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Biomedical subjects

G V Hillyer

Publications and source records attributed to G V Hillyer.

At least 37 records · Page 2Linked to original sources
PubMed1997

Fasciola hepatica: vaccination of rabbits with native and recombinant antigens related to fatty acid binding proteins.

The current study was designed to compare the immunogenic and immunoprophylactic properties of native (nFh12) and recombinant (rFh15) antigens from Fasciola hepatica in rabbits infected with the fluke. Levels of specific anti-nFh12 and anti-rFh15 antibodies were significantly higher in the rabbits vaccinated twice compared with non-vaccinated infection controls. A reduction of 40% in worm burdens was found in rabbits immunized with nFh12 and infected 4 weeks after the second immunization. The recombinant vaccine induced lesser levels of protection than the native one, suggesting that both molecules may have slight differences either in immunogenicity or in their configuration. Further biochemical studies are required to define these differences. The mean length of flukes recovered was always smaller in all vaccinated rabbits. In addition, infected control rabbits had higher gamma glutamil transferase (GGT) levels than immunized rabbits. Lastly, gross anatomic observation always showed fewer liver lesions in all vaccinated rabbits than in controls. This finding clearly supports the possibility of vaccination regimes in fasciolosis.

Animals↗
PubMed1997

Increased vertical transmission of human immunodeficiency virus from hepatitis C virus-coinfected mothers. Women and Infants Transmission Study.

To determine if hepatitis C virus (HCV) infection affects vertical transmission of human immunodeficiency virus (HIV), 487 HIV-infected pregnant women in the prospective, multicenter, Women and Infants Transmission Study had HCV antibody (anti-HCV by second-generation ELISA) and HCV RNA (by quantitative polymerase chain reaction) measured in peripartum maternal plasma; 161 (33%) were anti-HCV-positive. HIV vertical transmission occurred from 42 HCV-infected mothers (26.1%) versus 53 HCV-uninfected mothers (16.3%; odds radio [OR], 1.82; P = .01). In a logistic regression model that included maternal drug use, a potential confounder, HCV infection was marginally associated with perinatal HIV transmission (OR, 1.64; P = .05), whereas drug use was not. Women who transmitted HIV had higher levels of HCV RNA (median, 721,254 copies/mL) than those who did not (337,561 copies/mL; P = .01). Maternal HCV infection is associated with increased HIV vertical transmission. Further studies are needed to ascertain if HCV directly affects perinatal HIV transmission or is a marker for another factor, such as maternal drug use.

Adult↗
PubMed1997

Maternal immunologic and virologic risk factors for infant human immunodeficiency virus type 1 infection: findings from the Women and Infants Transmission Study.

Maternal virus load of human immunodeficiency virus 1 (HIV-1) and maternal immunity are both associated with risk of an infected infant. The interrelationship of these two variables in describing that risk was assessed in a multisite study of 475 mother-infant pairs. Infant infection was associated with low CD4 cell percentage, high CD8, CD8/CD38, and CD8/DR cell percentages, persistently positive HIV-1 cultures, and high HIV-1 titer (P < .001, .001, .005, .006, .001, and .013, respectively). The association of CD4 cell percentage and increased CD8, CD8/CD38, and CD8/DR cell percentages with transmission was restricted to the 42% of women whose HIV-1 cultures were not persistently positive (all P < .001). Women with at least 1 negative culture and high CD4 cell percentage or low CD8 cell percentage were at very low risk (0-4%) of transmitting HIV-1, while those with always positive cultures transmitted at a high rate (18%-27%), regardless of immune status.

Adolescent↗
PubMed1997

Geographic clustering and seroprevalence of schistosomiasis in Puerto Rico (1995).

