Biomedical subjects

G V Hillyer

Publications and source records attributed to G V Hillyer.

At least 19 recordsLinked to original sources

PubMed2000

Vaccination of mice against schistosoma bovis with a recombinant fatty acid binding protein from Fasciola hepatica.

Two strains of mice (NMRI and C57/BL) were each immunized with a 15kDa recombinant Fasciola hepatica fatty acid binding protein (FABP) (Fh15) and challenged percutaneously with Schistosoma bovis cercariae. C57/BL mice immunized with Fh15 had significant reductions in S. bovis worm burden recoveries (72% reductions over controls). When using NMRI mice, Fh15 in Freund's adjuvant failed to induce significant protection against S. bovis. In C57/BL mice, only antibodies to the IgG2a isotype increased after the second immunization and remained high through 8 weeks of S. bovis infection. This is the first time that a heterologous recombinant molecule from F. hepatica has been used in vaccination against S. bovis, obtaining a significant reduction in the number of worms in C57/BL mice.

Animals↗

PubMed1999

A fatty acid binding protein from Fasciola hepatica induced protection in C57/BL mice from challenge infection with Schistosoma bovis.

Three strains of mice (NMRI, C57/BL, BALB/c) were each immunized with a 12 kDa purified, native Fasciola hepatica fatty acid binding protein (Fh12) and challenged percutaneously with Schistosoma bovis cercariae. C57/BL mice immunized with Fh12 had significant reductions in S. bovis worm burden recoveries (96 and 87% reductions over controls in two separate experiments). When using NMRI or BALB/c mice, Fh12 alone or in Freund's adjuvant failed to induce significant protection against S. bovis. In C57/BL mice vaccinated against Fh 12, antibodies to the IgG2a isotype, but not to the IgG1 isotype, increased by 2 weeks after the second immunization and remained high through 8 weeks of S. bovis infection. Antibodies to S. bovis increased after 4 weeks of infection. Regarding cytokine production by spleen mononuclear cells, C57/BL mice vaccinated with Fh12 in adjuvant, and having the highest protective response against challenge infection with S. bovis, had an increase of IFN-gamma production with Concanavalin A but no increase of IL-4 in similarly stimulated cells. These results suggest that the protection obtained in this group of mice is mediated by a Th1 immune response.

Animals↗

PubMed1999

Age-specific decrease in seroprevalence of schistosomiasis in Puerto Rico.

In our previous work, we reported the first systematic, island-wide, serologic survey for schistosomiasis in Puerto Rico in 40 years. In that study, approximately 3,000 serum samples from the 76 municipalities comprising the island of Puerto Rico were tested for the detection of antibodies to S. mansoni microsomal antigens by the Falcon assay screening test-enzyme-linked immunosorbent assay (FAST-ELISA) and those positive were confirmed by an enzyme-linked immunoelectrotransfer blot (EITB). The highest EITB positivity was found in 17 municipalities, which comprised 48% of all seropositive samples. An additional finding was that 10% of the 215 EITB-positive samples were from individuals 25 years or younger and were for the most part of residents from the high seroprevalence areas. Thus, for this study we focused on 766 individuals 25 years of age or younger (45.5% males and 54.4% females), two-thirds of which were from 10 municipalities with the highest EITB seropositivity, and one-third from the 10 municipalities with the lowest EITB seropositivity found in our previous study. Of all samples, the results showed an overall FAST-ELISA positivity of 11.6%, with males similar to females (12.6 versus 10.7%, respectively). Confirmation by EITB was only 1.8%, with a males three-fold higher than females (3% versus 0.7%). When seropositivity was measured by age in five-year increments, a clear age-specific decrease in seropositivity was observed. Thus, by FAST-ELISA, 16.7% of the 21-25-year-old age group was positive, decreasing to 14.6%, 9.9%, 7.9%, and 9.3% in the 16-20-, 11-15-, 6-10-, and 1-5-year-old age groups, respectively. Confirmatory EITB showed even more impressive results: 4.7%, 2.6%, 1.2%, 0.7%, and 0% in the same age brackets. With regard to the high prevalence municipalities, only four of 10 (11 of 228 = 4.8%) had confirmatory EITB-positive samples and most were from municipalities of the Rio Grande de Loiza River basin and tributaries. The male to female positivity ratio was 4:1. Of the low prevalence municipalities, only single positive cases (by EITB) were found in three disperse municipalities. These results support the concept that there has been little transmission of S. mansoni in Puerto Rico during the first half of the 1990s and confirms anecdotal comments of local physicians who have seen virtually no new infections during the past three years. This makes the documentation of eradication of schistosomiasis from Puerto Rico feasible, a goal that should be set as being before the 100th anniversary of its discovery on the island by Isaac Gonzalez-Martinez in 1904.

