Biomedical subjects

M Saifuddin

Publications and source records attributed to M Saifuddin.

31 records · Page 2Linked to original sources

PubMed1996

Susceptibility of HIV-1 plasma virus to complement-mediated lysis. Evidence for a role in clearance of virus in vivo.

This study was undertaken to directly assess the susceptibility of HIV-1 plasma virus to C-mediated lysis. Plasma from HIV-infected individuals was collected and ultracentrifuged over 20% sucrose to isolate virions from plasma components including anticoagulants, which inhibit C activity. Treatment with C alone in the absence of exogenously added Ab caused lysis of virus from all patients (n = 18) (range 14 to 86%). This lysis occurred via the classical C pathway and was not due to cross-reactive Abs in the C source. Protein A bound a fraction of isolated plasma virus and this binding was blocked by purified human Ig suggesting that anti-HIV Abs bound to plasma virus could be responsible for inducing C activation. A portion of virus bound to CR2 on cells in the absence of exogenously added C indicating that virus activated C in vivo. C levels from six of six patients were determined to be sufficient to lead to lysis of virus in vivo. Since plasma virus appeared more sensitive to C than primary isolates, isolated virus was evaluated for the presence of C control proteins. While primary isolate virions contained CD46, CD55, and CD59, only CD59 was detected on plasma virus. The results of this study strongly suggest that C is activated by a portion of plasma virus in vivo due to the binding of Ab. The resultant opsonization plus subsequent lysis may be important routes of clearance and destruction of plasma virus in infected persons.

Antigens, CD↗

PubMed1996

Identification of a DNA segment in ferret Aleutian disease virus similar to a hypervariable capsid region of mink Aleutian disease parvovirus.

A 401bp DNA fragment of ferret Aleutian disease virus (ADV) was amplified using PCR primers spanning a hypervariable region of mink ADV capsid sequence. The amplified fragment was 88-89% homologous to the same region of previously known sequence of three different strains of mink ADV, however, as low as 54% homology was observed when compared with a 39bp segment known as hypervariable region. Within the predicted 13 amino acid hypervariable region, the ferret ADV sequence differed at 6 positions from the wild type mink Utah1 strain. Three amino acids Gln289, Glu293 and Thr295 in this region were common to the pathogenic ferret ADV, mink Utah1 and ADVK strains, but differed from the cell culture adapted nonpathogenic mink strain ADVG suggesting that these three conserved residues may have some functional significance.

Aleutian Mink Disease Virus↗

PubMed1995

Host cell-derived complement control proteins CD55 and CD59 are incorporated into the virions of two unrelated enveloped viruses. Human T cell leukemia/lymphoma virus type I (HTLV-I) and human cytomegalovirus (HCMV).

The current study was undertaken to determine whether the human T cell leukemia/lymphoma oncovirus type I (HTLV-I) and the herpesvirus human cytomegalovirus (HCM) incorporate host cell-derived C regulatory proteins. Our experiments showed that both CD59 and CD55 were associated with the external membrane of HTLV-I derived from MT2 cells, since virus could be captured by mAbs to these proteins, and antisera to CD55 and CD59 induced C-mediated lysis of HTLV-I virions. Additionally, both CD55 and CD59 were detected by immunoblot analysis of purified HTLV-I. Purified HCMV produced in human foreskin fibroblasts (HFF) also contained both CD55 and CD59, as detected by immunoblot analysis. However, treatment with anti-CD55, but not anti-CD59, reduced the HCMV infectious titer in the presence of C. Additional studies determined whether HTLV-I-associated CD55 and CD59 participated in the resistance of the virus to C-mediated lysis. Treatment of virus with phosphatidylinositol-specific phospholipase C (PI-PLC), which removes glycosylphosphatidylinositol-anchored CD55 and CD59, increased the sensitivity of HTLV-I to C-mediated destruction in the presence of anti-HTLV-I Abs. Reconstitution of PI-PLC-treated virus with purified CD55 and CD59 restored resistance to C. These experiments show that HTLV-I and HCMV acquire C control proteins from host cells. Together with our previous experiments showing that both CD55 and CD59 are present on HIV-1, these studies demonstrate a mechanism by which a variety of enveloped viruses may acquire resistance to C-mediated destruction.