A systematic, island-wide survey for schistosomiasis in Puerto Rico has not been conducted for more than 40 years. In 1974, a thorough survey of Boqueron de Las Piedras, a small community, showed a prevalence of 40%. No additional information on prevalence in Puerto Rico has been obtained during the ensuing 21 years. Concern for the public health of residents and visitors prompted the formation of the Bilharzia Commission in 1994 and the systematic serosurvey reported herein. Two thousand nine hundred fifty-five plasma samples from healthy donors were obtained randomly from the Red Cross in March and April 1995. Sex, resident municipalities, and age of the donors were recorded. The donors were from all but three of 79 municipalities in Puerto Rico. No sample was available from the three out island municipalities of Mona, Vieques, and Culebra. Male donors (n = 2,027) outnumbered females (n = 928) by more than 2:1, ages ranged from nine to 76 years with most (85.3%) between 19 and 51 years of age. All samples were tested with the Falcon assay screening test:enzyme-linked immunosorbent assay (FAST:ELISA) with microsomal antigens of Schistosoma mansoni. All FAST:ELISA+ samples were confirmed by enzyme-linked immunoelectrotransfer blot (EITB). Our data showed that 15.4% were FAST:ELISA+, and 10.6% were confirmed by EITB; 13.5% of the males and 4.1% of the females were EITB+. If we exclude those municipalities with fewer than five samples, the prevalence of EITB+ ranged from 0% to 38.5%, with the highest seroprevalence rates (21.1-38.5%) concentrated in 17 municipalities, which accounted for 48% of all seropositive samples. These 17 municipalities, however, contain only 18% of the total population of Puerto Rico. Two areas of high seroprevalence rates center around Jayuya (38.5%) and Naguabo (36.4%). The previously surveyed area of Boqueron is located in Las Piedras (35.3%), adjacent to Naguabo. In addition, we found 10% (21) of our total 215 donors less than 25 years of age to be EITB+ and all but two are residents of the high prevalence districts. These data strongly support the contention that schistosomiasis has been transmitted in a focal fashion during the past approximately 20 years.

Adolescent↗
PubMed1997

Longitudinal studies on maternal HIV-1 variants by biological phenotyping, sequence analysis and viral load.

In this study, the HIV-1 variant viruses from ten pregnant women and their infants were isolated and characterized longitudinally in order to determine the role that viral envelope (gp120-V3 loop) gene variation and viral tropism play in vertical transmission. Biological phenotyping of each HIV variant was accomplished by growth in MT-2, and macrophages from healthy and non-HIV-infected donors. Genetic characterization of the variants was accomplished by DNA sequence analysis. All the women enrolled in this study received ZDV therapy. Virus was cultured from eight out of ten env V3-PCR positive mothers. HIV-1 isolates were all non-syncitium inducing variants. None of the mothers were found to transmit HIV, as determined by DNA PCR and quantitative co-cultures on their infants which were seronegative for HIV-1 through one year after birth. Viral cultures from infant blood samples were negative and infants were all healthy. However, nested env V3-PCR detected proviral DNA in five out of ten infants. In contrast, conventional gag-PCR was negative in the same five infants. Sequences of the five maternal-infant pairs were different, suggesting unique infant HIV-1 variants. The three highest maternal viral load values corresponded to infants that were env V3-PCR positive. These results suggest that HIV-1 particles are transmitted from ZDV-treated mothers to infants. Infant follow up is recommended to determine if HIV-1 has been inhibited by the immune system of the infants.

Adult↗
PubMed1996

Herd evaluation by enzyme-linked immunosorbent assay for the determination of Fasciola hepatica infection in sheep and cattle from the Altiplano of Bolivia.

A study was designed to determine by ELISA the seroprevalence of fasciolosis both in sheep (29 herds totaling 184 sheep), in samples collected in 1988, and in cattle (41 herds totaling 299 animals, samples collected in 1988; 34 herds totaling 147 animals, samples collected in 1989) in the same area of Corapata in which a seroprevalence survey had been done in humans. The results show high seropositivity in sheep (89%) and lower seropositivity in cattle (58% in 1988, and 57% in 1989). The seroprevalence in cattle in 1988 was essentially identical to that detected in 1989. Faecal examinations were also done in the 1988 sheep and 1989 cattle. Results of the study showed that of the 184 sheep examined, 22 were positive for F. hepatica eggs, while 163 were positive by serology. All of the 22 sheep which were positive parasitologically were also positive serologically for a sensitivity of 100%. On the other hand, of 147 cattle tested, 38 were positive parasitologically while 84 were positive serologically. Of the 38 positives for F. hepatica eggs, 31 were positive by serology (sensitivity 82%).

Animals↗
PubMed1996

Early detection of human immunodeficiency virus on dried blood spot specimens: sensitivity across serial specimens. Women and Infants Transmission Study Group.

