Human immunodeficiency virus type 1 infection in homosexual men who remain seronegative for prolonged periods

Host-virus interaction as defined by amplification of viral DNA and serology in lentivirus-infected sheep

To correlate the presence of ovine lentivirus (OvLV) as detected by polymerase chain reaction (PCR) with detection of antibody, 42 sheep from a flock with enzootic OvLV infection were studied. The results of agar gel immunodiffusion (AGID), ELISA, and immunoblotting assays were compared, and leukocytes (blood, bone marrow, lymph node, and lung cells) were assessed for viral DNA by PCR using pol and LTR primers; amplified products were detected by specific DNA and RNA probes. Based on the number of animals that had detectable viral DNA, the specificities of AGID, ELISA, and immunoblotting were 77%, 92%, and 95 or 100% (depending on which criterion was used to interpret immunoblot results), respectively. Only in animals with OvLV-associated disease was OvLV DNA detected in leukocyte DNA prior to the amplification of virus in culture and only in this group was high titer antibody detected to the OvLV major surface (gp 105) and transmembrane (gp 55) antigens. Animals that were both antibody and PCR-negative lacked histopathologic evidence of disease. From this study there was no indication that OvLV infection without the development of antibody occurs, and detection of OvLV DNA in animals with weak or partial serological reactions likely indicates early OvLV infection rather than false-positive PCR results.

Failure to detect silent HIV infection by polymerase chain reaction in subjects at risk for heterosexually transmitted HIV type 1 infection

The prevalence of silent HIV-1 infections in subjects at risk of acquiring HIV infection by heterosexual transmission was assessed using a nested polymerase chain reaction (PCR) assay. The two groups of risk subjects consisted of 92 female prostitutes and 43 heterosexual partners of infected individuals. Appropriate positive and negative control persons were included in the study. Serum samples were also tested for antibody to HIV-1 by an enzyme immunoassay (EIA) and positive results confirmed by Western blot. PCR results in the two risk groups and the positive and negative controls were in full agreement with serological results. It is concluded that silent infection with HIV-1 is infrequent in persons at risk for heterosexual transmission.

The infectious risks of transfusions in the United States: a decision-analytic approach

INTRODUCTION

The development of AIDS as a result of HIV transmission and of cirrhosis as a result of chronic non-A, non-B hepatitis are the greatest infectious risks associated with transfusion in the United States. The goal of this study is to provide explicit quantitative guidelines to determine when the risk of death from all causes associated with transfusion exceeds the risk associated with anemia.

METHODS

This study uses a decision-analytic model.

RESULTS

On the basis of reported transfusion complication rates and an independent worst-case calculation of the risk of AIDS and non-A, non-B hepatitis, transfusion with red blood cells should be recommended as long as each unit received reduces the patient's risk of dying from anemia by at least 1/1100.

DISCUSSION

Because of the relative safety of the blood supply as a result of universal screening and donor deferral, the overestimation in practice of fatal infectious complications, and the possible underestimation of the risk of anemia, undertransfusion has the potential to be as serious a problem in the United States as is overtransfusion. Although caution should be exercised not to undertransfuse when a patient has an appreciable risk of anemia-associated death, we must be wary not to overtransfuse for temporary relief of morbidity.

Detection of feline immunodeficiency virus proviral DNA in feline peripheral blood mononuclear cells by the nested two-step polymerase chain reaction

The polymerase chain reaction (PCR) was applied to detect feline immunodeficiency virus (FIV) proviral DNAs in primary peripheral blood mononuclear cells (PBMC). Suitable conditions for PCR amplification were examined to obtain highly sensitive and specific results by simple staining in agarose gel. Specific amplification of FIV proviral DNA in PBMC DNA of FIV-infected cats was achieved by a nested two-step PCR that amplified the DNA first with outer primers and then with inner primers nested within the first primers. PCR amplification using different primers indicated that those based on the gag sequence of the FIV/TM2 strain isolated in Japan were suitable for the detection of FIV genomes in naturally infected Japanese pet cats. By the nested two-step PCR with mixed gag primers of TM2 and Petaluma, isolated in the USA, we could detect FIV genomes in all 11 primary PBMC samples from FIV-seropositive cats tested. The PCR protocol developed here is sensitive and specific for molecular detection of FIV infection in cats.