Adolescent↗

PubMed1999

Seroepidemiology of schistosomiasis in Puerto Rico: evidence for vanishing endemicity.

The current study summarizes our findings of anti-schistosome egg antibody by the circumoval precipitin test for two different populations in Puerto Rico. One group, exclusively males more than 40 years of age and from all municipalities on the island, was from the Veterans Administration Hospital for the period 1988-1997. The second group resided southeast of San Juan, around the municipality of Caguas and adjacent municipalities east of Caguas, was of both sexes and mostly until 1997 of undetermined ages for the period 1993-1997. Results reveal a yearly decrease in testing requests from the Veterans Administration Hospital from 148 in 1988 and 1989 with 16% positive to three in 1996 through 1998 with none positive. This decrease in testing requests was because of a decrease of suspicion of schistosomiasis in this group. The other patient population from the Caguas region showed a gradual but continuous decrease in seropositive individuals from 21% in 1993 to 12% in 1996, with precipitous decrease to 5% in 1997 and only 1% in 1998. Moreover, there were four patients from which at least two serum samples were obtained one or two years apart and tested. In each instance the more recently obtained sample had lower antibody reactions than the first as reflected in lower percentages of positive egg reactors. The fact that they were treated with praziquantel after the first testing also suggests that the infected population was being eliminated through chemotherapy. These combined results suggest the elimination of infections with Schistosoma mansoni in the traditionally high prevalence regions east of San Juan in the absence of any proactive control efforts in Puerto Rico. Because of the rapid urbanizing of Puerto Rico, the one identifiable control effort is economic development and well being.

Adult↗

PubMed1998

A comparison of peripheral blood coculture versus 18- or 24-month serology in the diagnosis of human immunodeficiency virus infection in the offspring of infected mothers. Women and Infants Transmission Study.

The Women and Infants Transmission Study (WITS) has established virologic definitions of human immunodeficiency virus (HIV)-infected and uninfected children that have been widely used but never formally compared with serologic definitions of infection. Data from the offspring of HIV-infected women in the WITS with frequent HIV cultures during the first year of life and with HIV serology at 18 and/or 24 months of age were analyzed. Seventy-seven infants were HIV-infected and 430 uninfected by both virologic and serologic criteria. Thirteen were virologically infected (> or = 2 positive cultures) but either seronegative or serologically indeterminate. All but 1 of these had clinical HIV disease at the time of analysis. In this pediatric cohort, children defined as infected by virologic criteria often (13/90) had negative or indeterminate serology despite symptoms of HIV disease. Results suggest that serology at 18-24 months has high specificity but poor sensitivity. It should not be considered the reference standard in identifying HIV infection in perinatally exposed children.

Blotting, Western↗

PubMed1998

Absolute copy number and relative change in determinations of human immunodeficiency virus type 1 RNA in plasma: effect of an external standard on kit comparisons.

Use of a common set of human immunodeficiency virus type 1 (HIV-1) RNA standards eliminated differences among absolute HIV-1 RNA copy number estimates made with three commercially available assays. The relative changes in the viral RNA levels determined by the commercial assays were similar and were unaffected by the use of a common set of standards.

Female↗

PubMed1997

Elevated CD8+DR+ lymphocytes in HIV-exposed infants with early positive HIV cultures: a possible early marker of intrauterine transmission. Women and Infants Transmission Study Group.

The associations among timing of maternal-fetal human immunodeficiency virus (HIV) transmission, infant age at first positive HIV culture, and CD8+ lymphocyte activation were examined for 74 perinatally infected infants. Nineteen of the infected infants had positive HIV cultures at < or =7 days of life, and 55 had negative HIV cultures at < or =7 days but were positive later. Of the infants with early positive HIV-1 cultures, 15 of the 17 tested with DNA polymerase chain reaction methods had concordant results. The percentage of CD8+ and HLA-DR+ lymphocytes (CD8+DR+%) during the first week of life was significantly higher in infants with early compared with late positive cultures (median CD8+DR+% of 5.0% versus 2.0%, p = 0.0006). The CD8+DR+% was similar between uninfected infants and infants with late positive cultures during the first week of life (median 2%) but increased in infants with late positive cultures to 6% by 1 month. The CD4+% during the first 6 months of life was not different between infants with early or with late positive cultures, but infants with the highest CD8+DR+% at < or =7 days of life had significantly lower CD4+% at < or =7 days and at 1, 2, and 4 months of age. These data show that early CD8+ lymphocyte activation is associated with early positive HIV cultures and lower CD4+ percentages during early infancy and are consistent with the hypothesis that early positive cultures positivity may indicate in utero HIV infection.

Biomarkers↗

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↗