Evaluation of the Combined Effect of Heterodera glycines and Macrophomina phaseolina on Soybean Yield in Naturally Infested Fields with Spatial Regression Analysis and in Greenhouse Studies.

Heterodera glycines, the soybean cyst nematode, and Macrophomina phaseolina, causal agent of charcoal rot, are economically important soybean pathogens. The impact and effect of these pathogens on soybean yield in coinfested fields in the Midwest production region is not known. Both pathogens are soilborne, with spatially aggregated distribution and effects. Spatial regression analysis, therefore, is an appropriate method to account for the spatial dependency in either the dependent variable or regression error term from data produced in fields naturally infested with H. glycines and M. phaseolina. The objectives of this study were twofold: to evaluate the combined effect of H. glycines and M. phaseolina on soybean yield in naturally infested commercial fields with ordinary least squares and spatial regression models; and to evaluate, under environmentally controlled conditions, the combined effect of H. glycines and M. phaseolina through nematode reproduction and plant tissue fungal colonization. Six trials were conducted in fields naturally infested with H. glycines and M. phaseolina in Ohio. Systematic-grid sampling was used to determine the population densities of H. glycines and M. phaseolina, and soybean yield estimates. Though not used in any statistical analysis, M. phaseolina colony forming units from plant tissue, charcoal rot severity, and H. glycines type were also recorded and summarized. In two greenhouse experiments, treatments consisted of H. glycines alone, M. phaseolina alone, and coinfestation of soybean with both pathogens. Moran's I test indicated that the yield from five fields was spatially correlated (P < 0.05) and aggregated. In these fields, to account for spatial dependence, spatial regression models were fitted to the data. Spatial regression analyses revealed a significant interaction effect between H. glycines and M. phaseolina on soybean yield for fields with high initial population densities of both pathogens. In the greenhouse experiments, H. glycines reproduction was significantly (P < 0.05) reduced in the presence of M. phaseolina; however, soybean tissue fungal colonization was not affected by the presence of H. glycines. The direct mechanisms by which H. glycines and M. phaseolina interact were not demonstrated in this study. Future studies must be conducted in the field and greenhouse to better understand this interaction effect.

HIV-1 Antiretroviral Drug Resistance in Pregnant Women in Jamaica: A Preliminary Report.

This preliminary report sought to provide insight into the genetic diversity of human immunodeficiency virus drug resistance (HIVDR) in Jamaica. This was done by investigating the genetic diversity associated with drug resistance in pregnant women living with HIV attending antenatal clinics in Kingston, Jamaica. Blood samples were collected and viral RNA were extracted and analysed. The protease and reverse transcriptase (Pro-RT) genes were amplified using the nested polymerase chain reaction (PCR) method. Polymerase chain reaction amplicons were obtained for nine of 16 patients (56%), of which five (55%) were antiretroviral (ARV) drug naïve and four (45%) were treatment experienced. Three minor protease resistant-conferring mutations (A71AT, A71V, A71T) and five mutations conferring high to low-level resistance (K219EK, T69S, K103S, G190A and K103N) were detected in the RT region. More than 50% of the resistance mutations found were detected in ARV drug naïve individuals, implying that viruses are being transmitted with the ARV resistance. These preliminary results will inform the health practitioners of the level of drug resistance that is being transmitted as well as strengthen the need to initiate a national baseline survey on HIVDR in Jamaica.

First molecular surveillance report of HIV type 1 in injecting drug users and female sex workers along the U.S.-Mexico border.

HIV prevalence is increasing among high-risk populations in the Mexican-U.S. border cities of Tijuana and Ciudad Juarez. In 2005, the molecular epidemiology of HIV-1 was studied among injecting drug users (IDU) and female sex workers (FSW) in these cities, which are corridors for over two-thirds of the migrant flow between Mexico and the United States. Eleven samples (eight IDU and three FSW) were successfully amplified, sequenced, and analyzed. The results revealed that all 11 samples were subtype B. There was no phylogenetic clustering or separation of the strains between IDU and FSW or between Tijuana and Ciudad Juarez nor was the Mexican strain phylogenetically distinct from other subtype B strains. Two of three drug naive FSWs had low-level HIV-1 resistance mutations. This community-based study demonstrated that HIV-positive IDUs and FSWs in Ciudad Juarez and Tijuana were predominantly infected with subtype B. Further prevalence studies on HIV-1 resistance mutations among FSWs in these border cities are warranted.