OBJECTIVE: To evaluate the use of dried blood spot (DBS) specimens and the early diagnostic value of the polymerase chain reaction (PCR) for detection of the human immunodeficiency virus (HIV) in DBS specimens collected at predefined age intervals from a large cohort of U.S. infants at risk of congenital or perinatal HIV infection. DESIGN: We assayed available DBS specimens (n = 272) obtained during the first 4 months of life from 144 infants (41 infected, 103 uninfected) born to HIV-infected mothers enrolled in the Women and Infants Transmission Study. The DBS PCR results were compared with infant HIV infection status, PCR on liquid blood, and viral culture results. Analyses also included sensitivity and specificity of assay as related to the age of the infant when the specimen was obtained. RESULTS: The DBS specimen PCR results were concordant with results from liquid blood specimens and with results from viral culture. The DBS PCR was highly specific for all age groups. Sensitivity in detecting HIV infection status rapidly increased during the first month of life, from 19% (5/26) by 1 week to 96% (25/26) by 1 month of age. Specimens obtained on the day of birth or the next day were the least likely to have detectable HIV DNA. CONCLUSIONS: The PCR assay of DBS specimens is a reliable tool for the early diagnosis of HIV infection and has important advantage over that of liquid blood DNA PCR and viral culture. These advantages include a lower volume of blood required for testing, increased safety, and ease of storage or transport of specimens. Thus DBS PCR is a useful test for clinical and epidemiologic tracking of infants at risk of HIV infection.

Blood Preservation↗
PubMed1996

Diagnosis of infection with human immunodeficiency virus type 1 by a DNA polymerase chain reaction assay among infants enrolled in the Women and Infants' Transmission Study.

Early diagnosis of infection with human immunodeficiency virus type 1 (HIV- 1) in young infants is essential to decisions on their medical and social care. Whereas studies have suggested that polymerase chain reaction (PCR) is a sensitive and timely method of diagnosing HIV infection in children, these evaluations have been limited by the number of specimens studied. Recently, Roche Molecular Systems developed a complete HIV-1 DNA PCR testing kit (from specimen preparation to detection). In this study, use of this PCR test kit was evaluated for the detection of HIV infection in infants of seropositive mothers who were enrolled in the longitudinal, multicenter Women and Infants' Transmission Study. A total of 1209 blood specimens from 483 infants were tested and analyzed. The overall sensitivity and specificity of a single PCR test in determining HIV infection status in infants more than 1 but less than 36 months of age were 95% and 97%, respectively. For infected infants 1 to 6 months of age the sensitivity of the DNA-PCR test was 90% to 100%. In a direct comparison with coculture, the Roche DNA-PCR test was significantly more sensitive than coculture in the detection of HIV-1 in infected infants and was equivalent to coculture for the diagnosis of HIV in infants when a standardized algorithm was used to define infection status.

Algorithms↗
PubMed1995

Detection of excretory-secretory circulating antigens in sheep infected with Fasciola hepatica and with Schistosoma mansoni and F. hepatica.

Two groups of sheep were exposed to Fasciola hepatica and Schistosoma mansoni/F. hepatica infections, respectively, to determine the time of appearance of F. hepatica circulating excretory-secretory (FhES) antigens. Five sheep were infected orally with 400 F. hepatica metacercariae. Five additional sheep were infected first percutaneously with 5000 S. mansoni cercariae, and 10 weeks later orally with 400 F. hepatica metacercariae. Antigen detection was performed in the two groups by a double antibody microELISA. In the group infected with F. hepatica, circulating FhES antigens were detected in all five animals. In the group infected first with S. mansoni none of the sera had positive optical density values for FhES antigens throughout the 10 week period following infection. After F. hepatica challenge, FhES antigens were detected in all animals. Thus, sheep infected with S. mansoni did not develop detectable F. hepatica circulating antigens during the 10 week period following Schistosoma infection. Anti-FhES antibodies were detected by FAST-ELISA, and all animals infected with F. hepatica were positive. In the group infected with S. mansoni, cross-reactive antibodies to F. hepatica were detected by 4-6 weeks post infection. All sheep with double infections showed high antibody levels by 2 weeks after infection with F. hepatica.

Animals↗
PubMed1995

An outbreak of acute fascioliasis among Aymara Indians in the Bolivian Altiplano.