Prevention of transmission of HIV by organ and tissue transplantation. HIV testing protocol and a proposal for recommendations concerning donor selection

Human immunodeficiency virus (HIV) can be transmitted by solid organ and some forms of tissue transplantation. Although routine screening of organ and tissue donors for anti-HIV antibodies was implemented in most Western European countries and North America in 1985, several recent case reports indicate that a definite, albeit very small, risk of HIV transmission still remains. The screening tests that are currently used cannot rule out a false-negative test result occurring during the window period. Moreover, massive transfusion of the donor during the donor procedure may result in an undetectable anti-HIV antibody titer (by dilution of donor blood) that consequently leads to a false-negative test result. These risks of HIV transmission via transplantation and important issues in HIV testing are discussed in detail. Furthermore, several recommendations for the prevention of transmission and a protocol for HIV testing for both organ and tissue donation are presented. These may serve as intermediary guidelines until official ones, such as already exist for blood donation, are defined by the transplantation communities. The exclusion of donors whose behavior may place potential recipients at risk for HIV infection is essential. A thorough heteroanamnesis of the donor's next of kin during the donor procedure should provide sufficient information about donor history to enable a decision to be made in this respect. Special attention is given to the question of whether the existing donor selection criteria for blood donation should be applied in a similar way to organ donation since the strict application of selection criteria may limit the number of available donor organs.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of HIV-1 by polymerase chain reaction and culture in seronegative intravenous drug users in an inner-city emergency department

STUDY BACKGROUND

After a health care worker's unprotected exposure to a patient's blood, the current recommendation is to obtain consent from the source for serologic testing for HIV. If the test is negative, no further follow-up of the exposed provider is usually indicated.

OBJECTIVE

To determine if patients testing negative for HIV-1 antibody on routine serology harbor occult HIV-1 infection.

DESIGN

Cross-sectional, identity-unlinked, patient-related data and blood sample procurement for HIV-1 infection.

SETTING

Inner-city university hospital emergency department with high HIV-1 seroprevalence among patients.

TYPE OF PARTICIPANTS

IV drug users not known to have HIV-1 infection.

MEASUREMENTS

Serum samples were analyzed for HIV-1 antibodies by enzyme immunoassay and Western blot. Peripheral mononuclear cells were analyzed for HIV-1 provirus by polymerase chain reaction and viral culture.

MAIN RESULTS

Of 131 patients, 36 (27.5%) were Western blot-confirmed seropositive for HIV-1. Of the 95 seronegative patients, six (6.3%) were polymerase chain reaction positive, and one of these was confirmed with culture. The negative predictive value of standard serology was 93.5% with polymerase chain reaction alone and 98.9% with concordant polymerase chain reaction and culture results.

CONCLUSION

There may be a significant number of ED patients in HIV-1 prevalent populations who have occult HIV-1 infection not detectable by serology at the time of a health care provider exposure. Although these data suggest that further prospective study is warranted to better quantify the frequency of this phenomenon, these preliminary data suggest that current Centers for Disease Control recommendations regarding provider exposures may need to be reappraised for certain situations.

Virus isolation, polymerase chain reaction and in vitro antibody production for the diagnosis of pediatric human immunodeficiency virus infection

Viral culture (VC), polymerase chain reaction (PCR) and in vitro antibody production (IVAP) by peripheral blood mononuclear cells were compared for the early diagnosis of HIV-1 infection in 46 infants born to HIV-1 seropositive mothers. The ten children considered infected on the basis of clinical signs and persistence of anti-HIV-1 antibodies had at least one positive viral culture and seven were always positive in both PCR and IVAP tests. PCR and IVAP tests were occasionally negative in three infected children. Among 30 healthy children who became seronegative and were always negative for viral culture, 22 (73.3%) were also repeatedly negative in PCR and IVAP. We report 6 cases of children classified as P2A at the term of this study but who had lost anti-HIV-1 antibodies. They presented at least one positive viral culture and occasional positive PCR and/or IVAP results. The results indicate that the combination of viral culture, PCR and IVAP tests improves the early diagnosis of pediatric HIV infection.

Silent HIV infection

The period of latency between infection by the human immunodeficiency virus type-1 (HIV-1) and the production of specific antibodies to viral antigens may be prolonged and, occasionally, may last for years. This condition of seronegative infection could represent a serious risk of viral transmission from subjects who are unaware of their status. However, whether these individuals are actually infectious, especially through body fluids, has not been clarified. We have performed a prospective study in 65 high-risk individuals seronegative for HIV-1 antibodies for a prolonged period of time. Twelve of them (18%) were shown to be carriers of HIV-1 proviral sequences by the polymerase chain reaction (PCR). The virus was isolated from mitogen-stimulated peripheral blood lymphocytes in five out of ten subjects tested since the first positive PCR. In two of them, virus could also be isolated from cell-free plasma, subsequently they remained seronegative during 10 months of follow-up. These data indicate that delayed seroconversions may be associated with productive infection, suggesting that mechanism(s) other than viral latency may be responsible for the absence of antibody responses to HIV-1 proteins. Furthermore, our findings suggest that prolonged seronegative individuals can transmit HIV infection through their body fluids.

