Kunjin virus replicon-based vaccines expressing Ebola virus glycoprotein GP protect the guinea pig against lethal Ebola virus infection.

Pre- or postexposure treatments against the filoviral hemorrhagic fevers are currently not available for human use. We evaluated, in a guinea pig model, the immunogenic potential of Kunjin virus (KUN)-derived replicons as a vaccine candidate against Ebola virus (EBOV). Virus like particles (VLPs) containing KUN replicons expressing EBOV wild-type glycoprotein GP, membrane anchor-truncated GP (GP/Ctr), and mutated GP (D637L) with enhanced shedding capacity were generated and assayed for their protective efficacy. Immunization with KUN VLPs expressing full-length wild-type and D637L-mutated GPs but not membrane anchor-truncated GP induced dose-dependent protection against a challenge of a lethal dose of recombinant guinea pig-adapted EBOV. The surviving animals showed complete clearance of the virus. Our results demonstrate the potential for KUN replicon vectors as vaccine candidates against EBOV infection.

Defective humoral responses and extensive intravascular apoptosis are associated with fatal outcome in Ebola virus-infected patients.

Ebola virus is very pathogenic in humans. It induces an acute hemorrhagic fever that leads to death in about 70% of patients. We compared the immune responses of patients who died from Ebola virus disease with those who survived during two large outbreaks in 1996 in Gabon. In survivors, early and increasing levels of IgG, directed mainly against the nucleoprotein and the 40-kDa viral protein, were followed by clearance of circulating viral antigen and activation of cytotoxic T cells, which was indicated by the upregulation of FasL, perforin, CD28 and gamma interferon mRNA in peripheral blood mononuclear cells. In contrast, fatal infection was characterized by impaired humoral responses, with absent specific IgG and barely detectable IgM. Early activation of T cells, indicated by mRNA patterns in peripheral blood mononuclear cells and considerable release of gamma interferon in plasma, was followed in the days preceding death by the disappearance of T cell-related mRNA (including CD3 and CD8). DNA fragmentation in blood leukocytes and release of 41/7 nuclear matrix protein in plasma indicated that massive intravascular apoptosis proceeded relentlessly during the last 5 days of life. Thus, events very early in Ebola virus infection determine the control of viral replication and recovery or catastrophic illness and death.

Identification of a new human immunodeficiency virus type 1 distinct from group M and group O.

A highly divergent HIV-1 isolate, designated YBF 30, was obtained in 1995 from a 40-year-old Cameroonian woman with AIDS. Depending on the genes studied, phylogenetic analysis showed that YBF30 branched either with SIVcpz-gab or between SIVcpz-gab and HIV-1 group M. The structural genes and tat, vpr, and nef of YBF30 are approximately equidistant from those of HIV-1 group M and SIVcpz-gab. In contrast, vif and rev are closer to HIV-1 group M, and vpu is highly divergent. Using a YBF30 V3 loop peptide enzyme immunoassay, we screened 700 HIV-1-positive sera collected in Cameroon; three reacted strongly with the YBF30 peptides and one was confirmed as being related to YBF30 by genetic analysis of a pol fragment. YBF30 is as distinct from SIVcpz-gab as it is from HIV-1 group M and can thus be considered as the prototype strain of a new human immunodeficiency virus group.

[Filovirus]. / Les filovirus.

Since forty years Marburg and Ebola viruses emerge frequently in Africa and are responsible of viral hemorragic fever outbreaks with high mortality rate. Despite intensive research programs, these viruses remain mysterious: the reservoir is not clearly defined, and the mechanisms leading to their high pathogenicity are poorly understood; a defective or inadapted immune response seems to be the main factor. No specific treatment nor vaccine are available for humans. But encouraging results have been obtained in the treatment of filovirus infections in non human primate model with different products, as recombinant nematode anticoagulant protein, anti sens phosphorodiamidate morpholino oligomers or small interfering RNA.As vaccines, recombinantVSV expressing the GP of filovirus or adenovirus expressing the GP and NP of filovirus are very promising in macaque models.