Seroprevalence of and risk factors for HIV-1 infection among female commercial sex workers in South America.

OBJECTIVE: Assessment of HIV prevalence and associated risk behaviours among female commercial sex workers (FCSW) across major cities in South America. METHODS: Seroepidemiological, cross sectional studies of 13 600 FCSW were conducted in nine countries of South America during the years 1999-2002. Participants were recruited in brothels, massage parlours, hotels, and streets where anonymous questionnaires and blood samples were collected. HIV infection was determined by enzyme linked immunosorbent assay (ELISA) screening and western blot confirmatory tests. RESULTS: The overall HIV seroprevalence was 1.2% (range 0.0%-4.5%). The highest HIV seroprevalences were reported in Argentina (4.5%) and Paraguay (2.6%); no HIV infected FCSW were detected in Venezuela and Chile. Consistent predictors of HIV seropositivity were: (1) a previous history of sexually transmitted infections (STI, AORs = 3.8-8.3), and (2) 10 years or more in commercial sex work (AORs = 2.2-24.8). In addition, multiple (> or =3) sexual contacts (AOR = 5.0), sex with foreigners (AOR = 6.9), use of illegal drugs (AOR = 3.2), and marijuana use (AOR = 8.2) were associated with HIV seropositivity in Southern Cone countries. CONCLUSIONS: Consistently low HIV seroprevalences were detected among FCSW in South America, particularly in the Andean region. Predictors of HIV infection across the continent were STI and length of commercial sex work; however, use of illegal drugs, especially marijuana, and sexual contacts with foreigners were also found to be associated risk factors in the Southern Cone region. Interventions for the control of HIV and other STI need to be region and country specific; drug use appears to have an ever increasing role in the spread of HIV among heterosexually active populations.

Molecular epidemiology of HIV type 1 in Chile: differential geographic and transmission route distribution of B and F subtypes.

We examined the genetic makeup of 221 HIV-1 strains from Chilean persons living with HIV/AIDS by HMA and DNA sequencing of the env gene: 143 cases were infected by sexual contact with an already-infected partner, 76 were infected by mother-to-child transmission, and 2 were transfusion related. We found env HIV-1 subtype B in 202 cases (91.4%) and subtype F in 19 cases (8.6%). Subtype B strains were found throughout the country whereas subtype F viruses were predominantly found in cases from the metropolitan/central to the northern regions of Chile (p < 0.01). Chilean F subtypes clustered in two different groups: viruses from the central region clustered with F subtypes from Argentina, Uruguay, and Brazil, and viruses from the northern region, which independently segregated from other South American and European F strains. All of the 59 men having sex with men (MSM) were infected with B subtype strains whereas 7 (9.2%) and 12 (15.8%), respectively, of heterosexually infected females and children were infected with F subtype strains (p < 0.01). It appears that F subtype strains have been introduced into Chile by separate heterosexual transmission events from other nearby countries in the Southern Cone whereas B subtype strains have continued to persist predominantly among MSM.

Seroprevalence of and risk factors for HIV-1 infection among South American men who have sex with men.