CD55 Antigens↗

PubMed1995

Role of virion-associated glycosylphosphatidylinositol-linked proteins CD55 and CD59 in complement resistance of cell line-derived and primary isolates of HIV-1.

This study investigates whether cell-derived glycosylphosphatidylinositol-linked complement control proteins CD55 and CD59 can be incorporated into HIV-1 virions and contribute to complement resistance. Virus was prepared by transfection of cell lines with pNL4-3, and primary isolates of HIV-1 were derived from patients' PBMCs. Virus was tested for sensitivity to complement-mediated virolysis in the presence of anti-gp160 antibody. Viral preparations from JY33 cells, which lack CD55 and CD59, were highly sensitive to complement. HIV-1 preparations from H9 and U937 cells, which express low levels of CD55 and CD59, had intermediate to high sensitivity while other cell line-derived viruses and primary isolates of HIV-1 were resistant to complement-mediated virolysis. Although the primary isolates were not lysed, they activated complement as measured by binding to a complement receptor positive cell line. While the primary isolates were resistant to lysis in the presence of HIV-specific antibody, antibody to CD59 induced lysis. Likewise, antibody to CD55 and CD59 induced lysis of cell line-derived virus. Western blot analysis of purified virus showed bands corresponding to CD55 and CD59. Phosphatidylinositol-specific phospholipase C treatment of either cell line-derived or primary isolates of HIV-1 increased sensitivity to complement while incubation of sensitive virus with purified CD55 and CD59 increased resistance to complement. These results show that CD55 and CD59 are incorporated into HIV-1 particles and function to protect virions from complement-mediated destruction, and they are the first report of host cell proteins functioning in protection of HIV-1 from immune effector mechanisms.

Antigens, CD↗

PubMed1995

HTLV-I activates complement leading to increased binding to complement receptor-positive cells.

This investigation was performed to determine whether HTLV-I can activate complement, since previous studies show that complement activation by some viruses, including HIV-1, can enhance binding to, and infection of complement receptor-positive (CR+) cells. Complement treatment increased binding of HTLV-I to CR+ HPB-ALL cells by approximately 5-fold. In contrast, increased binding was not observed with H9 cells, which lack CR. Heat inactivation or EDTA treatment of complement blocked this increased binding while EGTA treatment only partially blocked binding. Anti-CR2 antibody significantly blocked binding of complement-treated HTLV-I to HPB-ALL cells. Since previous studies showed that HIV-1 could activate complement, activation of complement by this virus was compared with HTLV-I. It was observed that binding of HTLV-I to HPB-ALL cells was enhanced by highly dilute complement (> or = 1:810) while HIV-1 required much higher concentrations of complement (> or = 1:30), indicating that HTLV-I is a much stronger complement activator. Treatment with complement transiently increased the ability of HTLV-I to infect CR+ cell lines as judged by provirus formation (4- to 8-fold increase) and p24 production (5- to 10-fold increase). In contrast, complement treatment did not increase infection of CR- cells. In conclusion this study shows that HTLV-I activates complement leading to increased binding to, and transiently increased infection of, CR+ cells. This complement-mediated increased binding of HTLV-I may dramatically affect viral trafficking and immunological reactivity of virus in vivo.

Antibodies, Blocking↗

PubMed1994

Host cell components affect the sensitivity of HIV type 1 to complement-mediated virolysis.

An infection-competent, full-length HIV-1 clone (pNL4-3) was expressed in seven human cell lines and in peripheral blood mononuclear cells in order to assess the contribution of host cell components toward interaction of free virus with the complement system. HIV-1 expressed in the H9 cell line, which is frequently used for in vitro infection, was relatively susceptible to complement-mediated virolysis in the presence of both HIV antibody-positive patient serum and an anti-V3 monoclonal antibody. Expression of complement receptors 1, 2, and 3, complement control proteins membrane inhibitor of reactive lysis (MIRL, CD59) and decay-accelerating factor (DAF, CD55), and HLA-DR was assessed on host cells. There was an inverse relationship between the sensitivity of virus to complement and the amount of expression of MIRL and DAF on cells. HIV derived from the JY cell line and the mutant JY33 cell line, which is deficient in expression of phosphatidylinositol (PI)-linked proteins including MIRL and DAF, were also evaluated for complement-mediated virolysis. Virus expressed in the mutant cell line was more sensitive to antibody-independent as well as antibody-dependent complement-mediated virolysis than virus expressed in the wild-type cells. Direct demonstration of the presence of MIRL and DAF on the viral surface was obtained by showing that anti-MIRL or anti-DAF antibody induced complement-mediated virolysis. These experiments show that the host cell type can substantially influence the susceptibility of HIV to complement-mediated virolysis and suggest that PI-linked complement control proteins play an important role in this resistance.

