Henry Okonta - Academia.edu (original) (raw)

Papers by Henry Okonta

Research paper thumbnail of Vertical Transmission of a Murine Retrovirus, ts1

Viral Immunology, 2004

Mechanism of maternal retroviral transmission remains an unsolved problem. The current investigat... more Mechanism of maternal retroviral transmission remains an unsolved problem. The current investigation is a part of our ongoing research on vertical transmission of MoMuLV-TB ts1 in BALB/c mice. A total of 270 adult mice and 165 fetuses were used. Forty-four experimental mice were injected with 0.1 mL of 4.0 ϫ 10 6 ffu/mL of ts1 virus at 72 h after birth; 24 controls were injected with DMEM. Almost half of the females went through two rounds of pregnancies. In the first round, 135 experimental and 57 control pups were produced. Forty-three experimental and 20 control pups were followed until they developed clinical symptoms. The second round of pregnancy produced a total of 46 mid-gestational and 119 full-term fetuses. PCR, and light and electron microscopy were performed to evaluate viral transmission. Overall, 99% vertical transmission occurred in pups of infected mothers. Twelve percent of mid-gestational and 39% full-term fetuses were PCR positive. We have established that, if mothers are infected with ts1 virus at 72 h after birth, then nearly 100% vertical transmission occurs, via in utero, intrapartum, or breast milk. Thirty-nine percent transmission occurred in utero alone. This is an excellent model to study the transplacental and post-gestational transmission of retroviruses, such as ts1.

Research paper thumbnail of Murine Retroviral Model of Perinatal Viral Transmission

Background: ts-1 is a temperature sensitive mutant of the wild type Moloney Murine Leukemia Virus... more Background: ts-1 is a temperature sensitive mutant of the wild type Moloney Murine Leukemia Virus (Mo MuLV) which differs from wild type by 11 amino acids. Infection of susceptible mouse strains with ts-1 virus result in a well-documented syndrome of neuro-degeneration and immunodeficiency with splenic and thymic atrophy. We have developed and characterized an animal model of perinatal transmission of this retrovirus including novel observations not seen in the model of ts-1 for neurodegeneration. Methods: BALB/C mice inoculated IP 72 hours after birth with 0.1 ml of 4x106 ffu/ml ts-1 were mated at maturity. The viral transmission to fetuses and pups was evaluated. Histology and clinical features of perinatal disease were compared to those of non-perinatally acquired ts-1 infection and wild type Mo MuLV infection. Results: In utero transmission rates were as follows: 12% (2/17 fetuses) day 10 gestation, 39% (37/94 fetuses) at day 19 of gestation, 78.3% (36/46 pups) immediately after...

Research paper thumbnail of Determination of Phenotype and Mrna Expression in a Retrovirus Induced Murine Lymphoma Model

Background: Approximately 95% of HIV-1-associated lymphomas are considered to be of B-cell origin... more Background: Approximately 95% of HIV-1-associated lymphomas are considered to be of B-cell origin. The vast majority of these tumors are high grade B-cell lymphoma. The objective of the current study is to determine: 1) the phenotype of lymphoma associated with temperature sensitive Moloney Murine Leukemia Virus (Mo-MuLV-ts1) and 2) the alteration in mRNA expression of these lymphomas. Methods: A total of 117 BALB/c pups were divided into 4 groups: 24 (group #1) from infected mothers were allowed to suckle from their infected biological mother; 38 control pups (group #2) from non-infected mother suckled from surrogate infected mothers; 46 pups of infected mothers (group #3), suckled from control surrogate mothers and 9 control pups (group #4) suckled from their non infected biological mother. Splenic tissues were used for immunohistochemistry and qRT-PCR. Antibodies to CD3 and CD79a were used to identify the T-and B-cell lymphomas respectively. mRNA expression levels for each of 28 ...

Research paper thumbnail of Determination of Common Integration Site of a Maternally Inherited Retroviral Genome in Murine Model

Background: We have developed a mouse model to study the maternally inherited virus induced lymph... more Background: We have developed a mouse model to study the maternally inherited virus induced lymphoma. We have observed, 9 of 26 pups of Molony Murine Leukemia temperature sensitive virus (MoMuLv-ts-1) infected mothers developed lymphoma, while 17 of their infected littermates did not. None of the control pups of uninfected mothers developed lymphoma.Our model is unique because it is T-cell derived and similar to human AIDS related lymphomas while most murine leukemia virus are known to cause B-cell lymphoma. The goal of the present study was to examine the common integration sites (CIS) of the viral genome into the infected host genome, causing lymphoma. Methods: Genomic DNA from lymph nodes of mice with lymphoma was digested with BamH1, purified and ligated using T4 ligase for I-PCR. PCR was performed using each set of inverse primers designed from MoMuLV-ts1 sequence for the 5’end and the 3’ end products of BamH1 digest. Secondary PCR reaction was performed using primary PCR produ...