Diversity of V3 region sequences of human immunodeficiency viruses type 1 from the central African Republic.

Nucleotide sequences of the central portion of gp120, including the third hypervariable (V3) loop, were obtained from lymphocytes cocultivated with SupT1 cells from 29 AIDS patients in Bangui, Central African Republic. These sequences displayed significantly greater diversity (average distance, 23%) than has been previously observed in isolates from comparably restricted geographical areas. Isolates belonging to four major subtypes of HIV-1 were found; the only subtype not represented was the North American/European subtype B. Unlike the situation in Zaire and Uganda, where subtypes A and D account equally for virtually all isolates of HIV-1, the predominant subtypes in the Central African Republic, accounting for two-thirds of the isolates, were subtypes A (10 isolates) and E (9 isolates). Subtype E represents a group of variants that have previously been found only in Thailand. Only one isolate belonging to subtype D was found. Also recovered were two isolates of subtype C, a subtype associated with southern African and Indian isolates but not previously detected in central Africa. These isolates, although clearly clustering with subtype C, formed a distinct subset, differing from one another by 8.8% and from the Indian and South African subtype C isolates by an average of 22.5%. High interpatient, intrasubtype variation was also seen among the CAR subtype A (average pairwise difference, 19.3%) and subtype E (10.9%) isolates. The diversity of V3 sequences in this set has implications for immunization protocols that rely on the recognition of V3. This study underscores the necessity of basing intervention strategies on knowledge of the particular sequences present in the target population or geographical area.

Human T-lymphotropic virus type I excretion and specific antibody response in paired saliva and cervicovaginal secretions.

Paired sera, salivas, and cervicovaginal secretions from 17 HTLV-I-infected women (10-75 years) were evaluated for total IgA, IgG, IgM, for IgA and IgG to whole HTLV-I lysate, for albumin, and for tax-rex proviral HTLV-DNA. IgG to HTLV-I were constantly detected, with much higher titers in serum (mean titer: 97,800) than in saliva (53) or in cervicovaginal secretions (216). IgA to HTLV-I were detected in only 12 (70%) sera, 6 (35%) salivas, and 8 (53%) cervicovaginal secretions, with higher titers in serum (75) than in saliva (8). Using the relative coefficient of excretion by reference to albumin, as well as the comparison of specific activities, the HTLV-I-specific IgG appeared primarily originating from serum, whereas IgA to HTLV-I were primarily locally produced. Salivary synthesis of IgG to HTLV-I occurred in both patients with a sicca syndrome attesting salivary glands impairment. Local excretions of total IgA, IgG, and IgM evaluated in body fluids were normal. HTLV DNA was detected in 4 (24%) salivas and in 3 (20%) cervicovaginal secretions, always in patients demonstrating local synthesis of HTLV-I-specific IgA or IgG. HTLV-I excretion elicits a weak local immune response to HTLV-I in saliva as well as in cervicovaginal secretions, which could be relevant for HTLV-I transmission via body fluids.

Mutations in CCR5-coding sequences are not associated with SIV carrier status in African nonhuman primates.

African monkeys can be naturally infected with SIV but do not progress to AIDS. Since mutations in the human CCR5 gene have been shown to influence susceptibility to HIV infection and disease progression, we have now investigated whether mutations in CCR5-coding sequences in African nonhuman primates can explain species-specific differences in susceptibility to lentiviral infection. The animals studied comprise chronically infected monkeys corresponding to four natural hosts of SIV (Cercopithecus aethiops, Cercopithecus pygerythrus, Cercopithecus sabaeus, and Cercopithecus tantalus), noninfected animals from three species that are known to be susceptible to SIV infection (Cercopithecus patas, Cercopithecus Ihoesti, and Pan troglodytes), and monkeys of six species that do not carry SIV in the wild (Cercocebus galeritus, Cercocebus aterrimus, Cercopithecus ascanius, Cercopithecus nictitans, Cercopithecus neglectus, and Cercopithecus cephus). We observed a high degree of genetic divergence among the species. The rate of accumulation of amino acid mutations was, however, not higher in SIV carriers than in other nonhuman primates. No homozygous premature stop codons, deletions, or frameshift mutations were detected. In at least two animals, one infected AGM (Cercopithecus tantalus) and one noninfected monkey (Cercocebus aterrimus), the CCR5 alleles identified encode functional proteins, as they were identical in terms of amino acid sequence to that of functional CCR5 reported in the literature. We found no other consistent differences in the genetic variability of CCR5-coding sequences between the nonhuman primates that are carriers of SIV and those that are not.

