of both tests, based on the detection of antigen-antibody reactions by means of a labelled anti-antibody, is the same, each possesses its own particular technical advantages and disadvantages, and both require their own expensive equipment for the reading of the results. There is still a lack of data on how they compare in sensitivity and specificity. The present study was undertaken to compare the two methods for the detection of CMV IgG and to evaluate them against the older techniques of complement-fixation (CF), passive haemagglutination (PHA) and anticomplement immunofluorescence (ACIF).

Spontaneous activation of latent cytomegalovirus from murine spleen explants. Role of lymphocytes and macrophages in release and replication of virus

Cytomegalovirus (CMV) is a major pathogen in the compromised host where many infections result from activation of latent virus. Because latent CMV infection has been difficult to study in humans, murine models have been developed and investigated. Here, we describe the events involved in activation of latent murine CMV (MCMV) from spleen explants in vitro. Infectious virus was no longer detectable in murine organs 4 mo after inoculatioN of 10(5) plaque-forming units of MCMV. 8-10 d after establishment of spleen explants, phagocytic macrophages covered 70-80% of the surface of tissue culture dishes, and lymphocytes were continuously released, reaching titers of 10(6) cells/ml. MCMV was produced spontaneously after 12-18 d from spleen explant cultures of 33 of 34 mice. Virus replicated to titers above 10(4) plaque-forming units/ml, remained at that level for 4-5 wk, and gradually disappeared as macrophages were lysed. Although MCMV was shown to be replicating in macrophages, these cells were never found to be the source of latent virus. Cell separation studies indicated that latent virus was initially released from 70% of lymphocyte cultures and was associated with the B cell enriched fraction. We conclude that MCMV establishes nonreplicating dormant infection in B lymphocytes, activates from these cells in spleen explant cultures, and is augmented in titer by replication in permissive macrophages.

Temporal patterns of human cytomegalovirus transcription: mapping the viral RNAs synthesized at immediate early, early, and late times after infection

The transcription of the human cytomegalovirus genome was investigated at immediate early, early, and late times after infection. Viral RNAs associated with either the whole cell, the nucleus, the cytoplasm, or the polyribosomes were analyzed. At immediate early times, i.e., in the absence of de novo viral protein synthesis, the viral RNA in high abundance originated from a region of the long unique section of the prototype arrangement of the viral genome (0.660 to 0.770 map units). The viral RNA in low abundance originated from the long repeat sequences (0.010 to 0.035 and 0.795 to 0.825 map units) and a region in the long unique section (0.201 to 0.260 map units). Viral RNAs associated with the polyribosomes as polyadenylated RNA were mapped to these restricted regions of the viral genome and characterized according to size class in kilobases. At 24 h after infection in the presence of an inhibitor of viral DNA replication, i.e., at early times, the stable viral RNAs in highest abundance mapped in the long repeat sequences. Viral RNAs at intermediate abundance under these conditions mapped in two regions of the long unique section of the viral genome (0.325 to 0.460 and 0.685 to 0.770 map units). Stable viral RNAs that were associated with the polyribosomes in high abundance as polyadenylated RNA orginated from the long repeat sequences, but not from the long unique section of the viral genome. An analysis of whole-cell RNA at late times (72 h) indicated that the abundant transcription was in the regions of the long unique sequences (0.325 to 0.460 and 0.660 to 0.685 map units), and transcription of intermediate abundance was from the long repeat sequences. However, stable viral mRNA's derived from the long repeat sequences were associated with the polyribosomes at late times after infection. In addition, mRNA's originating from the long and short unique sequences were found associated with the polyribosomes at higher relative concentration than at early times after infection. It is proposed that expression of the immediate early viral genes is required to transcribe the early viral genes in the long repeat and adjacent sequences. These sequences are also transcribed at late times after infection while viral DNA synthesis continues. The expression of viral genes in most of the long and short unique sequences appears to require viral DNA replication.

Temporal regulation of human cytomegalovirus transcription at immediate early and early times after infection

The immediate early transcripts of human cytomegalovirus originated from restricted regions of the viral genome. In contrast, transcription at early times was complementary to all regions of the viral genome that were fractionated by restriction endonuclease treatment followed by agarose gel electrophoresis. The viral genome was also extensively transcribed when 2 h of protein synthesis or longer was permitted after infection in permissive cells treated with an inhibitor of viral DNA replication or in nonpermissive cells of animal origin that permit little or no viral DNA replication. The size and in vitro translation products of the cytomegalovirus-specified mRNA's at immediate early and early times after infection were determined. Discrete size classes of virus-specified polyadenylated RNA accumulated on the polyribosomes of cells infected in the presence of an inhibitor of protein synthesis. When 2 or 24 h of protein synthesis occurred after infection, there were changes in the relative abundance of the virus-specified RNAs that accumulated on polyribosomes. Treatment of nonpermissive cells had little effect on the size classes of viral RNA found associated with the polyribosomes at early times after infection. These viral mRNA's were assumed to represent early viral gene expression. In vitro translation of the viral mRNA isolated from polyribosomes at immediate early and early times after infection identified many of the virus-specified gene products and demonstrated (i) a switch from immediate early to early viral gene expression and (ii) a prolonged phase of early viral gene expression. The data also indicated that the initiation of viral RNA synthesis does not depend on the formation of viral protein, but that de novo viral protein synthesis may influence the extent of transcription of the viral genome.

