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Latent foamy and simian retroviruses in healthy African green monkeys used in biomedical research
RESEARCH LETTERS
We proposed thiamine deficiency causing Wernicke’s encephalopathy as an explanation for his symptoms. He was treated with 100 mg of thiamine as an intravenous bolus. Subsequently, 100 mg thiamine with 1 g of folate and multivitamins were administered in an intravenous infusion over 24 h. Within 12 h of starting treatment, improvement was noted. Within 48 h he was able to abduct each eye 90 degrees past the midline, and there was improvement in tandem walking. The encephalopathy was slower to resolve than the other neurological symptoms. Appetite response to thiamine supplementation was difficult to assess because of a strong behavioural component to the food refusal, but by 1 week he accepted a full diet. 1 month later, he showed nearcomplete recovery of all neurological functions. Thiamine deficiency is a potential risk in any chronically malnourished individual. Wernicke’s disease has been reported before in children who were fed thiamine-deficient infant formulae,1 and also in paediatric oncology patients who had extended periods of emesis and limited food intake related to chemotherapy.2–4 In general, this is a rare condition in children. Acute intravenous glucose loads may precipitate the clinical symptoms of Wernicke’s disease, by depleting thiamine stores. 1
2
3
4
Seear MD, Norman MG. Two cases of Wenicke’s encephalopathy in children: an under diagnosed complication of poor nutrition. Ann Neurol 1988; 24 (1): 85–87. Bruck W, Christen JH, Latomek H, Hanefeld F, Friede RL, Wernicke’s encephalopathy in a child with acute lymphoblastic leukemia treated with polychemotherapy. Clin Neuropath 1991; 10 (3): 134–36. Miyajima Y, Fukuda M, Kojima S, Matsuyama T, Shylaja N, Aso K. Wernicke’s encephalopathy in a child with acute lymphoblastic leukemia. Am J Ped Hematol-Oncol 1993; 15 (3): 331–34. Pihko H, Saarinen U, Paetu A. Wernicke encephalopathy—a preventable cause of death: report of two children with malignant disease. Pediat Neurol 1989; 5 (4): 237–42.
Departments of Neurology (A L Gropmans) and Psychiatry, Children’s National Medical Center, Washington, DC, and Department of Neurology, Georgetown University Hospital, Washington, DC 20010, USA
Latent foamy and simian retroviruses in healthy African green monkeys used in biomedical research V A Morozov, S Lagaye
For several decades, African green monkeys (AGMs) and macaques have been used as sources of cells and blood for vaccine trials. The health of animals is assessed visually and by serology for infections. However, even seronegative animals, especially from the wild, could be infected with latent viruses and retroviruses, so their biological material may be a source of infections. During the 1950s and 1960s primary kidney-cell cultures of wild AGMs and macaques were used worldwide for polio vaccine preparation. In some countries wild AGMs and macaques are still used. Foamy retroviruses (FVs) have been isolated from Old-World primates and are thought to be latent in their natural hosts.1 Simian type-D retroviruses (SRV) have been detected in Asian primates and are prevalent in colonyborn macaques. On the basis of limited immunological data, African primates and AGMs in particular were considered to be free of SRV infection. However, SRV has been isolated from Ethiopian baboons.2 SRVs induce severe immunodeficiency, especially in animals kept in primate research centres. FV and SRV are easily transmitted in vivo,
THE LANCET • Vol 351 • June 6, 1998
FV and SRV-3 sequences PCR amplified from the DNAs of healthy AGMs (A) Detection of FV int sequences by “nested” PCR and (B) detection of SRV-3 env sequences by PCR-Southern hybridisation with DIGlabelled env probe. Tracks 1–13=DNA from AGMs, +=DNA from FV (A) and SRV-3 (B) infected human cells (positive controls), ⫺=DNA from uninfected human cells (negative controls), M⫺=DIG-labelled DNA markers VI (Boehringer-Mannheim, Germany). Primers and conditions for “nested” PCR amplification of int FV specific sequences, and primers and probes for SRV-3 gag and env sequences amplification and detection were as described.4,5 Each 100 L reaction mixture contained 200 ng of DNA sample, 100 ng of each primer, 200 nmol/L of each deoxynucleotide, 1·5 mmol/L MgCI2 and 3 U of Taq polymerase (PerkinElmer, USA). For “nested” PCR, 5 L from the first PCR reaction was used. Positions and sizes of amplimers are given on the right.