Immunogenicity of variable regions of the surface envelope glycoprotein of HTLV type I and identification of new major epitopes in the 239-261 region.

The reactivity of sera of 96 individuals infected with human T-cell leukemia virus type I (HTLV-I) was tested against various synthetic peptides corresponding to the gp46 immunodominant antigenic domains: residues 86-107, 175-199, and 239-261. The frequency of reactive sera was higher for 175-199 (93%) than for 239-261 (78%) or 86-107 (24%) with some variations in geographical regions and in diseases. The region 239-261 was extensively analyzed and five (linear or conformational) epitopes were found. The reactivity of sera toward functional or immunodominant domains may depend on the sequence of the infecting virus, and the role of three frequent substitutions (asparagine by tyrosine, proline by serine, and serine by proline or leucine at positions 93, 192, and 250 respectively) was established. Finally, the role of the genetic background of the host may condition the humoral immune response as individuals infected by HTLV-Is harboring the same predicted gp46 peptide sequence may recognize one, several, or all regions examined.

Phylogenetic analysis of SIV and STLV type I in mandrills (Mandrillus sphinx): indications that intracolony transmissions are predominantly the result of male-to-male aggressive contacts.

Natural SIVmnd and STLVmnd infections of mandrills in a colony at the Centre International de Recherches Médicales de Franceville (CIRMF) in Gabon were investigated by genetic analysis to determine the extent of intracolony transmission. SIVmnd pol sequence analysis indicates that the six strains present in the colony belong to the SIVmnd lentivirus subgroup previously defined according to the only available prototype sequence (SIVmndGB1), which originated from the same colony. The intraanimal nucleotide diversity (1.1-3.1%) was similar in range to that reported in individuals infected by other HIV/SIVs. The interanimal diversity (0.5-4.3%) was not significantly different from that observed in each individual mandrill, indicating an epidemiological link among the SIVmnd isolates of distinct animals within the colony. Phylogenetic analysis of these isolates, together with seroepidemiological and behavior surveillance within the colony, indicates a predominant male-to-male transmission of SIVmnd that probably occurred during bouts of interanimal aggression. Moreover, our results suggest one case of vertical transmission of SIVmnd from a naturally infected founder female to one of her six offspring. The first genetic analysis of STLV isolates from mandrills is also reported here. Partial tax/rex sequences were used to evaluate the diversity between seven STLVmnd isolates and their phylogenetic relationships with other known strains of human and nonhuman primate T cell leukemia virus, types I and II (PTLV-I/II). They all belong to the PTLV-I subtype, but two genetically distinct STLVmnd groups were evidenced within the mandrill colony. The phylogenetic analyses of the STLVmnd isolates, together with seroepidemiological and behavior surveillance of the mandrills, indicate that intracolony transmissions of STLVmnd are also predominantly the result of male-to-male aggressive contacts.

Characterization and titration of an HIV type 1 subtype E chimpanzee challenge stock.