Research paper thumbnail of Retroviral gene insertion in breast milk mediated lymphomagenesis

Research paper thumbnail of A Small Animal Model for Mother-to-Fetus Transmission of ts1, a Murine Retrovirus

Viral Immunology, 2003

Infection with a murine retrovirus, MoMuLV-TB, ts1 in BALB/c mice has been established as a small... more Infection with a murine retrovirus, MoMuLV-TB, ts1 in BALB/c mice has been established as a small animal model for retroviral neurodegenerative disease as shown with infections such as HIV. However, mother-to-pup transmission has never been demonstrated in this model. The current investigation examines vertical transmission of ts1 in this mouse model. A total of 15 females were used to produce 59 pups (16 were used for control, and 43 were used as experimental animals). For experiment 1, 24 5-day-old mice were injected with [0.2 mL of 2.0 x 10(6) ffu/mL ts1] virus. For experiment 2, 19 48-h-old mice were injected with [0.1 mL of 4 x 10(6) ffu/mL ts1] virus. Control groups were injected with DMEM only. PCR and electron microscopy were performed to determine the presence of virus. All mice from experiment 1 injected with ts1 showed viral infection, and retained 100% reproductive capacity. Three out of 102 pups produced by these infected females were infected with ts1. Nine percent of the pups from experiment 2 injected with ts1 retained normal reproductive capacity, and two out of eight (25%) pups had viral infection. Vertical transmission of this unique retrovirus occurs and is dependent, in part, on the timing of maternal infection.

Research paper thumbnail of Vertical Transmission of a Murine Retrovirus, ts1

Viral Immunology, 2004

Mechanism of maternal retroviral transmission remains an unsolved problem. The current investigat... more Mechanism of maternal retroviral transmission remains an unsolved problem. The current investigation is a part of our ongoing research on vertical transmission of MoMuLV-TB ts1 in BALB/c mice. A total of 270 adult mice and 165 fetuses were used. Forty-four experimental mice were injected with 0.1 mL of 4.0 x 10(6) ffu/mL of ts1 virus at 72 h after birth; 24 controls were injected with DMEM. Almost half of the females went through two rounds of pregnancies. In the first round, 135 experimental and 57 control pups were produced. Forty-three experimental and 20 control pups were followed until they developed clinical symptoms. The second round of pregnancy produced a total of 46 mid-gestational and 119 full-term fetuses. PCR, and light and electron microscopy were performed to evaluate viral transmission. Overall, 99% vertical transmission occurred in pups of infected mothers. Twelve percent of mid-gestational and 39% full-term fetuses were PCR positive. We have established that, if mothers are infected with ts1 virus at 72 h after birth, then nearly 100% vertical transmission occurs, via in utero, intrapartum, or breast milk. Thirty-nine percent transmission occurred in utero alone. This is an excellent model to study the transplacental and post-gestational transmission of retroviruses, such as ts1.

Research paper thumbnail of Retrovirus-induced lymphomagenesis: a correlation between disease pathogenesis and flow cytometric analysis

Journal of General Virology, 2012

Perinatal infection with a temperature-sensitive mutant (ts-1) of Moloney murine leukemia virus (... more Perinatal infection with a temperature-sensitive mutant (ts-1) of Moloney murine leukemia virus (MoMuLV) results in massive splenomegaly and thymomegaly in mice and development of lymphoma in .55 % of infected pups. Previous flow cytometry studies showed a decrease in CD4 + cells in perinatally infected pups, but cell population changes in infected animals with lymphoma compared with infected animals without lymphoma has not yet been reported. In the current study, BALB/c mice were infected with ts-1 through breast milk transmission and observed until development of clinical signs and symptoms of lymphoma and/or symptomatic ts-1 infection. Flow cytometry studies were performed on blood, spleen and thymus samples and correlated with gross morphology and histological changes, resulting from the development of lymphoma. Infected animals with lymphoma had significant decreases in CD4 + and CD8 + cell counts in blood and spleen compared with controls. The spleens of infected animals without lymphoma showed a decrease in CD4 + and CD8 + cell counts, but this was not significant compared with controls. In the thymus, CD4 + and CD8 + cell counts also decreased, but this was not significant in infected animals with and without lymphoma compared with controls. Markers of myeloid cell dysfunction increased in the thymus of animals with infection with and without lymphoma compared with controls. Thus, immunosuppression and CD4 + /CD8 + cell decreases in the spleen and thymus are associated with malignant transformation and development of lymphoma in this animal model.