but infection of man is still questioned.3–5 We surveyed FVs and SRV-3 markers in DNA and serum samples from 13 wild (SV40-negative) and apparently healthy AGMs from Kenya used for biomedical research. Samples were examined first by PCR with -globin primers. Screening for FVs sequences was by nested PCR with universal int-specific primers (provided by M Schweizer).4 Primers for SRV-3 amplification were as described:5 gag (positions 510–530, 1129–1109), and env (positions 6878–6898, 7459–7439). SRV-3 amplimers were Southern hybridised to digoxigenin (DIG)-labelled probes.5 FV sequences were found in seven of 13 AGMs (figure a, tracks 1, 2, 5–7, 10, 11). One animal contained FV and both gag (not shown) and env SRV-3 sequences. One had SRV-3 env sequences only, and another gag only. Immunoblotting studies with purified viruses as target antigens showed that six FV-PCR positive and one PCR-negative animal were seropositive and reacted with the principal FV gag precursors—Pr74/70gag, but all animals were seronegative to SRV-3 (one serum reacted indeterminately only with gp70 SU). SRV-3 infection is likely to have taken place long ago, because of the weak (if any) immune response, and apparently defective proviruses in two animals with either gag or env genes. During the past four decades, AGM infection with retroviruses in the wild was likely to have been stable. On the basis of our data, we suggest that during preparation of polio vaccines on AGM cells, retroviruses may have been activated in cells of some symptomless carriers, and contaminated polio vaccine stocks. RT-PCR analysis of old stocks are required to clarify this point. 1
2 3
4
5
Flügel RM. The molecular biology of the human spumavirus. In: Cullen BR, ed. Human retroviruses. Oxford: Oxford University Press, 1993: 193–214. Grant RF, Windsor SK, Malinak CJ, et al. Characterization of infection type D retrovirus from baboons. Virology 1995; 207: 292–96. Lagaye S, Vexiau P, Morozov V, et al. Human spumaretrovirus-related sequences in the DNA of leukocytes from patients with Graves disease. Proc Natl Acad Sci USA 1992; 89: 10070–74. Schweizer M, Turek R, Hahn H, et al. Markers of foamy virus infections in monkeys, apes, and accidentally infected humans: appropriate testing fails to confirm suspected foamy virus prevalence in humans. AIDS Res Hum Retrovir 1995; 11: 161–70. Morozov VA, Lagaye S, Lyakh L, ter Meulen J. Type D retrovirus markers in healthy Africans from Guinea. Res Virol 1996; 147: 341–51.
Laboratory of Cancer Virus Immunology (V Morozov), Cancer Research Center of Russia, 115478 Moscow, Russia; and Unité de Biologie des Retrovirus, Institut Pasteur, Paris, France
1705
We proposed thiamine deficiency causing Wernicke’s encephalopathy as an explanation for his symptoms. He was treated with 100 mg of thiamine as an intravenous bolus. Subsequently, 100 mg thiamine with 1 g of folate and multivitamins were administered in an intravenous infusion over 24 h. Within 12 h of starting treatment, improvement was noted. Within 48 h he was able to abduct each eye 90 degrees past the midline, and there was improvement in tandem walking. The encephalopathy was slower to resolve than the other neurological symptoms. Appetite response to thiamine supplementation was difficult to assess because of a strong behavioural component to the food refusal, but by 1 week he accepted a full diet. 1 month later, he showed nearcomplete recovery of all neurological functions. Thiamine deficiency is a potential risk in any chronically malnourished individual. Wernicke’s disease has been reported before in children who were fed thiamine-deficient infant formulae,1 and also in paediatric oncology patients who had extended periods of emesis and limited food intake related to chemotherapy.2–4 In general, this is a rare condition in children. Acute intravenous glucose loads may precipitate the clinical symptoms of Wernicke’s disease, by depleting thiamine stores. 1
2
3
4
Seear MD, Norman MG. Two cases of Wenicke’s encephalopathy in children: an under diagnosed complication of poor nutrition. Ann Neurol 1988; 24 (1): 85–87. Bruck W, Christen JH, Latomek H, Hanefeld F, Friede RL, Wernicke’s encephalopathy in a child with acute lymphoblastic leukemia treated with polychemotherapy. Clin Neuropath 1991; 10 (3): 134–36. Miyajima Y, Fukuda M, Kojima S, Matsuyama T, Shylaja N, Aso K. Wernicke’s encephalopathy in a child with acute lymphoblastic leukemia. Am J Ped Hematol-Oncol 1993; 15 (3): 331–34. Pihko H, Saarinen U, Paetu A. Wernicke encephalopathy—a preventable cause of death: report of two children with malignant disease. Pediat Neurol 1989; 5 (4): 237–42.