Enzyme-linked immunosorbent assays for the measurement of human immunodeficiency virus, type 1 reverse transcriptase antigen and antibodies

Enzyme-linked immunosorbent assays (ELISA), using recombinant HIV-1 reverse transcriptase (RT; p66), are described for the measurement of RT antigen and serum antibodies to RT (anti-RT). The ELISA for anti-RT was developed in qualitative and quantitative forms, both were highly specific (100%, 0/859; 99.6%, 3/859), the former was sensitive (100%, 364/364) detecting the highest dilution of a standard high titre anti-HIV-1 RT antibody positive control serum. The latter was less sensitive (97.2%, 354/364) detecting lower dilutions of the antibody control, but had the advantage of producing highly reproducible optical density/concentration curves for the quantification of unknown anti-RT samples. In a cross-sectional study of 191 patients with HIV-1 infection, all patients developed anti-RT antibodies in CDC disease group II and III that declined but persisted in all cases into CDC disease group IV. The RT antigen assay was specific (100%, 0/772) and sensitive detecting 6 to 15 pg/ml of recombinant RT antigen diluted in normal human serum. No cross-reactivity using the RT antibody and antigen assays was seen in sera from 85 patients with current or previous hepatitis B infection or 21 sera from patients with HIV-2 infection. Further, no reactivity was demonstrated with the assays in a cohort of 20 seronegative partners (320 samples) exposed to HIV-1 infection over a 4-yr period. In samples from a patient with documented seroconversion, RT antigen was the first detectable marker of HIV-1 infection and was followed by a prompt anti-RT response. Serum RT antigen disappeared or remained low in most patients during CDC disease group II and III and rarely reappeared with progression to CDC disease group IV. In tissue culture studies RT antigen was detected in supernatant within 12 h (75 pg/ml), gave an initial peak at 36 h (300 pg/ml) and then continued to rise up to 5 days (603 pg/ml), offering a simple, cost-effective alternative to existing methods.

Persistently human immunodeficiency virus type 1-infected T cell clone expressing only doubly spliced mRNA exhibits reduced cell surface CD4 expression

Several cell clones possessing the human immunodeficiency virus type 1 (HIV-1) genome, consisting of an almost full-length DNA sequence, were isolated by limiting dilution of the clonal cell line M10 derived from MT-4 that survived infection with HIV-1 vpr mutant (M10/vpr-). One of the isolated clones (termed Vpr-1) expressed only doubly spliced mRNA, but not unspliced or singly spliced mRNA. Western blots of Vpr-1 revealed the presence of the nef translation product, although no expression of major structural genes such as gag, pol, and env was detected by indirect immunofluorescence and assay of reverse transcriptase activity. These HIV-1 phenotypes differed greatly from those of the original M10/vpr-, most of which expressed major structural HIV-1 proteins. Despite undetectable levels of env expression in Vpr-1, CD4 antigens were greatly down-modulated on the surface without alteration of steady-state levels of CD4 mRNA expression, similar to M10/vpr-. These HIV-1 phenotypes in Vpr-1 did not change after the treatment of the cells with both phorbol 12-myristate 13-acetate and phytohemagglutinin. Therefore, the abnormal HIV-1 life cycle in Vpr-1 seems to be due to some viral factor(s), as well as cellular factors. Thus, Vpr-1 could be a useful model for understanding one HIV-1 latent form.

Polymerase chain reaction and transfusion microbiology

Polymerase chain reaction (PCR) involves alternate denaturing and re-annealing of DNA in test samples in the presence of appropriate oligonucleotide primers complementary to opposite strands of the target DNA together with a heat-stable DNA polymerase, Mg2+ and the four nucleotide triphosphates. DNA target segments can be 'amplified' ten-millionfold by 25-35 such cycles. Even greater amplification (approximately 10(12)-fold) with enhanced specificity can be obtained by a second set of amplification cycles using a further pair of 'nested' primers sited within the DNA sequence defined by the original primers. PCR can be applied to the study of the whole range of transfusion-transmitted infections, both plasma and cell associated; RNA viruses can be analyzed if a DNA copy is made from the viral RNA by treatment with reverse transcriptase. In a transfusion context, the retroviruses (HIV-1, HIV-2, HTLV-I, HTLV-II), HCV and HBV have been the viruses most intensively subjected to PCR analysis. The advantages of PCR in this context include its ability to detect virus during the 'window period' or seronegative stages of infections and its value as a marker for viraemia and for the detection of viruses in products made from large pools of plasma. True immunity may also be differentiated from persistent infection in the presence of antibody. Similarly, PCR can overcome problems of diagnosis of acute infection caused by the presence of passively transferred antibody. Detailed strain differentiation is also possible by PCR, in conjunction with sequencing or with the aid of restriction endonucleases.(ABSTRACT TRUNCATED AT 250 WORDS)

Elevated levels of soluble CD54 (ICAM-1) in human immunodeficiency virus infection

Soluble CD54 levels in sera were quantitated in asymptomatic intravenous drug users, homosexuals, and patients with lymphadenopathy, AIDS-related complex, or acquired immunodeficiency syndrome. Soluble CD54 levels were elevated in human immunodeficiency virus (HIV)-seronegative asymptomatic intravenous drug users, reflecting infections like cytomegalovirus, Epstein-Barr virus, and hepatitis B virus. The sera of human immunodeficiency virus-seropositive groups of patients also had elevated levels of soluble CD54, reflecting infections like cytomegalovirus and human immunodeficiency virus infection.