Acquired Immunodeficiency Syndrome↗

PubMed1993

Evaluation of isolator caging systems for protection of mice against challenge with mouse hepatitis virus.

Two isolator caging systems were evaluated against challenge with MHV-Y, an enterotropic strain of mouse hepatitis virus. The systems were similar in that they both used an identical shoebox cage equipped with a polycarbonate filter top incorporating a Reemay filter. They differed in that one system supplied HEPA-filtered air through a grommet in the filter lid so that the cage was pressurized slightly. A rack holding 60 cages (30 front and back) was utilized. Thirty cages without filter tops housed one mouse each that had been infected orally with 19,000 ID50 of MHV-Y and an uninfected cagemate. The remaining 30 cages, each housing 2 uninfected mice were divided into 3 groups of 10 cages. Group I cages (controls) had no filter top; Group II cages were equipped with filter tops; and Group III were equipped with filter tops and intracage HEPA-filtered air. The cages housing uninfected mice were interspersed between, above, below and behind cages housing infected mice. The uninfected mice were maintained in contact with the MHV-Y infected mice for 8 weeks. Transmission of MHV-Y was determined serologically by indirect ELISA. All mice housed within the Group I cages (control) seroconverted to MHV, while only 4 mice (2 cages) seroconverted in Group II, and no mice seroconverted in Group III.

Animals↗

PubMed1992

Effects of fowl adenovirus infection on the immune system of chickens.

A virulent strain of serotype 8 fowl adenovirus (FAV) was isolated from an outbreak of inclusion body hepatitis (IBH) in broiler flocks. Post-mortem changes included characteristic liver lesions with intranuclear inclusion bodies in the hepatocytes and severe lymphocytic depletion in the bursa, thymus and spleen. The packed cell volume was reduced by 50 per cent or more and varying amounts of cell depletion were observed in the bone marrow. Typical IBH was reproduced in specific pathogen-free chickens inoculated orally with the FAV isolated from the natural infection. There was severe depletion of lymphocytes in the bursa, thymus and spleen of the experimentally infected birds and FAV antigens were detected by ELISA and immunocytochemical staining in various lymphoid tissues. Humoral antibody responses against sheep red blood cells, detected by the haemagglutination test, were decreased in the chickens infected with FAV. These findings suggest that the damage caused by replication of this virulent strain of FAV in lymphoid tissues compromises the immunological capabilities of infected chickens.

Adenoviridae Infections↗

PubMed1991

Pathogenesis of an acute viral hepatitis: inclusion body hepatitis in the chicken.

The pathogenesis of inclusion body hepatitis was studied following the oral administration of a serotype 8 strain of avian adenovirus into 2-day-old specific pathogen free chickens. Viral antigens were detected in tissues at various times post inoculation (pi) by enzyme-linked immunosorbent assay and by immunocytochemistry. Viral antigens were detected in intestinal epithelium from 12h to 13 days pi and in the plasma fraction of blood by 24 h pi. A biphasic, cell-free viremia with peaks at 2 and 7 days pi was recorded. Antigens were first detected in the liver from 2 days and reached peak levels at 6 days pi. The second peak of viral antigens in blood plasma was probably due to release of virus from damaged hepatic cells. Initially, viral antigens in the liver were restricted to cells lining the sinusoids but increasing involvement of hepatocytes occurred with time. Small amounts of viral antigens were detected in other tissues. Following the appearance of neutralizing antibodies in serum from 7 days pi, the levels of viral antigens in all tissues decreased and were undetectable by 15 days pi. This viral hepatitis of chickens is possibly a useful model for other viral infections where a cell-free viremic phase is important for spread of virus from primary sites to target organs, such as the liver.

