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Two New Viruses Reported Belonging to AIDS Family
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NY Times
February 26, 2005
By LAWRENCE K. ALTMAN
BOSTON, Feb. 25 - American scientists said Friday that they had discovered two new human viruses in Africa that belong to the same family, retroviruses, as the virus that causes AIDS.
So far, the scientists said, the new viruses have not been linked to any disease, but they are being monitored out of concern that they or similar retroviruses might conceivably spawn another epidemic.
The viruses, found in rural Cameroon among people who hunt monkeys and other primates, were probably transmitted from the animals through blood from bites and scratches received in hunting, butchering and keeping the primates as pets, the scientists said at the 12th Annual Retrovirus Conference, which ended here on Friday.
The discoveries arose from studies undertaken out of concern that another retrovirus could emerge to mushroom into another global pandemic like AIDS. Many scientists say they believe that H.I.V., the AIDS virus, mutated from a simian virus that was transmitted from nonhuman primates to hunters and then spread widely through sex and contaminated needles.
In another report at the conference, scientists from the Centers for Disease Control and Prevention reported that the rate of H.I.V. infection had doubled among blacks in the United States over a decade, to 2 percent of the black population in 1999-2002 from 1 percent in 1988-1994. The rate among whites remained at 0.2 percent in that period.
Earlier studies have also shown a widening racial gap in the epidemic. Experts have cited poverty, drug addiction and limited access to health care.
The new survey also found that the lack of knowledge about a person's H.I.V. status was a bigger barrier to treatment than the lack of access to care.
One scientist who discovered the new viruses in Africa, Dr. Walid Heneine, a virologist at the disease centers, said his team was expanding its research to determine the health status of the infected people and of their sexual partners.
The team, which includes scientists from the Johns Hopkins University, is conducting additional tests to identify other novel viruses.
The studies show that "there is frequent ongoing transmission" from nonhuman primates, Dr. Heneine told reporters in an interview.
The retroviruses, named H.T.L.V.-3 and H.T.L.V.-4, for human T-lymphotropic virus, are the newest members of a class that can cause a wide spectrum of illnesses. The retrovirus numbered 1 is a cause of leukemia and inflammatory diseases, and it and H.T.L.V.-2 can lead to neurological disease, Dr. Heneine said.
H.I.V. belongs to a different group of retroviruses.
The two older viruses infect an estimated 22 million people, Dr. Heneine said, and about 5 percent of them develop illness. As with AIDS, the time from infection to disease can be as long as several decades.
Speaking of the two new retroviruses, Dr. Heneine said that "we do not know yet" whether they will be like the older two.
Although the ultimate aim is to prevent another virus from causing an AIDS-like pandemic, Dr. Heneine said, one concern is the potential spread of the new viruses through blood transfusions. Blood banks in Africa do not test for H.T.L.V. viruses before blood and blood products are transfused, he said.
In earlier studies, scientists have tested zookeepers, animal handlers, veterinarians and others to determine how often they were exposed to viruses from viruses known to exist in nonhuman primates.
A particular interest has been so-called foamy viruses, which are not known to cause disease in humans. They have been found in 2 percent to 5 percent of such workers, Dr. Heneine said.
He called that a high rate, because "such viruses are not supposed to be in humans."
Expanding their research to exposure in natural settings, the scientists studied 930 people in Cameroon who said they were exposed to freshly hunted primate bush meat. The participants answered a questionnaire and agreed to have their blood tested for viruses.
The scientists detected the new retroviruses by using antibody, genetic and other tests in the laboratory.
In identifying what is believed to be the first documented human infection of H.T.L.V-3, the scientists found that the virus was genetically similar to a simian virus, S.T.L.V.-3.
H.T.L.V.-4 is distinct from all known human or simian viruses, Dr. Heneine said.
The team also found that 11 other participants were infected with H.T.L.V.-1 and a simian virus also numbered 1, including strains of that virus not previously identified among humans.
The team plans to test an additional 4,000 people in rural Cameroon to determine the extent of any transmission among humans.
"Discovery of New Human T-Lymphotropic Viruses Reveals Frequent and Ongoing Zoonotic Retrovirus Introductions (to humans)"
In the Friday morning "Viral and Cellular Determinants of Pathogemnesis" oral abstract session researchers from the CDC et al reported this Late Breaker abstract (155LB).
Background: The entry of primate retroviruses into humans has lead to 2 pandemics (HIV and T-lymphotropic virus [HTLV]). It is believed that the emergence of these viruses has been limited by the rarity of successful cross-species transmission. However, little is known about the frequency of retroviral zoonoses (a disease in animals than can be transmitted to humans) and the mechanisms of retroviral emergence.