DNA nucleotide sequence heterogeneity between the Towne and AD169 strains of cytomegalovirus

The results of reciprocal DNA-DNA reassociation kinetics indicated that although the DNAs of human cytomegalovirus (CMV) strains Towne and AD169 shared approximately 90% of their nucleotide sequences, about 10% heterogeneity did exist. The implication was that, with respect to one another, the DNAs of CMV Towne and CMV AD169 contained unique nucleotide sequences. To obtain more direct evidence, 32P-labeled DNA of one virus strain was reassociated in the presence of excess unlabeled DNA of the heterologous virus strain. Those 32P-labeled DNA sequences remaining single stranded were separated from double-stranded DNA on hydroxyapatite columns and incubated with Southern blots containing XbaI restriction enzyme fragments of the homologous virus DNA. This approach not only enriched for nucleotide sequences unique to each strain of virus, but also provided for the identification of the restriction enzyme fragments in which the unique sequences were contained. The CMV Towne unique sequences were found in XbaI fragments A, C, G, L, N, and Q of CMV Towne DNA. The CMV AD169 unique sequences were found in XbaI fragments A, C, G, and J of CMV AD169 DNA. The possible significance of these data with respect to variation among other CMV isolates is discussed.

Prophylactic granulocyte transfusions during human bone marrow transplantation

Thirty-eight uninfected patients undergoing bone marrow transplantation were assigned at random to receive prophylactic granulocyte transfusions and oral nonabsorbable antibiotics (group 1) or oral nonabsorbable antibiotics alone (group 2) when their neutrophil count fell below 0.5 x 10(9)/liter. The two groups were comparable in terms of age, sex, underlying disease, immunosuppressive therapy and days of neutropenia. There were three cases of septicemia (all due to gram-positive organisms) in group 2 and none in group 1 (p = 0.23). There was no difference in the incidence of other documented infections, and survival between the two groups was comparable. Recipients of prophylactic granulocyte transfusions had a significantly higher incidence of cytomegalovirus (CMV) infections (13 of 18 versus six of 17, p = 0.043). These data suggest that prophylactic granulocyte transfusions may prevent septicemia, have no effect on other infections or survival in patients undergoing bone marrow transplantation, and are associated with a higher incidence of CMV infection. Oral nonabsorbable antibiotics alone are equally effective in preventing serious infections in bone marrow transplant recipients.

Cytomegalovirus excretion in gnotobiotic pigs

Germ-free piglets were infected intranasally with porcine cytomegalovirus (PCMV) at 1 day (group A) or 3 weeks of age (group B). Viraemia and virus excretion by the nasal, pharyngeal and conjunctival routes was studied up to the time of death or to 12 weeks. Virus was also sought in tissues at death or at slaughter, as well as in a few urine samples. Viraemia was detected in group A between days 5 and 19 after infection and in group B between days 14 and 16 inclusive. The chief route of virus excretion was the nasal mucosa, followed by the pharynx and conjunctiva; the maximal duration of excretion by these routes was 32, 25 and 14 days for pigs of group A and 9, 7 and 4 days for group B. The quantity of virus was also greater in the former group, of which died of generalized PCMV infection. A viruria was demonstrated in 2 animals. Antibody detectable in indirect immunofluorescence (IIF) tests appeared towards the end of the third week, reaching maximal titres at 5 to 7 weeks after infection. The mean peak titre of antibody in group B was lower than in group A. Corticosteroid treatment at days 56--62 after infection resulted in some recrudescence of virus excretion, accompanied in group B by about a twofold increase in IIF antibody. PCMV was isolated in cultures of lung macrophages from 4 of 7 animals killed at about 12 weeks after inoculation.

Lymphocyte response to blood transfusion in man: a comparison of different preparations of blood

The appearance of atypical lymphocytes in post-transfusion blood, their incorporation of tritiated thymidine in tissue culture and the elimination of cytotoxic antibody production, have been used as markers to show that frozen red cells are the least immunogenic when compared with dextran sedimented blood and whole blood donations. The absence of atypical lymphocytes and failure to produce lymphocytotoxic antibodies after transfusion of frozen cells is highly significant (P is less than 0.001) when compared with whole blood donations.

Enhancement of mouse cytomegalovirus infection during host-versus-graft reaction

C3H/He mice chronically infected with murine cytomegalovirus were given skin allografts from histoincompatible BALB/c donors. A significant increase in cytomegalovirus titers occurred within 3 days after placement of the graft in the spleens and kidneys of the allograft recipients as compared with control animals. No significant changes in virus titers were detected in the salivary gland, lung, liver, or blood of allograft recipients. These results indicate that the host-versus-graft reaction alone can enhance murine cytomegalovirus in a chronically infected host and may help explain the high incidence of cytomegalovirus infection seen after renal and other allograft transplantation in man.