Departments of Neurology (A L Gropmans) and Psychiatry, Children’s National Medical Center, Washington, DC, and Department of Neurology, Georgetown University Hospital, Washington, DC 20010, USA
Latent foamy and simian retroviruses in healthy African green monkeys used in biomedical research V A Morozov, S Lagaye
For several decades, African green monkeys (AGMs) and macaques have been used as sources of cells and blood for vaccine trials. The health of animals is assessed visually and by serology for infections. However, even seronegative animals, especially from the wild, could be infected with latent viruses and retroviruses, so their biological material may be a source of infections. During the 1950s and 1960s primary kidney-cell cultures of wild AGMs and macaques were used worldwide for polio vaccine preparation. In some countries wild AGMs and macaques are still used. Foamy retroviruses (FVs) have been isolated from Old-World primates and are thought to be latent in their natural hosts.1 Simian type-D retroviruses (SRV) have been detected in Asian primates and are prevalent in colonyborn macaques. On the basis of limited immunological data, African primates and AGMs in particular were considered to be free of SRV infection. However, SRV has been isolated from Ethiopian baboons.2 SRVs induce severe immunodeficiency, especially in animals kept in primate research centres. FV and SRV are easily transmitted in vivo,
THE LANCET • Vol 351 • June 6, 1998
FV and SRV-3 sequences PCR amplified from the DNAs of healthy AGMs (A) Detection of FV int sequences by “nested” PCR and (B) detection of SRV-3 env sequences by PCR-Southern hybridisation with DIGlabelled env probe. Tracks 1–13=DNA from AGMs, +=DNA from FV (A) and SRV-3 (B) infected human cells (positive controls), ⫺=DNA from uninfected human cells (negative controls), M⫺=DIG-labelled DNA markers VI (Boehringer-Mannheim, Germany). Primers and conditions for “nested” PCR amplification of int FV specific sequences, and primers and probes for SRV-3 gag and env sequences amplification and detection were as described.4,5 Each 100 L reaction mixture contained 200 ng of DNA sample, 100 ng of each primer, 200 nmol/L of each deoxynucleotide, 1·5 mmol/L MgCI2 and 3 U of Taq polymerase (PerkinElmer, USA). For “nested” PCR, 5 L from the first PCR reaction was used. Positions and sizes of amplimers are given on the right.
but infection of man is still questioned.3–5 We surveyed FVs and SRV-3 markers in DNA and serum samples from 13 wild (SV40-negative) and apparently healthy AGMs from Kenya used for biomedical research. Samples were examined first by PCR with -globin primers. Screening for FVs sequences was by nested PCR with universal int-specific primers (provided by M Schweizer).4 Primers for SRV-3 amplification were as described:5 gag (positions 510–530, 1129–1109), and env (positions 6878–6898, 7459–7439). SRV-3 amplimers were Southern hybridised to digoxigenin (DIG)-labelled probes.5 FV sequences were found in seven of 13 AGMs (figure a, tracks 1, 2, 5–7, 10, 11). One animal contained FV and both gag (not shown) and env SRV-3 sequences. One had SRV-3 env sequences only, and another gag only. Immunoblotting studies with purified viruses as target antigens showed that six FV-PCR positive and one PCR-negative animal were seropositive and reacted with the principal FV gag precursors—Pr74/70gag, but all animals were seronegative to SRV-3 (one serum reacted indeterminately only with gp70 SU). SRV-3 infection is likely to have taken place long ago, because of the weak (if any) immune response, and apparently defective proviruses in two animals with either gag or env genes. During the past four decades, AGM infection with retroviruses in the wild was likely to have been stable. On the basis of our data, we suggest that during preparation of polio vaccines on AGM cells, retroviruses may have been activated in cells of some symptomless carriers, and contaminated polio vaccine stocks. RT-PCR analysis of old stocks are required to clarify this point. 1
2 3
4
5
Flügel RM. The molecular biology of the human spumavirus. In: Cullen BR, ed. Human retroviruses. Oxford: Oxford University Press, 1993: 193–214. Grant RF, Windsor SK, Malinak CJ, et al. Characterization of infection type D retrovirus from baboons. Virology 1995; 207: 292–96. Lagaye S, Vexiau P, Morozov V, et al. Human spumaretrovirus-related sequences in the DNA of leukocytes from patients with Graves disease. Proc Natl Acad Sci USA 1992; 89: 10070–74. Schweizer M, Turek R, Hahn H, et al. Markers of foamy virus infections in monkeys, apes, and accidentally infected humans: appropriate testing fails to confirm suspected foamy virus prevalence in humans. AIDS Res Hum Retrovir 1995; 11: 161–70. Morozov VA, Lagaye S, Lyakh L, ter Meulen J. Type D retrovirus markers in healthy Africans from Guinea. Res Virol 1996; 147: 341–51.
Laboratory of Cancer Virus Immunology (V Morozov), Cancer Research Center of Russia, 115478 Moscow, Russia; and Unité de Biologie des Retrovirus, Institut Pasteur, Paris, France
1705