Detection of HIV-1 infections by PCR: evaluation in a seropositive subject population

To study the polymerase chain reaction (PCR) performance in detecting human immunodeficiency virus (HIV) infections, we tested 53 HIV-1 seropositive patients and 29 HIV-1 seronegative subjects for four different HIV-1 DNA regions. Fifty-one seropositive patients were found positive by PCR with at least one primer pair, but two were repeatedly negative for all primers. Weekly blood samples from 12 seropositive subjects all detected positive for at least one primer pair, but for three patients an irregular primer detection pattern was found. One additional HIV-1 seropositive sample, found negative for HIV DNA, was also negative for the beta-globin PCR control. The 29 seronegative specimens were HIV-1 DNA negative, as was a HIV-2 seropositive patient. This study demonstrates that PCR is almost as good as serological tests for detecting HIV infections, with a specificity of 100% and a sensitivity of 96% and that resampling the patients may improve detection performance.

'Silent' HIV infection among wives of seropositive HIV carriers in the Ethiopian community in Israel

We have previously described the phenomenon of 'silent HIV carriers', i.e. individuals with HIV specific immunity and a positive PCR for HIV-1, yet HIV seronegative. In the present study, we have looked for such 'silent' carriers among wives of individuals infected with HIV in Africa (Ethiopia). In addition to determining HIV serology, peripheral blood mononuclear cells (PBMC) were tested by PCR for HIV-1 and for their ability to generate specific antibodies to HIV upon polyclonal B-cell activation (P-BAT). Out of 16 wives so tested, three were HIV seropositive and among the 13 seronegatives, eight were P-BAT positive and five were both P-BAT and PCR positive. These findings suggest that (1) 'silent' HIV carriers may indeed be present in African populations; (2) interpretation of the 'silent' carrier phenomenon is not clear and will depend on clinical follow-up and the ability to culture virus from such carriers; and (3) results of HIV serology in this population and probably in other African populations should be viewed with caution.

Detection of ovine lentivirus in seronegative sheep by in situ hybridization, PCR, and cocultivation with susceptible cells

Serological surveys for ovine lentivirus (OvLV), a worldwide cause of pneumonia and chronic debilitation in sheep, have demonstrated a wide range of seroprevalence rates. This study analyzed OvLV infection in a purebred sheep flock with a history of OvLV disease (flock 1), and compared the prevalence with that of a flock lacking previous OvLV-associated disease (flock 2). Serological tests (ELISA and Western blot assay) indicated that 25% of sheep of all ages in flock 1 (Group A) and 33% of animals of all ages in flock 2 (Group B) had antibodies to OvLV. In situ hybridization, however, detected viral RNA in a much larger proportion of sheep (72 and 67%, respectively). Animals less than 1 year of age rarely had antibodies to OvLV, although most harbored viral RNA. Twenty animals in this age group from flock 1 (Group C) were therefore studied more closely for infection. These yearling animals were tested serologically by ELISA and their peripheral blood-derived macrophages were cultured for 14 days to amplify any infection in these target cells. The macrophages were then tested by in situ hybridization, PCR, and cocultivation with susceptible target cells. The results of these tests showed that while only 10% of animals in Group C were seropositive, 70% were positive by in situ hybridization, PCR, and cocultivation. These data suggest that latent OvLV infection is common in sheep and that infection is frequently undetected by serological tests.

Anti-CD4 antibodies are associated with HIV-1 seroconversion and may be detectable before anti-HIV-1 antibodies. The Multicenter AIDS Cohort Study

We examined the sera from 14 HIV-1 seroconverters for the presence of autoantibodies against CD4. Anti-CD4 antibodies were detected in the serum of 11 of 13 HIV-1-infected persons at the time of HIV-1 seroconversion. In 6 of 14 persons from whom a serum was obtained prior to HIV-1 seroconversion, anti-CD4 antibodies were found 90 to 540 days before antibodies to HIV-1 were detectable. In comparison, anti-CD4 antibodies were present in only 7 serum samples from 62 HIV-1 seronegative individuals, including 50 from a seronegative homosexual male cohort. These results suggest that anti-CD4 antibodies are generated in response to early HIV-1 infection and possibly could be used as a marker for HIV-1 infection in some infected persons who are seronegative for HIV-1.