Research paper thumbnail of Transmission of Moloney murine leukemia virus (ts-1) by breast milk

Journal of General Virology, 2006

A murine model has been developed to study maternal transmission of the temperature-sensitive Mol... more A murine model has been developed to study maternal transmission of the temperature-sensitive Moloney murine leukemia virus (ts-1). The goal of this study was to confirm early and late mother-to-offspring transmission of the virus and demonstrate transmission via breast milk. A series of six experiments was performed using six groups of BALB/c mice. Group 1 consisted of pups born to ts-1-infected mothers removed at birth to suckle from surrogate uninfected mothers. Groups 2 and 5 consisted of pups born to ts-1-infected mothers that suckled from ts-1-infected mothers (surrogate and biological). Group 3 consisted of non-infected pups removed at birth to suckle from ts-1-infected mothers. Groups 4 and 6 consisted of non-infected pups suckled from non-infected mothers. The combined in utero, intrapartum and breast-milk infection rate was 100 % to the offspring (groups 2 and 5). The in utero to early post-partum group (group 1) had an infection rate of 78 %. Breast milk alone (group 3) resulted in a 97 % infection rate. Control groups (groups 4 and 6) had a 0 % infection rate. The relative frequency of maternal CD4 + cells in peripheral blood mononuclear cells was consistently lower in infected mothers, whilst offspring did not show a significant decrease in CD4 + frequency. Pups infected via breast milk had a lower CD4 + frequency (group 3) than those infected by the uterine and/or intrapartum route (group 1). Breast milk from ts-1-infected mothers appears to be highly infectious for neonatal BALB/c mice.

Research paper thumbnail of Vertical Transmission of a Murine Retrovirus, ts1

Viral Immunology, 2004

Mechanism of maternal retroviral transmission remains an unsolved problem. The current investigat... more Mechanism of maternal retroviral transmission remains an unsolved problem. The current investigation is a part of our ongoing research on vertical transmission of MoMuLV-TB ts1 in BALB/c mice. A total of 270 adult mice and 165 fetuses were used. Forty-four experimental mice were injected with 0.1 mL of 4.0 ϫ 10 6 ffu/mL of ts1 virus at 72 h after birth; 24 controls were injected with DMEM. Almost half of the females went through two rounds of pregnancies. In the first round, 135 experimental and 57 control pups were produced. Forty-three experimental and 20 control pups were followed until they developed clinical symptoms. The second round of pregnancy produced a total of 46 mid-gestational and 119 full-term fetuses. PCR, and light and electron microscopy were performed to evaluate viral transmission. Overall, 99% vertical transmission occurred in pups of infected mothers. Twelve percent of mid-gestational and 39% full-term fetuses were PCR positive. We have established that, if mothers are infected with ts1 virus at 72 h after birth, then nearly 100% vertical transmission occurs, via in utero, intrapartum, or breast milk. Thirty-nine percent transmission occurred in utero alone. This is an excellent model to study the transplacental and post-gestational transmission of retroviruses, such as ts1.

Research paper thumbnail of Murine Retroviral Model of Perinatal Viral Transmission

Background: ts-1 is a temperature sensitive mutant of the wild type Moloney Murine Leukemia Virus... more Background: ts-1 is a temperature sensitive mutant of the wild type Moloney Murine Leukemia Virus (Mo MuLV) which differs from wild type by 11 amino acids. Infection of susceptible mouse strains with ts-1 virus result in a well-documented syndrome of neuro-degeneration and immunodeficiency with splenic and thymic atrophy. We have developed and characterized an animal model of perinatal transmission of this retrovirus including novel observations not seen in the model of ts-1 for neurodegeneration. Methods: BALB/C mice inoculated IP 72 hours after birth with 0.1 ml of 4x106 ffu/ml ts-1 were mated at maturity. The viral transmission to fetuses and pups was evaluated. Histology and clinical features of perinatal disease were compared to those of non-perinatally acquired ts-1 infection and wild type Mo MuLV infection. Results: In utero transmission rates were as follows: 12% (2/17 fetuses) day 10 gestation, 39% (37/94 fetuses) at day 19 of gestation, 78.3% (36/46 pups) immediately after...