A subtype E human immunodeficiency virus type 1 (HIV-1) isolate from the Central African Republic (E/90CR402) was adapted to growth on chimpanzee peripheral blood mononuclear cells (PBMCs) by cocultivation of irradiated, infected human PBMCs with chimpanzee PBMCs. The resulting virus was passaged in chimpanzee PBMCs to generate a stock of chimpanzee-adapted virus. Although its V3 region sequence was identical to that of the parental isolate, the chimpanzee-adapted virus had a syncytium-inducing phenotype as opposed to the non-syncytium-inducing phenotype of the parental virus. After demonstrating in one animal each that the passaged virus could infect chimpanzees following intravenous (i.v.) or cervical inoculation, the i.v. infectious titer of the stock was determined. Exposure of three chimpanzees to different doses of the virus indicated that the titer was between 2 and 5 TCID50. Thus, the HIV-1 E/90CR402 chimpanzee challenge stock established persistent infections in chimpanzees by both the i.v. and genital routes and should be valuable for future HIV-1 vaccine studies to evaluate cross-protection between HIV-1 subtypes.

Antibodies to Campylobacter flagellin recognize epitopes common to phase 1 and phase 2 flagella.

We used a simple method to obtain purified flagellin from Campylobacter, suitable for an immunization procedure in mice. Western blot analysis of cross-reacting antibodies showed that there were epitopes common to phase 1 and 2 flagellins. Analysis by ELISA suggested that certain common flagellar epitopes are conformational, and antibody immobilization tests confirmed that common surface-exposed epitopes exist in a region of flagella necessary for conferring motility to the bacteria.

Biotype and Lior serogroup distribution of enteric Campylobacter isolated from children in Bangui (Central African Republic), and comparison with Penner serotypes.

The new extended biotyping scheme of Lior as well as the slide agglutination technique were applied to 209 strains of enteric Campylobacter isolated from children in Bangui (Central African Republic). Three biotypes of C. jejuni and 2 biotypes of C. coli were identified among the strains; 31.1% were C. jejuni I, 11% C. jejuni II, 2.4% C. jejuni III, 44% C. coli I and 11.5% C. coli II. We were able to serotype 71.3% of the strains with 20 immune sera prepared against strains of Campylobacter isolated previously; 63% of the strains were distributed among the ten most common serogroups. No significant difference was observed in the distribution of biotypes or serogroups between strains from healthy and diarrhoeic children. Comparison of Lior serogroups with Penner serotypes showed that different Penner serotypes may correspond to a Lior serogroup and vice versa.

Leptospirosis and Ebola virus infection in five gold-panning villages in northeastern Gabon.

An exhaustive epidemiologic and serologic survey was carried out in five gold-panning villages situated in northeastern Gabon to estimate the degree of exposure of to leptospirosis and Ebola virus. The seroprevalence was 15.7% for leptospirosis and 10.2% for Ebola virus. Sixty years after the last seroepidemiologic survey of leptospirosis in Gabon, this study demonstrates the persistence of this infection among the endemic population and the need to consider it as a potential cause of hemorrhagic fever in Gabon. There was no significant statistical correlation between the serologic status of populations exposed to both infectious agents, indicating the lack of common risk factors for these diseases.

Lympho-cutaneous Kaposi's sarcoma in an African pediatric AIDS case.

A case of disseminated Kaposi's sarcoma with lymphoid and mucocutaneous involvement in an African infant with acquired immune deficiency syndrome is reported. The child died within 2 months after recognition.