Activation of infectious virus from latent human immunodeficiency virus infection of monocytes in vivo

Individuals infected with HIV may be asymptomatic for years before progressing to overt AIDS. Since HIV can latently infect monocytoid cell lines, we examined whether HIV latency occurs in monocytes in vivo. Freshly isolated monocytes from asymptomatic seropositive individuals examined before and after culture were positive for HIV DNA, but not RNA, as measured by polymerase chain reaction, showing that HIV latency occurs in monocytes in vivo. Coculture of these latently infected monocytes with Con A-activated T cells from HIV-negative normal donors stimulated 90% of the patients' samples and latently infected THP-1 to produce infectious virus. Neither Con A, resting T cells, nor T cell supernatants induced virus. Plasma membranes from activated T cells stimulated HIV production, suggesting cell contact induces factor(s) in monocytes to overcome latency. Thus, monocytes in AIDS patients harbor latent HIV inducible during an immune response, leading to T cell infection and viral-induced pathology.

Perioperative haemotherapy: II. Risks and complications of blood transfusion

Major life-threatening complications following blood transfusion are rare and human error remains an important aetiological factor in many. The infectious risk from blood transfusion is predominantly hepatitis, and non-A, non-B and hepatitis C (HCV) are the most common subtypes noted. The risk of post-transfusion hepatitis (PTH) appears to be decreasing and this is attributed to both deferral of high-risk donors and more aggressive screening of donated blood. Screening for HCV is expected to decrease this risk further. The risk of HIV transmission following blood transfusion is negligibly small. There are data to suggest that perioperative blood transfusion results in suppression of the recipient's immune system. Earlier recurrence of cancer and an increased incidence of postoperative infection have been associated with perioperative blood transfusion although the evidence is not persuasive. Microaggregate blood filters are not recommended for routine blood transfusion but do have a role in the prophylaxis of non-haemolytic febrile reactions caused by platelet and granulocyte debris in the donor blood. Patients should be advised when there is likely to be a requirement for perioperative blood transfusion and informed consent for transfusion should be obtained.

AIDS and arthroscopic surgery

There are an estimated 8 to 10 million people worldwide infected with human immunodeficiency virus (HIV). The true extent of infection in the population is unknown, and many are unaware of their HIV status. Arthroscopic and arthroscopically assisted surgery is less invasive and bloody than other orthopaedic procedures, and seemingly less hazardous to surgeons. Nevertheless, the potential for exposure exists. Arthroscopic surgeons routinely experience gown, face-mask and shoe-cover saturation from the splashing of blood-tainted irrigation fluid. Glove perforations by needles, sharps, and bone fragments can occur. Bone and tissue allografts pose risks to both surgeon and patient, as HIV has been recovered from fresh, frozen and freeze-dried specimens. The process of cleaning and disinfecting arthroscopes adequately can damage these expensive devices. This article addresses the safeguards that arthroscopic surgeons should take to prevent exposure to HIV. Effective sterilizing and disinfecting techniques for arthroscopes are also discussed.

Evaluation of prognosis and survival of the HIV-infected patient

HIV disease, once considered an acute disease with a 100% mortality rate but a very short symptomatic stage, has begun to emerge as a preventable, treatable, chronic disease. Interactions between patients, dentists, and physicians are essential to gain the information necessary to provide appropriate dental care for both short-term and long-term survivors. The prognosis and survival time of the dental patient may influence treatment protocols and necessitate modified dental procedures. Certain clinical and laboratory parameters, which may be useful indicators of disease progression, need to be recognized by the dental clinician. These parameters include systemic signs, symptoms, and serologic data as well as intraoral manifestations associated with HIV disease. Although a perfect classification system for progression of HIV disease does not exist, trends among larger cohorts may enable health care providers to estimate the prognosis and survival of HIV-infected patients on an individual basis. This article presents clinical and laboratory parameters that indicate HIV disease progression. Providers who care for HIV-infected patients need to consider these parameters to establish an appropriate and flexible treatment plan based on changes in the patient's medical status.

Sequences within the feline immunodeficiency virus long terminal repeat that regulate gene expression and respond to activation by feline herpesvirus type 1

We constructed a series of deletion mutants of feline immunodeficiency virus (FIV) long terminal repeat (LTR) to identify the regions that regulate gene expression and are responsive to trans-activation of FIV LTR by feline herpes-virus type 1 (FHV-1). We demonstrated that sequences between -124 and -79, and between -21 and -32 (relative to the cap site) are essential for gene expression of FIV in Felis catus whole fetus 4 (fcwf-4) cells. Further, we demonstrated that the sequence between -63 and -23 responds to trans-activation of FIV LTR by FHV-1 in fcwf-4 cells.