Research paper thumbnail of Determination of Phenotype and Mrna Expression in a Retrovirus Induced Murine Lymphoma Model

Background: Approximately 95% of HIV-1-associated lymphomas are considered to be of B-cell origin... more Background: Approximately 95% of HIV-1-associated lymphomas are considered to be of B-cell origin. The vast majority of these tumors are high grade B-cell lymphoma. The objective of the current study is to determine: 1) the phenotype of lymphoma associated with temperature sensitive Moloney Murine Leukemia Virus (Mo-MuLV-ts1) and 2) the alteration in mRNA expression of these lymphomas. Methods: A total of 117 BALB/c pups were divided into 4 groups: 24 (group #1) from infected mothers were allowed to suckle from their infected biological mother; 38 control pups (group #2) from non-infected mother suckled from surrogate infected mothers; 46 pups of infected mothers (group #3), suckled from control surrogate mothers and 9 control pups (group #4) suckled from their non infected biological mother. Splenic tissues were used for immunohistochemistry and qRT-PCR. Antibodies to CD3 and CD79a were used to identify the T-and B-cell lymphomas respectively. mRNA expression levels for each of 28 ...

Research paper thumbnail of Determination of Common Integration Site of a Maternally Inherited Retroviral Genome in Murine Model

Background: We have developed a mouse model to study the maternally inherited virus induced lymph... more Background: We have developed a mouse model to study the maternally inherited virus induced lymphoma. We have observed, 9 of 26 pups of Molony Murine Leukemia temperature sensitive virus (MoMuLv-ts-1) infected mothers developed lymphoma, while 17 of their infected littermates did not. None of the control pups of uninfected mothers developed lymphoma.Our model is unique because it is T-cell derived and similar to human AIDS related lymphomas while most murine leukemia virus are known to cause B-cell lymphoma. The goal of the present study was to examine the common integration sites (CIS) of the viral genome into the infected host genome, causing lymphoma. Methods: Genomic DNA from lymph nodes of mice with lymphoma was digested with BamH1, purified and ligated using T4 ligase for I-PCR. PCR was performed using each set of inverse primers designed from MoMuLV-ts1 sequence for the 5’end and the 3’ end products of BamH1 digest. Secondary PCR reaction was performed using primary PCR produ...

Research paper thumbnail of Retroviral gene insertion in breast milk mediated lymphomagenesis

Research paper thumbnail of A Small Animal Model for Mother-to-Fetus Transmission of ts1, a Murine Retrovirus

Viral Immunology, 2003

Infection with a murine retrovirus, MoMuLV-TB, ts1 in BALB/c mice has been established as a small... more Infection with a murine retrovirus, MoMuLV-TB, ts1 in BALB/c mice has been established as a small animal model for retroviral neurodegenerative disease as shown with infections such as HIV. However, mother-to-pup transmission has never been demonstrated in this model. The current investigation examines vertical transmission of ts1 in this mouse model. A total of 15 females were used to produce 59 pups (16 were used for control, and 43 were used as experimental animals). For experiment 1, 24 5-day-old mice were injected with [0.2 mL of 2.0 x 10(6) ffu/mL ts1] virus. For experiment 2, 19 48-h-old mice were injected with [0.1 mL of 4 x 10(6) ffu/mL ts1] virus. Control groups were injected with DMEM only. PCR and electron microscopy were performed to determine the presence of virus. All mice from experiment 1 injected with ts1 showed viral infection, and retained 100% reproductive capacity. Three out of 102 pups produced by these infected females were infected with ts1. Nine percent of the pups from experiment 2 injected with ts1 retained normal reproductive capacity, and two out of eight (25%) pups had viral infection. Vertical transmission of this unique retrovirus occurs and is dependent, in part, on the timing of maternal infection.