Fasciola hepatica is a common and important parasite of sheep, cattle, and other ruminants. In May 1991, 30 persons with possible acute fascioliasis were identified by health care providers at a district hospital in the Bolivian Altiplano, and two deaths were associated with this illness. A cross-sectional survey of a random sample of 30 (20%) of the 148 households in the community and a case-control study were performed to determine the extent of the outbreak and the vehicle of transmission. Ninety-one members from 23 of the 30 selected families participated in the cross-sectional survey. Twenty-one of the 91 members met the case definition for acute fascioliasis (illness since 16 February 1991 that was characterized by fever and abdominal pain plus serum IgG antibodies to F. hepatica), and 38 (49%) of 78 members had serum IgG antibodies to F. hepatica. If this rate is extrapolated to the entire community, an estimated 116 individuals (23% of 504) would have acute fascioliasis and 247 individuals (49% of 504) would have evidence of current or previous infection. Case-control analysis indicated that the only factor associated with illness was eating kjosco (an aquatic plant) while tending animals in the fields; 27 (52%) of the 52 case-patients vs. 9 (14%) of the 66 controls ate kjosco (OR = 6.84; 95% CI = 2.60, 18.44). The cause of the two deaths attributed to fascioliasis could not be firmly established. Fascioliasis is a significant human health problem and is highly endemic in the Aymara Indian community in the Bolivian Altiplano. Efforts to prevent fascioliasis should include educating people to avoid eating uncooked aquatic plants such as kjosco.

Acute Disease↗
PubMed1995

Seroreversion in human immunodeficiency virus-exposed but uninfected infants.

The goal of this study was to describe seroreversion (SR) in a cohort of human immunodeficiency virus-exposed but uninfected infants. Groups of patients who seroreverted very early or late were examined for salient clinical and immunologic characteristics of the mother or infant. The mean time (+/- s.d.) to seroreversion by enzyme-linked immunoabsorbent assay (ELISA) was 50.1 +/- 14.8 weeks, or 11.6 months (n = 84); the range of times to antibody loss by ELISA was 17.9 to 82.0 weeks. The mean time to seroreversion by Western blot was 68.3 +/- 12.6 weeks, or 15.8 months (n = 51), with a range of 44.9 to 94.1 weeks. Initial anti-human immunodeficiency virus titer as measured by cord blood ELISA optical density (OD) was found to relate significantly to mean time to seroreversion. No relationship to time to seroreversion was demonstrated for gestational age, maternal or neonatal serum immunoglobulin concentrations, maternal CD4 cell counts, maternal alcohol consumption, infantile diarrhea or failure to thrive. The lengthy time to seroreversion seen here demonstrates the 1994 revised Centers for Disease Control and Prevention definition of human immunodeficiency virus infection (based on seropositivity by both ELISA and confirmatory tests persisting beyond 18 months of age) to be accurate in our population. We recommend Western blot testing be used as confirmation for positive ELISAs only after 18 months of age.

AIDS Serodiagnosis↗
PubMed1994

Identification of genes that encode Fasciola-specific arc 2 antigens.

Previous studies have shown that serum from humans with fascioliasis had precipitating antibodies that identified a line of precipitation as specific for Fasciola. This Fasciola-specific band was designated arc 2. The specificity of a Fasciola-specific anti-arc 2 antiserum, evaluated by Western blot analysis, reveals a mosaic of antigens with molecular weights in the range of 10-43 kD. In the current study, the antibodies reacting with a subset of antigens in the 10-21-kD range were eluted from nitrocellulose and used to probe an F. hepatica cDNA library. Four clones were purified and amplified by the polymerase chain reaction. The DNA hybridizations among these clones revealed different groups of clones derived from different mRNAs. The finding of multiple genes supports the observation that F. hepatica arc 2 is a mosaic of antigens. The studies show that molecular cloning technology can be used to identify potential genes, each of which encode distinct antigens that may be used for the specific immunodiagnosis of fascioliasis.

Animals↗
PubMed1993

Sequence analysis of a Fasciola hepatica glutathione S-transferase cDNA clone.

A lambda gt11 Fasciola hepatica cDNA library was previously constructed from poly(A)+ RNA extracted from adult worms. A cDNA encoding F. hepatica glutathione S-transferase (FhGST) (GenBank Accession Number M93434) was cloned by screening the library with a rabbit anti-FhGST antiserum. The FhGSTs are suspected to be early developmentally expressed-proteins that act as potent immunogens and may be useful as candidate vaccines against the parasite. The cDNA was sequenced and contains 627 translated bases encoding a 24,211-Dalton polypeptide with 209 amino acids and an isoelectric point (pI) of 5.324. This polypeptide has significant homology with 26-kD GSTs from Schistosoma mansoni (57.42%) and S. japonicum (57.14%). In addition, we have identified the predicted T cell epitopes in the FhGST protein molecule.

Amino Acid Sequence↗
PubMed1993

Evaluation of an ELISA for the diagnosis of human infection with S. haematobium.