Detection of HIV1 proviral DNA by PCR and hybridization with digoxigenin labelled probes

One of the main obstacles for the introduction of PCR method to identify HIV1 proviral DNA in routine diagnostic laboratories is the use of radiolabelled oligodeoxynucleotide probes. Nonradioactive labelled probes have several advantages over radioactive labelling: they are stable for over 1 year, they can be produced easily in large amounts and they are safe. Polymerase chain reaction is an efficient and simple method to produce vector free inserts to use as probes. In this paper we describe a procedure for labelling DNA probes with digoxigenin-11-dUTP using the polymerase chain reaction. This non-radioactive labelling system was applied to detect HIV proviral sequences, amplified in vitro by PCR, from peripheral blood mononuclear cells DNA of infected subjects. We found identical sensitivities and specificities for probes synthesized with the non-radioactive and radioactive labelling procedures. The digoxigenin-11-dUTP can be efficiently incorporated during amplification of a DNA fragment using the polymerase chain reaction. This labelling and detection method proved to be specific, sensible and simple enough to be used in routine diagnostic laboratories for the detection of HIV1 infected individuals.

Use of sulphonated probes for detecting human immunodeficiency virus-1 transcripts by in situ hybridization

A detailed procedure is described that allows detection of the presence of human immunodeficiency virus-1 (HIV-1) transcripts within both acetone-fixed tissues and peripheral blood mononuclear cells. This assay uses cDNA probes labelled by a non-isotopic procedure that results in the modification of cytosine residues through covalent linkage to a sulphone group. In situ hybridized probe is then detected by an alkaline phosphatase-conjugated antibody specifically directed against the sulphone hapten. This procedure is specific, rapid and safe and can be applied in the research as well as in the clinical pathology settings.

Rapid DNA fingerprinting to control for specimen errors in HIV testing by the polymerase chain reaction

Variable-number-tandem-repeats (VNTRs) are highly polymorphic and provide informative genetic markers for distinguishing between individuals. We have used PCR amplification of VNTR locus pMCT118 to identify mislabelled specimens submitted for HIV PCR testing. The method is rapid, can be applied to large numbers of samples and eliminates the need for radioactive probes. DNA samples (10 ng) are amplified for 25 cycles using fluorescence-labelled oligonucleotide primers (blue dye). An aliquot of the PCR product is then combined with an internal lane size standard (labelled with a red dye), electrophoresed through a 2% agarose gel on an automated fluorescence DNA fragment analyser and the size and quantity of the fragments determined automatically relative to the internal standard. Fifteen alleles, ranging in size from 398 tp 709 bp were readily identified in a random sampling of DNA from 63 unrelated HIV-infected patients. Fragment size was reproducible and corresponded to alleles containing from 16 to 35 repeats of a 16 bp unit. VNTR genotyping will prove useful for resolving discordant results due to specimen mix-up and ensuring that the correct samples have been analyzed.

Detection of feline immunodeficiency virus (FIV) nucleic acids in FIV-seronegative cats

A study was undertaken to determine the rate of viral transmission among naive specific-pathogen-free (SPF) cats living in close contact with feline immunodeficiency virus (FIV)-infected cats. Twenty SPF cats were housed in the same rooms with experimentally FIV-infected seropositive and virus culture-positive cats for 2 to 4 years and were monitored for the presence of FIV nucleic acids and antibodies. Only 1 of the 20 cats became seropositive and virus culture positive and developed signs of disease. Genomic DNA from bone marrow and peripheral blood mononuclear cells (PBMC) of 10 of 19 healthy-appearing seronegative cats became positive for FIV DNA by the polymerase chain reaction. Twenty-eight SPF cats housed as groups in separate quarters and never exposed to FIV-infected cats were uniformly negative for FIV DNA. FIV RNA transcripts were detected in concanavalin A-stimulated PBMC cultures from 4 of 10 FIV DNA-positive, seronegative cats by in situ hybridization. PBMC from three of four naive SPF cats acquired FIV nucleic acids after the cats were transfused with blood and bone marrow from FIV genome-positive, seronegative donors. Three of five FIV-seronegative cats housed for years with naturally FIV-infected cats in a private household were also found to harbor FIV DNA, indicating that the same phenomenon occurred in the field. These findings demonstrate that cats living in close contact with FIV-infected seropositive cats can acquire FIV nucleic acids without developing detectable levels of serum antibodies or disease.

An AIDS model with distributed incubation and variable infectiousness: applications to i.v. drug users in Latium, Italy

An AIDS model with distributed incubation and variable infectiousness is considered and simulated via a second-order numerical method. The method is applied to the HIV epidemic among IV drug users in the Latium region of Italy, using available data on the length of the incubation period before the onset of AIDS, on the infectivity of infected individuals during that period, and on the demography of drug users. The contact rate is adjusted to match the actual number of AIDS cases. The sensitivity of the model to uncertainties in the parameters is finally investigated, by performing several simulations.

Case report: fatal seronegative rickettsial infection diagnosed by the polymerase chain reaction

A previously healthy man presented with a five day history of high fever and headache, later followed by rash and the appearance of jaundice. On the second hospital day, he suddenly developed seizures, lapsed into a coma, and died. Polymerase chain reaction (PCR) amplification revealed a 434 base pairs DNA fragment common to the genome of typhus and spotted fever group rickettsiae in the patient's blood (estimated at about 1 x 10(2) organisms/ml), and to a lesser degree in the cerebrospinal fluid. However, serological tests for rickettsiae remained negative. PCR techniques may confirm the diagnosis at an early stage, even though the rickettsemia may be minimal and the patient seronegative.