Research paper thumbnail of Vertical Transmission of a Murine Retrovirus, ts1

Viral Immunology, 2004

Mechanism of maternal retroviral transmission remains an unsolved problem. The current investigat... more Mechanism of maternal retroviral transmission remains an unsolved problem. The current investigation is a part of our ongoing research on vertical transmission of MoMuLV-TB ts1 in BALB/c mice. A total of 270 adult mice and 165 fetuses were used. Forty-four experimental mice were injected with 0.1 mL of 4.0 x 10(6) ffu/mL of ts1 virus at 72 h after birth; 24 controls were injected with DMEM. Almost half of the females went through two rounds of pregnancies. In the first round, 135 experimental and 57 control pups were produced. Forty-three experimental and 20 control pups were followed until they developed clinical symptoms. The second round of pregnancy produced a total of 46 mid-gestational and 119 full-term fetuses. PCR, and light and electron microscopy were performed to evaluate viral transmission. Overall, 99% vertical transmission occurred in pups of infected mothers. Twelve percent of mid-gestational and 39% full-term fetuses were PCR positive. We have established that, if mothers are infected with ts1 virus at 72 h after birth, then nearly 100% vertical transmission occurs, via in utero, intrapartum, or breast milk. Thirty-nine percent transmission occurred in utero alone. This is an excellent model to study the transplacental and post-gestational transmission of retroviruses, such as ts1.

Research paper thumbnail of Retrovirus-induced lymphomagenesis: a correlation between disease pathogenesis and flow cytometric analysis

Journal of General Virology, 2012

Perinatal infection with a temperature-sensitive mutant (ts-1) of Moloney murine leukemia virus (... more Perinatal infection with a temperature-sensitive mutant (ts-1) of Moloney murine leukemia virus (MoMuLV) results in massive splenomegaly and thymomegaly in mice and development of lymphoma in .55 % of infected pups. Previous flow cytometry studies showed a decrease in CD4 + cells in perinatally infected pups, but cell population changes in infected animals with lymphoma compared with infected animals without lymphoma has not yet been reported. In the current study, BALB/c mice were infected with ts-1 through breast milk transmission and observed until development of clinical signs and symptoms of lymphoma and/or symptomatic ts-1 infection. Flow cytometry studies were performed on blood, spleen and thymus samples and correlated with gross morphology and histological changes, resulting from the development of lymphoma. Infected animals with lymphoma had significant decreases in CD4 + and CD8 + cell counts in blood and spleen compared with controls. The spleens of infected animals without lymphoma showed a decrease in CD4 + and CD8 + cell counts, but this was not significant compared with controls. In the thymus, CD4 + and CD8 + cell counts also decreased, but this was not significant in infected animals with and without lymphoma compared with controls. Markers of myeloid cell dysfunction increased in the thymus of animals with infection with and without lymphoma compared with controls. Thus, immunosuppression and CD4 + /CD8 + cell decreases in the spleen and thymus are associated with malignant transformation and development of lymphoma in this animal model.

Research paper thumbnail of Transmission of Moloney murine leukemia virus (ts-1) by breast milk

Journal of General Virology, 2006

A murine model has been developed to study maternal transmission of the temperature-sensitive Mol... more A murine model has been developed to study maternal transmission of the temperature-sensitive Moloney murine leukemia virus (ts-1). The goal of this study was to confirm early and late mother-to-offspring transmission of the virus and demonstrate transmission via breast milk. A series of six experiments was performed using six groups of BALB/c mice. Group 1 consisted of pups born to ts-1-infected mothers removed at birth to suckle from surrogate uninfected mothers. Groups 2 and 5 consisted of pups born to ts-1-infected mothers that suckled from ts-1-infected mothers (surrogate and biological). Group 3 consisted of non-infected pups removed at birth to suckle from ts-1-infected mothers. Groups 4 and 6 consisted of non-infected pups suckled from non-infected mothers. The combined in utero, intrapartum and breast-milk infection rate was 100 % to the offspring (groups 2 and 5). The in utero to early post-partum group (group 1) had an infection rate of 78 %. Breast milk alone (group 3) resulted in a 97 % infection rate. Control groups (groups 4 and 6) had a 0 % infection rate. The relative frequency of maternal CD4 + cells in peripheral blood mononuclear cells was consistently lower in infected mothers, whilst offspring did not show a significant decrease in CD4 + frequency. Pups infected via breast milk had a lower CD4 + frequency (group 3) than those infected by the uterine and/or intrapartum route (group 1). Breast milk from ts-1-infected mothers appears to be highly infectious for neonatal BALB/c mice.