OBJECTIVES: Sex among men constitutes an important route of transmission for HIV type 1 (HIV-1) in Latin America. Seeking better understanding of risk behaviours in this region, we determined the seroprevalence, potential risk factors, and geographic distribution of HIV-1 among groups of men who have sex with men (MSM). METHODS: Seroepidemiological, cross sectional studies of 13,847 MSM were conducted in seven countries of South America during the years 1999-2002. Volunteers were recruited in city venues and streets where anonymous questionnaires and blood samples were obtained. HIV-1 infection was determined by enzyme linked immunosorbent assay (ELISA) screening and western blot (WB) confirmatory tests. RESULTS: HIV-1 seroprevalence varied widely (overall 12.3%, range 11.0%-20.6%). The highest HIV-1 seroprevalence was noted in Bolivia (20.6%) and the lowest in Peru (11.0%). Predictors of HIV-1 infection varied among countries; however, a history of previous sexually transmitted disease (STD) was associated with a consistent increased risk (ORs=1.9-2.9, AORs=1.8-2.7). Multiple weekly sexual contacts was found to represent a secondary risk factor in Ecuador, Peru, and Argentina (ORs=1.6-2.9, AORs=1.6-3.1), whereas use of drugs such as cocaine was found to increase risk in Bolivia, Uruguay, and Paraguay (ORs=2.5-6.5, AORs=2.6-6.1). CONCLUSION: The results of this study illustrate an elevated HIV-1 seroprevalence among MSM participants from Andean countries. A previous STD history and multiple partners predicted HIV-1 infection in the seven countries of South America. In Southern Cone countries, HIV-1 infection was also associated with use of illegal drugs such as cocaine.

Documentation of subtype C HIV Type 1 strains in Argentina, Paraguay, and Uruguay.

HIV subtypes B, F, and BF recombinants have been previously reported in South America. This report describes the presence of HIV-1 subtype C infection in the countries of Argentina, Uruguay, and Paraguay dating back to at least 1999. Surveillance for uncommon non-B/non-F subtype viruses circulating in South America has been conducted in samples obtained from nine countries. Peripheral blood mononuclear cells (PBMC), dried filter paper (FP), and fresh blood (FB) samples were collected from HIV-positive patients from Ecuador, Colombia, Venezuela, Peru, Chile, Bolivia, Argentina, Uruguay, and Paraguay. From a total of 2962 HIV seropositive samples examined during a 9-year period (1995-2003), only 11 (0.4%) were found to be infected with non-B/non-F HIV variants. Eight of these 11 strains were determined to be subtype C by heteroduplex mobility assay (HMA). Five of these 8 strains were further characterized by sequencing and phylogenetic analysis of the protease (Pro) and reverse transcriptase (RT) region of the genome and two were sequenced full length. One of the strains was found to be a unique BC recombinant. The spread of a third subtype of HIV, subtype C, should raise the question of its potential future role in the HIV epidemic in this region.

Circulating recombinant form CRF02_AG in South America.

With the objective of monitoring the distribution of HIV-1 subtypes and circulating recombinant forms (CRFs)in South America, population-based surveillance studies were performed in seven countries. Peripheral blood mononuclear cell, filter paper, fresh blood, and cocultivation samples were collected from HIV-positive patients from Colombia, Ecuador, Peru, Bolivia, Chile, Argentina, and Uruguay, during a 7-year period(1995-2001). DNA was prepared and HIV envelope subtypes were determined by heteroduplex mobility as-say and DNA sequencing from 1289 HIV-positive samples. While subtypes B and F were the most commonly observed subtypes, two CRF02_AG strains were detected, in Ecuador. This is the first report of the existence of this CRF in South America.

Mother-to-child HIV type 1 transmission in Argentina: BF recombinants have predominated in infected children since the mid-1980s.

The molecular epidemiology of HIV-1 in Argentina is more complex than was previously appreciated. One circulating recombinant form, CRF12_BF, and many related BF recombinant forms predominate in the capital city, Buenos Aires. This study of HIV-1 subtypes acquired perinatally between 1984 and 2000 has permitted, for the first time, a reconstruction of the history of BF recombination in Argentina. Sequencing of a partial genome region from the beginning of vpu to the beginning of env(gp120), which spans a breakpoint common in most contemporary Argentine BF recombinants, enabled samples to be rapidly screened. Among 23 children born between 1984 and 2000, 15 including 1 child born in 1986, harbored a BF recombinant. Thirteen of the 15 recombinants shared a common breakpoint at the 5' end of env(gp120). Full genome sequencing of two viruses, from 1986 and 1987, respectively, revealed them to be genetically related but not identical to CRF12_BF. Both contained more subtype B sequence than did CRF12_BF. BF recombinants related to CRF12_BF have been in circulation in Buenos Aires since 1986 and continue to predominate in perinatal transmissions.