New developments in serologic screening of corneal donors for HIV-1 and hepatitis B virus infections

PURPOSE

The authors evaluated different methods to serologically screen potential cadaveric corneal donors for human immunodeficiency virus type 1 (HIV-1) and hepatitis B virus (HBV) infections.

METHODS

Three commercially available enzyme-linked immunosorbent assays (ELISAs) for antibodies against HIV-1, a supplemental ELISA test for HIV antigen, and a radioimmunoassay and two ELISAs for hepatitis B surface antigen were compared using serum from cadavers with acquired immune deficiency syndrome (AIDS), cadavers with high risk factors for HIV infection, and cadavers with no known risk of HIV infection, along with respective confirmatory testing.

RESULTS

The ELISA tests for HIV antibodies from Abbott Laboratories, Electro-nucleonics, and Organon-Teknika showed sensitivities of 94.3%, 94.3%, and 97.1%, respectively, compared with the autopsy diagnosis of AIDS in 35 cadavers. The sensitivities of the HIV-1 antibody ELISAs ranged between 73% and 87% compared with positive Western blots in testing 118 sera from cadavers at high risk of HIV-infection, but not manifesting AIDS at the time of death. Supplemental ELISA testing for HIV-1 antigen, in an effort to close the seronegative window, failed to identify any HIV antigen-positive sera confirmed by neutralization that were not also positive for antibodies to HIV-1 by ELISA and Western blot. The ELISA for HBV surface antigen had an overall sensitivity of 92.9% and specificity of only 81.3% compared with radioimmunoassay in testing 409 sera. Monoclonal ELISAs for HIV-1 antigen and HBV surface antigen paradoxically had lower specificity than polyclonal ELISAs, with false positivity correlating with hemolysis and with increasing death to puncture time.

CONCLUSION

ELISA testing for antibodies against HIV-1 is relatively but not absolutely effective, should be accompanied by historical screening for risk factors, and does not appear to benefit from supplemental ELISA testing for HIV-1 antigen. ELISA testing for HBV surface antigen has lower specificity in screening cadaveric sera when compared with radioimmunoassay.

Indeterminate western blot patterns in a cohort of individuals at high risk for human immunodeficiency virus (HIV-1) exposure

Our objective was to map serial patterns of Western blot reactivity over time of a cohort of initially ELISA-negative, Western blot-indeterminate individuals from a high-risk group and to determine if these individuals were at increased risk of harboring occult HIV-1 infection. A 2-year prospective study used serial ELISA, two types of Western blot, immunologic profiles, HIV-1 culture, and analysis by polymerase chain reaction. Subjects were 20 ELISA-negative, Western blot indeterminate homosexual volunteers and 20 matched seronegative controls. Results showed that 19 of 20 study subjects completed a mean of 17.0 months of clinical and laboratory follow-up. Reactivities with p24 and/or with p55 were the two most commonly observed Western blot patterns, occurring in 70% of individuals. Specific Western blot reactivity was dependent upon the particular immunoblot preparation being used and varied considerably on a longitudinal basis. No individual pattern appeared predictive of an increased likelihood of subsequent seroconversion to HIV-1 relative to controls. By all other criteria including polymerase chain reaction analysis, samples from 17 of 19 individuals remained negative for HIV-1 at each time point. Two individuals evolved from an indeterminate to a positive Western blot and, simultaneously, from a negative to a positive polymerase chain reaction analysis, during follow-up. Our conclusions were as follows. ELISA-negative, Western blot-indeterminate individuals from a high-risk group show marked variability in immunoblot findings over time, and these patterns do not appear predictive of an increased likelihood of infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of three nonradioisotopic polymerase chain reaction-based methods for detection of human immunodeficiency virus type 1

Three nonradioisotopic polymerase chain reaction (PCR)-based detection techniques were evaluated for sensitivity and specificity in detecting human immunodeficiency virus type 1 (HIV-1) proviral DNA in peripheral blood mononuclear cells. The Roche prototype HIV-1 PCR assay, the Du Pont enzyme-linked oligonucleotide sandwich assay (ELOSA), and the Gen-Probe hybridization protection assay (HPA) were compared with a standard radioisotopic oligonucleotide solution hybridization (OSH) technique. A panel of 111 well-characterized clinical samples that included peripheral blood mononuclear cells from 48 healthy, low-risk, HIV-1 antibody-negative subjects, 24 antibody-positive subjects with stable CD4 counts of less than 200/mm3, and 39 antibody-positive subjects with stable CD4 counts of greater than 800/mm3 were studied. Each method demonstrated good specificity, ranging between 96 and 100%; those of the OSH and ELOSA (Du Pont) were 100%, those of the HPA (Gen-Probe) were 100% with one probe and 96% with the other probe, and that of the HIV-1 PCR assay (Roche) was 96%. Sensitivities ranged from 96 to 100% for the low-CD4-count group, with the OSH, the HIV-1 PCR assay (Roche), and the HPA (Gen-Probe) all attaining a sensitivity of 100%. For the high-CD4-count group, sensitivities ranged from 69 to 97%, with the OSH attaining a sensitivity of 97% and the HPA attaining sensitivities of 97% with one probe and 95% with the other probe. These data indicate that the nonradioisotopic techniques are sensitive and specific for the detection of HIV-1 proviral DNA in clinical samples.