Adenoviridae Infections↗

PubMed1991

Development of an immunocytochemical procedure to detect adenoviral antigens in chicken tissues.

An immunocytochemical technique utilizing an avidin-biotin peroxidase complex was developed to detect viral antigens in various tissues following oral administration of a locally isolated serotype 8 avian adenovirus (AAV) in specific pathogen-free (SPF) chickens. A strong color reaction was obtained with tissues from infected birds that contained a minimal amount of AAV antigens as determined by an indirect enzyme-linked immunosorbent assay. No reaction was detected in sections of tissues obtained from SPF chickens, and the reactivity with infected tissues could be removed by prior absorption of the primary antibody with purified AAV. A group-specific antigen common to the 12 serotypes of AAV was demonstrated by this technique. Because of the high sensitivity and broad-spectrum reactivity, this technique could be useful for studying the pathogenesis and laboratory diagnosis of inclusion body hepatitis caused by several serotypes of AAV.

Adenoviridae Infections↗

PubMed1990

Protection conferred by vaccination with Blacksburg and Komarov strains of Newcastle disease virus against Newcastle disease in Bangladesh.

An evaluation was undertaken of the efficacy of vaccination of day-old chicks with the Blacksburg (B1) strain of Newcastle disease virus (NDV) followed at various times by vaccination with the Komarov (K) strain. Antibody was detected by the haemagglutination inhibition (HAI) test one week after vaccination with B1 and titres peaked at three weeks and had declined to undetectable levels by nine weeks. After subsequent vaccination with K strain at five, seven or eight weeks of age levels of HAI antibody (titre 80 to 640) were detected after three weeks. Birds vaccinated at seven weeks were tested for antibody and resistance to challenge beyond 19 weeks of age. In this group the HAI titres remained constant (80 to 640) up to 32 weeks of age and then steadily declined to 10 to 20 at 44 weeks of age. A linear relationship between HAI titre and virus neutralising index (VNI) was demonstrated with a range of selected sera. Only birds with an HAI titre of 80 or greater resisted artificial challenge. It is recommended that, following B1 vaccination at day-old and K vaccination at seven weeks old, revaccination with K strain should be performed at intervals of not more than seven months.

Animals↗

PubMedDate not supplied

Development of an enzyme-linked immunosorbent assay to detect and quantify adenovirus in chicken tissues.

An indirect enzyme-linked immunosorbent assay (ELISA) was developed to detect and quantify avian adenovirus (AAV) in various chicken tissues, including blood. A positive ELISA absorbance value was obtained with suspensions of infected liver tissue that contained less than 100 mean tissue-culture infective doses per gram. A positive correlation was observed between the absorbance values and titer of infectious virus in infected liver tissue. A group-specific antigen common to the 12 serotypes of AAV tested was demonstrated by this ELISA. Because of the high sensitivity and broad-spectrum reactivity, this ELISA could be useful for the study of AAV pathogenesis, for laboratory diagnosis of inclusion body hepatitis irrespective of the serotype of AAV involved, and for screening commercial and specific-pathogen-free flocks for the presence of AAV.

Adenoviridae↗

PubMedDate not supplied

A primary epidemic of inclusion body hepatitis in broilers.

Inclusion body hepatitis (IBH) was diagnosed in 15 broiler flocks supplied by one breeder in the South Island of New Zealand. The affected flocks suffered mortality up to 30%. Malaise and slightly increased mortality were noticed by growers from about day 12 post-hatch; mortality peaked in the fourth week, and, in most flocks, declined to normally accepted levels from day 33 on. Gross signs seen at necropsy usually included bone-marrow aplasia, atrophy of the bursa of Fabricius and the thymus, and swollen hemorrhagic livers with focal necrosis. Jaundice was seen in many surviving birds. In some flocks, there was also proventricular hemorrhage, mild tracheitis, and airsacculitis. Downgrading and condemnation rates were increased in all flocks. Eosinophilic intranuclear inclusion bodies were seen in hepatocytes of some affected birds. An adenovirus was isolated from a number of cases investigated. The disease in broilers was preceded by production drops associated with feed refusal and increased mortality in the breeder stock.

Animals↗