PIP: Co-infection with acquired immunodeficiency syndrome (AIDS) and Kaposi's sarcoma is not uncommon in Europe, but is rare in Africa and not previously reported in infants. This article documents the case of an 11-month-old African boy with lymphocutaneous Kaposi's sarcoma. The infant was brought to a hospital in the Central African Republic with chronic diarrhea and disseminated lymphadenopathy. Also present were fever, cough, weight loss, a gingivostomatitis with herpes-like vesicles, hepatomegaly, splenomegaly, and cervico-axillo-inguinal lymphadenopathy. The adenopathies 1st occurred when the infant was 7 months of age and were followed 1 month later by the emergence of 12 dark brown or black velvet raised cutaneous nodules. The diagnosis of Kaposi's sarcoma was confirmed by lymph node and skin nodule biopsies. Also indicative of Kaposi's sarcoma was the presence of abortive vascular foci at a distance from the skin's surface and the cell proliferation. Both the infant and his asymptomatic mother were seropositive for antibodies to human immunodeficiency virus (HIV)-1. The skin lesions in this case presented the special infiltrative characteristic of AIDS-related Kaposi's sarcoma. The infant died 2 months after presentation at the hospital. By the last weeks of his life, the cutaneous nodules had covered the entire body. Death was from pleuropneumopathy. Given the high prevalence of HIV-1 infection in the Central African Republic, more such cases can be expected.

A cohort study of enteric campylobacter infection in children from birth to two years in Bangui (Central African Republic).

A cohort of 111 children from Bangui, Central African Republic, was followed for enteric campylobacter infection from birth until the age of 2 years. Stools were examined at each episode of diarrhoea, and bi-weekly up to the age of 6 months irrespective of the presence of diarrhoea. 349 episodes of diarrhoeal illness were recorded (1.6 per child-year). Campylobacters were isolated from 41 (11.7%) of the 349 episodes, but in half of them another enteric pathogen was also isolated. Campylobacters were statistically associated with diarrhoea only before the age of 6 months. Bi-weekly sampling up to this age detected 75 infections (1.3 per child-year), yet only 12 (16%) were associated with diarrhoea. Campylobacter coli was isolated slightly more often (51%) than C jejuni (49%); biotyping and serogrouping showed that no strain was especially associated with disease. Fewer children who had campylobacter infection before the age of 6 months suffered campylobacter diarrhoea between 6 and 24 months of age than those who did not, but the difference did not reach statistical significance. A significantly higher rate of isolation was found in the homes of infected children (human and animal contacts) than of non-infected children. Campylobacter infections were statistically associated with the presence of live poultry and the lack of piped water in homes.

Seroprevalence of four sexually transmitted diseases in a semi-urban population of Gabon.

Using the cluster-sampling method, the authors estimated the seroprevalence of 4 sexually transmitted diseases (STDs) among the sexually active general population in a city of 30,000 inhabitants in the east of Gabon. The seroprevalences were 2% for HIV-1, 13.8% for hepatitis B, 8.6% for Treponema pallidum and 59.6% for Chlamydia trachomatis. The seroprevalences of hepatitis B and chlamydia were stable over time and similar to those registered in other countries of central Africa. On the other hand, the seroprevalence of T. pallidum is notably low in comparison with these countries and seems to be decreasing. The seroprevalence of HIV-1 is also low but has doubled in 8 years in the city. Immigrant women from west Africa were a high-risk group for STDs but more generally, cohabiting was a risk factor for women.

PIP: Findings are presented from a seroprevalence survey of HIV, hepatitis B, syphilis, and chlamydia conducted in Franceville, Gabon, during 2 days in January 1996, in a representative sample of the sexually active general population aged 14-55 years. 456 usable sera were collected from 457 individuals recruited in 20 clusters of 25 people each. Franceville is a city of approximately 30,000 inhabitants. 2% were infected with HIV-1, 13.8% with hepatitis B, 8.6% with Treponema pallidum, and 59.6% with Chlamydia trachomatis. The seroprevalences of hepatitis B and chlamydia were stable over time and similar to those reported in other central African countries. However, the seroprevalence of T. pallidum is quite low relative to those other countries and appears to be decreasing. The seroprevalence of HIV-1 is also low, but twice the level observed in 1988.

[Epidemics of Ebola haemorrhagic fever in Gabon (1994-2002). Epidemiologic aspects and considerations on control measures]. / Les epidémies de fièvre hémorragique due au virus Ebola au Gabon (1994 - 2002): aspects epidémiologiques et réflexions sur les mesures de contrôle.