An international collaborative study to assess a set of reference reagents for HIV-1 PCR

An international collaborative study was performed to evaluate a set of PCR reference reagents for HIV diagnosis. Twenty-six laboratories from 9 countries analysed a proficiency panel of 10 coded DNA samples using the PCR reference reagents and protocols. For comparison, these coded samples were then assessed using a laboratory's own 'in-house' reagents and methodologies. The objectives of the study were: (i) to assess inter-laboratory variation of PCR sensitivity, (ii) to evaluate the DNA 'carryover' problem and frequency of false negative results and (iii) to examine the utility of the complete set of reagents and templates to act as reference preparations for HIV PCR. Using the reference reagents, 46% of laboratories reported no false positive results in any of their assays of the negative controls. The remaining laboratories all reported a false positive result(s) in at least one assay. The overall false positive result rate for the study was 9.3%. In contrast, an overall false negative result rate of 7.4% was observed, with some laboratories recording negative results even for samples containing 10,000 molecules of target DNA. The level of absolute sensitivity may be assessed accurately only from the 12 laboratories that obtained no false positive results. All 12 laboratories detected the sample containing 10 molecules of template DNA and 9 out of the 12 laboratories detected the sample containing 1 molecule. This is in close agreement with the theoretical detection rate based on a statistical probability model for the detection of a single molecule. These characterised reference reagents were at least as sensitive as any of the 'in-house' reagents and methodologies applied, including nested PCR. The complete set of characterised reference reagents is now available for quality control assessment of HIV-1 PCR from the MRC ADP.

Comparison of immunoblots with neutralizing and complement fixing antibodies in experimental and natural cases of visna-maedi

In this study the humoral antibody response in visna-maedi virus disease in sheep during long-term infection was analyzed utilizing immunoblot assays, neutralization tests and complement fixation tests. In immunoblot assays antibodies to several virus specific protein bands were detected, both against the viral envelope glycoproteins and internal proteins of the virus. The immunoblot reaction pattern resembled that found in HIV-1 infection in humans, consistent with reported similar molecular weight of the major proteins of these two viruses. The immunoblot band pattern was compared with the pattern of complement fixing and neutralizing antibodies through the preclinical and clinical course in natural and experimental cases of visna-maedi. Of six immunoblot bands identified as virus specific, the antibody response against three gag products and the major env glycoprotein appeared early in infection, at a similar time as the complement fixing antibodies. The response against two proteins, one presumably the transmembrane protein and the other possibly a gag precursor, was delayed.

Social intervention against AIDS among injecting drug users

Many drug injectors continue to engage in behaviors that lead them to become infected with HIV in spite of a wide variety of public health programs. In addition, many persons have begun to inject drugs in spite of knowing the risks of AIDS. The inadequacy of current efforts to prevent these behaviors suggests that additional forms of intervention should be attempted. We suggest that social interventions be tried to complement current programs (almost all of which have an individual focus). Evidence that social factors such as peer pressure and the social relations of race affect risk behavior is presented. Social interventions that are discussed include organizing drug injectors against AIDS in ways analogous to those in which gays organized against the epidemic, and finding ways to change large-scale social relationships that predispose people to inject drugs.

Evidence of an in vitro association between human immunodeficiency virus antigen P24 and Epstein-Barr virus DNA

To investigate the association between human immunodeficiency virus (HIV) and Epstein-Barr virus (EBV), simultaneous determinations of HIV antigen (HIV Ag) p24 and EBV DNA were performed in lymphocyte culture supernatants from 63 individuals at risk of HIV infection. In vitro data, together with HIV immune status results, were subjected to a statistical analysis. HIV infection was identified in 49 patients (78%); of these, in vitro EBV DNA was found in 44 individuals (90%), while in only 3 of the 14 non-infected ones (21%). Statistical analysis demonstrated a close relationship between evidence of HIV infection and in vitro detection of EBV DNA (87.3% concordant with 95% confidence interval: 76.5%-94.5%). Furthermore, a strong dependence was revealed between the presence of EBV DNA and HIV Ag in culture (p less than 0.00001). These results indicate the existence of in vitro viral interactions, with likely in vivo implications in the pathogenesis and evolution of HIV infection.