Diverse BF recombinants have spread widely since the introduction of HIV-1 into South America.

OBJECTIVE: To describe the genetic diversity of HIV-1 in South America by full genome sequencing and analysis. METHODS: Purified peripheral blood mononuclear cell DNA from HIV-infected individuals in Argentina, Uruguay and Bolivia was used to amplify full HIV-1 genomes. These were sequenced using the ABI 3100 automated sequencer and phylogenetically analysed. RESULTS: Twenty-one HIV-1 strains from three South American countries, 17 of which were pre-screened by envelope heteroduplex mobility assay (HMA), were studied. Ten out of 10 HMA subtype F and four out of seven HMA subtype B strains were actually BF recombinants upon full genome analysis. Two BF recombinants from Argentina and two from Uruguay had the same structure, representing a new circulating recombinant form termed CRF12_BF(ARMA159). Twelve other BF recombinants had structures related to CRF12 but with additional segments of subtype B; each was unique. BF recombinants were temporally and geographically widespread, found as early as 1986-1987 in vertically infected Argentinian children and in Argentina, Uruguay, and Bolivia.

A distinctive clade B HIV type 1 is heterosexually transmitted in Trinidad and Tobago.

HIV-1 transmission worldwide is predominantly associated with heterosexual activity, and non-clade B viruses account for the most spread. The HIV-1 epidemic in Trinidad/Tobago and the Caribbean shares many features with such heterosexual epidemics, including a prominent role for coincident sexually transmitted diseases. This study evaluates the molecular epidemiology of HIV-1 in Trinidad/Tobago during a period when abrupt transition from homosexual to heterosexual transmission occurred in the absence of injecting drug use, concomitant with a rapid rise in HIV-1 prevalence in the heterosexual population. Of 31 viral isolates studied during 1987-1995, all cluster with subtype B reference strains. In the analysis of full env genes from 22 early seroconverters, the Trinidad isolates constitute a significant subcluster within the B subtype. The Trinidad V3 consensus sequence differs by a single amino acid from the prototype B V3 consensus and demonstrates stability over the decade of this study. In the majority of isolates, the V3 loop of env contains a signature threonine deletion that marks the lineage of the Trinidad HIV-1 clade B epidemic from pre-1984. No phenotypic features, including syncitium induction, neutralization profiles, and chemokine receptor usage, distinguish this virus population from other subtype B viruses. Thus, although the subtype B HIV-1 viruses being transmitted in Trinidad are genetically distinguishable from other subtype B viruses, this is probably the result of a strong founder effect in a geographically circumscribed population rather than genetic selection for heterosexual transmission. These results demonstrate that canonical clade B HIV-1 can generate a typical heterosexual epidemic.

Emerging genetic diversity of HIV-1 in South America.

OBJECTIVE: Genotype determination and risk group analysis of HIV-1 infected individuals in selected regions of South America. DESIGN: Cross-sectional convenience sampling of HIV-1-positive individuals in Peru, Ecuador, Uruguay and Paraguay from March, 1994 through September, 1998. METHODS: HIV-1-positive subjects were identified through the national AIDS surveillance program in each country. A standardized questionnaire was used to obtain demographic, clinical and risk factor data on each study subject. Viral DNA was extracted from participants' peripheral blood mononuclear cells either directly or after co-cultivation. A nested PCR was used to obtain selected fragments of the envelope genes for genotyping by the heteroduplex mobility assay (HMA). A 600 bp sequence encompassing the V3 loop was sequenced from a selection of 23 of these samples for phylogenetic analysis and confirmation of HMA genotype. RESULTS: Among the 257 successfully genotyped HIV-1-positive samples, genotype B was found in 98.3% (228/232) of those obtained from subjects in Peru, Ecuador, and Paraguay. In contrast, 56% (14/25) of the samples from Uruguay were genotype F, and the remainder were genotype B. Genotype F was detected for the first time in Peru (2/224) and Paraguay (1/4), and genotype A for the first time in Peru (1/224). Phylogenetic analysis confirmed the genotype identified by HMA in the 23 samples sequenced. There was no detectable genetic clustering of HIV-1 within the different high-risk groups or geographic locations. CONCLUSIONS: These findings verify and extend the presence of several different HIV-1 genotypes in South America.