ShSEA prepared from eggs collected from urine samples of infected humans and SmSEA prepared from eggs collected from infected hamsters were tested in an ELISA against 226 human sera classified in four groups, 30 normal controls, 82 S. mansoni infected, 64 S. haematobium infected and 50 with concurrent infection with both species. ELISA proved to be efficient diagnostic test for schistosomiasis giving 98-100% sensitivity, but low species specificity, 23-28%. However, the mean absorbance value of S. haematobium infection sera was significantly higher with homologous than heterologous antigens which indicate the presence of S. haematobium species-specific antigens.

Adolescent↗
PubMed1992

Fasciola hepatica: host responders and nonresponders to parasite glutathione S-transferase.

Fasciola hepatica glutathione S-transferase (FhGST) was isolated from adult worms by glutathione agarose affinity chromatography. SDS-PAGE shows three proteins of M(r) ranging from 29-27.8 kDa. Western immunoblot analyses using SDS-PAGE separated adult worm extracts and probed with a rabbit anti-FhGST antiserum reveal two bands in the same M(r) range. Mice and rabbits immunized with purified FhGST develop copious amounts of anti-FhGST antibodies. Moreover, antisera to F. hepatica adult worms and excretion-secretion products also react with FhGST. Cross-reactivity with schistosomes is evidenced in the reactivity with FhGST of anti-Schistosoma mansoni adult worm antisera and, to a lesser extent, antisera to S. mansoni-soluble egg antigens. The time of appearance of anti-FhGST antibodies in different species of animals infected with F. hepatica was determined. Sheep and a New Zealand white rabbit developed anti-FhGST antibodies detectable by ELISA as early as 2 weeks postexposure with F. hepatica. However, neither mice nor calves infected with F. hepatica developed antibodies to FhGST through the 5-10 weeks of infection tested. But mice infected with S. mansoni developed anti-FhGST cross-reacting antibodies by 6 weeks of infection. Calves immunized with a Fasciola/Schistosoma cross-reactive, cross-protective antigen complex in which a 12,000-kDa protein (Fh12) has been shown to contain immunoprophylactic activity, also developed antibodies to FhGST. Since FhGST is a novel potential vaccine, its protection-inducing capability in a multivalent vaccine combined with Fh12 clearly warrants study. In summary, it appears that hosts with fascioliasis are either responders to FhGST (rabbits, sheep) or nonresponders (mice, cattle), offering interesting models for studying the immune response.

Animals↗
PubMed1992

Fasciola hepatica: molecular cloning, nucleotide sequence, and expression of a gene encoding a polypeptide homologous to a Schistosoma mansoni fatty acid-binding protein.

Immunization of mice with an antigenic polypeptide from Fasciola hepatica adult worms and having an apparent molecular mass of 12,000 Da (Fh12) has been shown to reduce the worm burden from challenge infection with Schistosoma mansoni by more than 50%. Moreover, mice infected with S. mansoni develop antibodies to Fh12 after 5-6 weeks of infection, indicating that this Fasciola-derived antigen is a cross-reactive, cross-protective protein. A lambda gt11 F. hepatica cDNA library was constructed from poly(A)+ RNA extracted from adult worms. A cDNA encoding a cross-reactive polypeptide (Fh15) was cloned by screening the F. hepatica lambda gt11 library with a monospecific, polyclonal rabbit antiserum against pure, native Fh12. The cDNA was sequenced and the predicted amino acid sequence revealed an open reading frame encoding a 132-amino-acid protein with a predicted molecular weight of 14,700 Da. This protein has significant homology to a 14-kDa S. mansoni fatty acid-binding protein. Comparison of the protective-inducing activity of recombinant Fh15 with that of purified Fh12 against schistosomes and Fasciola is warranted.

Amino Acid Sequence↗
PubMed1992

The purification and characterization of a cysteine protease of Fasciola gigantica adult worms.

A 26-28 kDa protease was isolated from Fasciola gigantica adult worms by a two-stage purification process of column chromatography in a Sephacryl S-200 column and affinity chromatography in an L-phenylalanine-agarose column. This protease is a cysteine (thiol) proteinase with an optimum pH of 4.5 and is not inhibited by anti F. gigantica immunoglobulin G. The enzyme was inhibited by protease inhibitors known to inhibit cysteine proteases but not by metallo-, aspartate or serine protease inhibitors. The effect of several protease inhibitors and anti-F, gigantica IgG was also assessed on the total proteolytic activity of F. gigantica. There appears to be a preponderance of cysteine protease activity in F. gigantica and there was a significant inhibition of total proteolytic activity by anti-F. gigantica IgG.

Animals↗