Based on the description of the four Ebola haemorrhagic fever epidemics (EHF) occurred in Gabon between 1994 and 2002, the authors are considering the cultural and psycho-sociological aspects accounting for the difficulty to implement control measures. On the whole, the result of these raging epidemics came up to 207 cases and 150 dead (lethality: 72%). Analysing precisely the aspects of the third epidemic and pointing up the possible factors explaining its spreading far beyond its epicentre, the authors bring about the limits of measures not always understood by local populations. The discussion will deal with the possibilities of a better surveillance, a quick management of intervention means including a regional permanent pre-alert and taking into account the issue raised by the possible Ebola virus endemic.

[HTLV-1 infection in time and space]. / HTLV-1 dans le temps et dans l'espace.

Human T-cell leukemia virus type 1 (HTLV-1) is a member of the Oncoretrovirinae family containing several viruses that have been associated with a low incidence of leukemia and sarcoma in mammals. Primates are susceptible to viruses of genera HTLV (humans) and STLV (other primates). The high degree of homology in genomic arrangement of HTLV and STLV is probably due to the existence of a common simian ancestor. Most infections are asymptomatic but a few cases exhibit blood diseases, e.g., T-lymphoma or T-cell leukemia, or neurologic disease, mainly, HTLV-1 associated myelopathy and tropical spastic paraparesia (HAM-TSP). The four major modes of viral transmission are vertical transmission from mother to child either in utero or, more commonly, during breastfeeding, sexual intercourse, blood transfusion, and intravenous drug use. Geographic distribution of HTLV-1 and its confinement to a few well-defined ecosystems have yet to be explained. Diagnosis is now easy and can reduce transmission by intravenous drugs use. Development of a vaccine seems possible given the low genetic variability of this virus.

[Biohazards due to Orthopoxvirus: should we re-vaccinate against smallpox?]. / Les biorisques liés aux Orthopoxvirus: faut-il revacciner contre la variole?

Although the WHO declared global smallpox eradication in 1980, the Orthopoxvirus remains a source of concern for several reasons. Firstly, stocks of the smallpox virus have been preserved for experimental use (at least officially in the USA and Russia) so that an escaped isolate could lead to reemergence and spread of the disease worldwide. Secondly discontinuation of smallpox vaccination programs has led to dwindling acquired immunity in the world population thus raising the risk of epidemic extension of several Orthopoxvirus zoonoses (e.g., monkeypox). Thirdly stocks of camelpox virus which is very similar to Smallpox virus and was intended for biological warfare were discovered during the Gulf War in 1991 and pose a potentially serious threat. Finally official stocks of Smallpox virus could be stolen and used by bioterrorists. Thus reemergence of Orthopoxvirus including smallpox, monkeypox, cowpox, and camelpox is a real danger and contingency planning is needed to define prophylactic and therapeutic strategies to prevent and/or stop an epidemics. Adverse effects from earlier smallpox vaccine (vaccinia) in healthy people or immunocompromised people (congenital or acquired as in HIV infected patients) are absolute contraindications to smallpox vaccination at this time. Further research is needed to develop new vaccines (e.g., attenuated isolates of vaccinia) and effective treatment. This is the only valid reasons for postponing planned destruction of remaining Smallpox virus stocks.

[Ebola: a virus endemic to central Africa?]. / Ebola: un virus endemique en Afrique centrale?

From October 2001 to March 2002, an outbreak of Ebola haemorrhagic fever occurred in the North-Eastern Gabon (63 cases) and neighbouring Congo (57 cases). It was the fourth epidemic in North Eastern Gabon since 1994. Meanwhile this outbreak differed from the previous epidemics: at least five different emerging sources of the virus in the human population were observed from the local fauna resulting in fears of an endemic Ebola virus in the area. The control of the outbreak was uneasy because of the unfriendly attitude of the local population related to the restrictive measures for the isolation of suspected patients and the epidemiological surveillance. Such rejection process emphasizes the need of a continuous increasing public awareness.