Virtually full-length subtype F and F/D recombinant HIV-1 from Africa and South America.

For reliable classification of HIV-1 strains appropriate reference sequences are needed. The HIV-1 genetic subtype F has a wide geographic spread, causing significant epidemics in South America, Africa, and some regions of Europe. Previously only two full-length sequences of each of the HIV-1 subtype F subclusters F1 and F2 have been described. To extend the knowledge of subtype F variation on a complete genome level, three new virtually full-length F1 sequences were cloned and sequenced, two from Africa and one from South America. Comparison of the new and previously described sequences showed that monophyletic clustering of the subcluster F1 of subtype F is consistent and highly supported in all genome regions. Two additional full-length strains were shown to be mosaics of subtypes F and D. These epidemiologically unrelated F/D sequences showed similar chimeric structure, suggesting that they may represent a previously undescribed circulating recombinant form (CRF). This was supported by partial sequences from three additional unlinked F/D recombinants. Genetic distances in the phylogenetic trees suggest that the recombination event leading to the putative CRF occurred relatively long ago, close to the divergence of the F1 and F2 subclusters. Furthermore, all five F/D recombinants are linked to the Democratic Republic of Congo, suggesting that the original recombination event took place in central Africa.

Multiple introductions of HIV-1 subtype E into the western hemisphere.

There are nine recognised genetic subtypes of HIV-1, and the epidemic in Southeast Asia is largely due to subtype E. We have investigated HIV-1 viral subtypes in 11 Uruguayan military personnel, six with infection acquired during a United Nations deployment to Cambodia and five with infection acquired in South America. We found subtype E in five of the six infections acquired in Southeast Asia, and subtype B in all five of the domestically acquired cases. These findings document multiple introductions of HIV-1 subtype E into the western hemisphere and mean that the genetic diversity of the global HIV-1 pandemic must be considered in strategies for epidemic control.

PIP: The genetic analysis of viruses from 11 HIV-infected Uruguayan military personnel, 6 of whom are thought to have acquired their infection while deployed as part of the UN Transitional Authority in Cambodia, is reported. They were screened for antibodies to HIV-1 before deployment, on return, and one month after return. 10 (.8%) of 1300 individuals acquired HIV-1 infection during overseas deployment. 6 of these 10 and 5 military personnel with domestically acquired infections volunteered for this study. The five had been diagnosed when tested as part of sentinel screening or at blood donation. Medical histories indicated that for all but 1 of the 11 subjects (who did not deploy to Cambodia), transmission most likely occurred through heterosexual exposures. The virus was successfully isolated by coculture in six individuals (four nondeployed, two deployed), and the genetic analyses were carried out on DNA prepared from cocultured peripheral blood mononuclear cells (PBMC) from these subjects. Genetic analyses of viruses from the other five subjects were done on DNA from primary PBMC. Phylogenetic analysis of the DNA sequences from the gp 120 fragment obtained from the five subjects who did not deploy and had not traveled outside South America revealed that all clustered within the B subtype of HIV-1. Of the six subjects who were infected while deployed to Cambodia, five harbored HIV-1 subtype E, while the sixth isolate (UR5) was subtype B. Cross-sectional surveys in several populations in Uruguay have revealed a low overall seroprevalence of HIV-1, with the highest prevalence (1.26% of 868 patients tested) found in a population from a sexually transmitted diseases clinic in Montevideo. The biological consequences of the introduction of subtype E HIV-1 into the western hemisphere are not known, but data from Thailand suggest that subtype E may be associated with a higher risk of heterosexual transmission than B.