Methods: To examine the frequency of retrovirus cross-species transmission we examined blood specimens from 930 individuals who reported exposure to freshly hunted primate bush-meat in Cameroon. Plasma samples were screened serologically using an HTLV-1/2 EIA followed by confirmation with an HTLV Western blot assay. Peripheral blood lymphocyte DNA available from Western blot-reactive persons were then examined using PCR in several viral gene regions followed by phylogenetic analysis.
Results: Plasma samples from 90 persons (9.7%) were Western blot-reactive and proviral sequences were PCR-amplified from the peripheral blood lymphocyte DNA of 13 Western blot-reactive persons. Phylogenetic analysis revealed that 2 primate hunters were found to be infected with 2 novel viruses we designated HTLV-3 and HTLV-4. HTLV-3 falls within the diversity of STLV-3, a simian virus not seen before in humans. HTLV-4 is distinct from all known HTLV and STLV by the formation of a new phylogenetic lineage with high bootstrap support. Phylogenetic analysis showed that the 11 remaining persons were infected with a broad diversity of HTLV-1/STLV-1, including STLV-1 from mandrills (n=3) and other STLV-1 variants (n=2) not previously seen in humans.
Conclusions: We report that bush-meat hunters in Central Africa who are exposed to infected primates are regularly infected with novel HTLV. We discovered at least 6 viruses that had crossed from infected primates, including 2 novel human retrovirus species, HTLV-3 and HTLV-4. The findings demonstrate that cross-species transmission following primate exposure is not the rate-limiting step in retrovirus emergence and suggest that the emergence may be predicted by surveillance of human populations exposed to animal reservoirs.
AUTHORS: Nathan Wolfe*1, W Heneine2, J Carr3, A Garcia2, V Shanmugam2, U Tamoufe4, J Torimiro4, A Prosser2, M LeBreton4, EMpoudi-Ngole4, F McCutchan3, D Birx3, T Folks2, D Burke1, and W Switzer2. 1Johns Hopkins Univ Bloomberg Sch of Publ Hlth, Baltimore, MD, USA; 2CDC, Atlanta, GA, USA; 3US Military HIV Res Prgm, Rockville, MD, USA; and 4Johns Hopkins Walter Reed Cameroon Prgm., Yaunde
"Simian Foamy Virus Infection Among HIV-1+ Sex Workers and Blood Donors in Central Africa"
In poster abstract 308, CDC researchers reported finding simian foamy virus (SFV) was spread to sex workers, which CDC researchers say raises concerns about sexual transmission and public health consequences.
Background: The recognition that AIDS originated from nonhuman primates (NHP) heightens concerns associated with transmission of simian retroviruses to humans. Although recent studies document frequent infection with simian foamy virus among primate hunters in Cameroonand primate handlers in North America, little is known about the spread and geographic distribution of SFV outside these populations.
Methods: We tested 180 plasma samples collected from sex workers (n=97) in 1985, and sex workers (n=42) and tuberculosis (TB) and sexually transmitted disease (STD) patients (n=41) in 1999 to 2000 all from Kinshasa, Democratic Republic of Congo, and 179 plasma samples collected recently from anonymous blood donors from Yaounde, Cameroon. Plasma samples were screened for SFV antibodies by ELISA and reactive specimens were tested further by a Western blot (WB) assay that can detect monkey- and ape-type SFV reactivity. Polymerase chain reaction (PCR) amplification of DNA from peripheral blood lymphocytes (PBL) and phylogenetic analysis was used to define the NHP species origin of SFV.
Results: One of 39 (0.72%) sex workers was SFV WB positive. This specimen was collected in 1985 from an HIV-1-infected person. One of 79 (0.56%) of Cameroonian blood donors was also SFV WB-positive and HIV-1 positive. An SFV integrase sequence was amplified from the PBL DNA of the SFV-positive blood donor. Phylogenetic analysis showed SFV infectionoriginating from a mandrill, a NHP species that is frequently hunted and consumed in Cameroon.
Conclusions: Our study documents SFV infection among different Central African populations. The finding of SFV in samplescollected recently and in 1985 from blood donors and sex workers suggests long-standing infection and opportunities for blood borne and sexual transmission. The observed co-infection with SFV & HIV heightens the importance of defining the clinical and public health consequences of these infections.
Authors: W Switzer, M Kalish, C Yang, A Garcia, A Wright, T Folks, and W Heneine*. CDC, Atlanta, GA, USA.
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